1. Chapter 21 - Standard Template Library (STL)
Outline
Introduction to the Standard Template Library (STL)
Introduction to Containers
Introduction to Iterators
Introduction to Algorithms
Sequence Containers
vector Sequence Container
list Sequence Container
deque Sequence Container
Associative Containers
multiset Associative Container
set Associative Container
multimap Associative Container
map Associative Container
Container Adapters
stack Adapter
queue Adapter
priority_queue Adapter

2. Chapter 21 - Standard Template Library (STL)
Algorithms
fill, fill_n, generate and generate_n
equal, mismatch and lexicographical_compare
remove, remove_if, remove_copy and remove_copy_if
replace, replace_if, replace_copy and replace_copy_if
Mathematical Algorithms
Basic Searching and Sorting Algorithms
swap, iter_swap and swap_ranges
copy_backward, merge, unique and reverse
inplace_merge, unique_copy and reverse_copy
Set Operations
lower_bound, upper_bound and equal_range
Heapsort
min and max
Algorithms Not Covered in This Chapter
Class bitset
Function Objects

3. 21.1 Introduction to the Standard Template Library (STL)
Powerful, template-based components
Containers: template data structures
Iterators: like pointers, access elements of containers
Algorithms: data manipulation, searching, sorting, etc.
Object- oriented programming: reuse, reuse, reuse
Only an introduction to STL, a huge class library

4. 21.1.1 Introduction to Containers
Three types of containers
Sequence containers
Linear data structures (vectors, linked lists)
First-class container
Associative containers
Non-linear, can find elements quickly
Key/value pairs
Container adapters
Near containers
Similar to containers, with reduced functionality
Containers have some common functions

5. STL Container Classes (Fig. 21.1)
Sequence containers
vector
deque
list
Associative containers
set
multiset
map
multimap
Container adapters
stack
queue
priority_queue

6. Common STL Member Functions (Fig. 21.2)
Member functions for all containers
Default constructor, copy constructor, destructor
empty
max_size, size
= < <= > >= == !=
swap
Functions for first-class containers
begin, end
rbegin, rend
erase, clear

7. Common STL typedefs (Fig. 21.4)
typedefs for first-class containers
value_type
reference
const_reference
pointer
iterator
const_iterator
reverse_iterator
const_reverse_iterator
difference_type
size_type

8. 21.1.2 Introduction to Iterators
Iterators similar to pointers
Point to first element in a container
Iterator operators same for all containers
* dereferences
++ points to next element
begin() returns iterator to first element
end() returns iterator to last element
Use iterators with sequences (ranges)
Containers
Input sequences: istream_iterator
Output sequences: ostream_iterator

9. 21.1.2 Introduction to Iterators
Usage
std::istream_iterator< int > inputInt( cin )
Can read input from cin
*inputInt
Dereference to read first int from cin
++inputInt
Go to next int in stream
std::ostream_iterator< int > outputInt(cout)
Can output ints to cout
*outputInt = 7
Outputs 7 to cout
++outputInt
Advances iterator so we can output next int

10. Access and assign the iterator like a pointer.
// Fig. 21.5: fig21_05.cpp
// Demonstrating input and output with iterators.
#include <iostream> 4
using std::cout;
using std::cin;
using std::endl; 8
#include <iterator> // ostream_iterator and istream_iterator 10
11 int main()
12 {
cout << "Enter two integers: "; 14
// create istream_iterator for reading int values from cin
std::istream_iterator< int > inputInt( cin ); 17
int number1 = *inputInt; // read int from standard input
inputInt; // move iterator to next input value
int number2 = *inputInt; // read int from standard input 21
fig21_05.cpp (1 of 2)
Note creation of istream_iterator. For compilation reasons, we use std:: rather than a using statement.
Access and assign the iterator like a pointer.

11. fig21_05.cpp (2 of 2) fig21_05.cpp output (1 of 1)
// create ostream_iterator for writing int values to cout
std::ostream_iterator< int > outputInt( cout ); 24
cout << "The sum is: ";
*outputInt = number1 + number2; // output result to cout
cout << endl; 28
return 0; 30
31 } // end main
fig21_05.cpp (2 of 2) fig21_05.cpp output (1 of 1)
Create an ostream_iterator is similar. Assigning to this iterator outputs to cout.
Enter two integers: 12 25
The sum is: 37

12. Iterator Categories (Fig. 21.6)
Input
Read elements from container, can only move forward
Output
Write elements to container, only forward
Forward
Combines input and output, retains position
Multi-pass (can pass through sequence twice)
Bidirectional
Like forward, but can move backwards as well
Random access
Like bidirectional, but can also jump to any element

13. Iterator Types Supported (Fig. 21.8)
Sequence containers
vector: random access
deque: random access
list: bidirectional
Associative containers (all bidirectional)
set
multiset
Map
multimap
Container adapters (no iterators supported)
stack
queue
priority_queue

14. Iterator Operations (Fig. 21.10)
All
++p, p++
Input iterators *p
p = p1
p == p1, p != p1
Output iterators
Forward iterators
Have functionality of input and output iterators

15. Iterator Operations (Fig. 21.10)
Bidirectional
--p, p--
Random access
p + i, p += i
p - i, p -= i
p[i]
p < p1, p <= p1
p > p1, p >= p1

16. 21.1.3 Introduction to Algorithms
STL has algorithms used generically across containers
Operate on elements indirectly via iterators
Often operate on sequences of elements
Defined by pairs of iterators
First and last element
Algorithms often return iterators
find()
Returns iterator to element, or end() if not found
Premade algorithms save programmers time and effort

17. Three sequence containers
vector - based on arrays
deque - based on arrays
list - robust linked list

18. 21.2.1 vector Sequence Container
Data structure with contiguous memory locations
Access elements with []
Use when data must be sorted and easily accessible
When memory exhausted
Allocates larger, contiguous area of memory
Copies itself there
Deallocates old memory
Has random access iterators

19. 21.2.1 vector Sequence Container
Declarations
std::vector <type> v;
type: int, float, etc.
Iterators
std::vector<type>::const_iterator iterVar;
const_iterator cannot modify elements
std::vector<type>::reverse_iterator iterVar;
Visits elements in reverse order (end to beginning)
Use rbegin to get starting point
Use rend to get ending point

20. 21.2.1 vector Sequence Container
vector functions
v.push_back(value)
Add element to end (found in all sequence containers).
v.size()
Current size of vector
v.capacity()
How much vector can hold before reallocating memory
Reallocation doubles size
vector<type> v(a, a + SIZE)
Creates vector v with elements from array a up to (not including) a + SIZE

21. 21.2.1 vector Sequence Container
vector functions
v.insert(iterator, value )
Inserts value before location of iterator
v.insert(iterator, array , array + SIZE)
Inserts array elements (up to, but not including array + SIZE) into vector
v.erase( iterator )
Remove element from container
v.erase( iter1, iter2 )
Remove elements starting from iter1 and up to (not including) iter2
v.clear()
Erases entire container

22. 21.2.1 vector Sequence Container
vector functions operations
v.front(), v.back()
Return first and last element
v.[elementNumber] = value;
Assign value to an element
v.at[elementNumber] = value;
As above, with range checking
out_of_bounds exception

23. 21.2.1 vector Sequence Container
ostream_iterator
std::ostream_iterator< type > Name( outputStream, separator );
type: outputs values of a certain type
outputStream: iterator output location
separator: character separating outputs
Example
std::ostream_iterator< int > output( cout, " " );
std::copy( iterator1, iterator2, output );
Copies elements from iterator1 up to (not including) iterator2 to output, an ostream_iterator

24. fig21_14.cpp (1 of 3) Create a vector of ints. Call member functions.
// Fig : fig21_14.cpp
// Demonstrating standard library vector class template.
#include <iostream> 4
using std::cout;
using std::cin;
using std::endl; 8
#include <vector> // vector class-template definition 10
11 // prototype for function template printVector
12 template < class T >
13 void printVector( const std::vector< T > &integers2 ); 14
15 int main()
16 {
const int SIZE = 6;
int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 }; 19
std::vector< int > integers; 21
cout << "The initial size of integers is: "
<< integers.size()
<< "\nThe initial capacity of integers is: "
<< integers.capacity(); 26
fig21_14.cpp (1 of 3)
Create a vector of ints.
Call member functions.

25. Add elements to end of vector using push_back.
// function push_back is in every sequence collection
integers.push_back( 2 );
integers.push_back( 3 );
integers.push_back( 4 ); 31
cout << "\nThe size of integers is: " << integers.size()
<< "\nThe capacity of integers is: "
<< integers.capacity(); 35
cout << "\n\nOutput array using pointer notation: "; 37
for ( int *ptr = array; ptr != array + SIZE; ++ptr )
cout << *ptr << ' '; 40
cout << "\nOutput vector using iterator notation: ";
printVector( integers ); 43
cout << "\nReversed contents of vector integers: "; 45
Add elements to end of vector using push_back.
fig21_14.cpp (2 of 3)

26. Walk through vector backwards using a reverse_iterator.
std::vector< int >::reverse_iterator reverseIterator; 47
for ( reverseIterator = integers.rbegin();
reverseIterator!= integers.rend();
reverseIterator )
cout << *reverseIterator << ' '; 52
cout << endl; 54
return 0; 56
57 } // end main 58
59 // function template for outputting vector elements
60 template < class T >
61 void printVector( const std::vector< T > &integers2 )
62 {
std::vector< T >::const_iterator constIterator; 64
for ( constIterator = integers2.begin();
constIterator != integers2.end();
constIterator++ )
cout << *constIterator << ' '; 69
70 } // end function printVector
Walk through vector backwards using a reverse_iterator.
fig21_14.cpp (3 of 3)
Template function to walk through vector forwards.

27. fig21_14.cpp output (1 of 1) The initial size of v is: 0
The initial capacity of v is: 0
The size of v is: 3
The capacity of v is: 4
Contents of array a using pointer notation:
Contents of vector v using iterator notation: 2 3 4
Reversed contents of vector v: 4 3 2
fig21_14.cpp output (1 of 1)

28. Create vector (initialized using an array) and ostream_iterator.
// Fig : fig21_15.cpp
// Testing Standard Library vector class template
// element-manipulation functions.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <vector> // vector class-template definition
10 #include <algorithm> // copy algorithm 11
12 int main()
13 {
const int SIZE = 6;
int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 }; 16
std::vector< int > integers( array, array + SIZE );
std::ostream_iterator< int > output( cout, " " ); 19
cout << "Vector integers contains: ";
std::copy( integers.begin(), integers.end(), output ); 22
cout << "\nFirst element of integers: " << integers.front()
<< "\nLast element of integers: " << integers.back(); 25
fig21_15.cpp (1 of 3)
Create vector (initialized using an array) and ostream_iterator.
Copy range of iterators to output (ostream_iterator).

29. More vector member functions. fig21_15.cpp (2 of 3)
integers[ 0 ] = 7; // set first element to 7
integers.at( 2 ) = 10; // set element at position 2 to 10 28
// insert 22 as 2nd element
integers.insert( integers.begin() + 1, 22 ); 31
cout << "\n\nContents of vector integers after changes: ";
std::copy( integers.begin(), integers.end(), output ); 34
// access out-of-range element
try {
integers.at( 100 ) = 777; 38
} // end try 40
// catch out_of_range exception
catch ( std::out_of_range outOfRange ) {
cout << "\n\nException: " << outOfRange.what(); 44
} // end catch 46
// erase first element
integers.erase( integers.begin() );
cout << "\n\nVector integers after erasing first element: ";
std::copy( integers.begin(), integers.end(), output ); 51
More vector member functions.
fig21_15.cpp (2 of 3)
at has range checking, and can throw an exception.

30. fig21_15.cpp (3 of 3) 52 // erase remaining elements
integers.erase( integers.begin(), integers.end() );
cout << "\nAfter erasing all elements, vector integers "
<< ( integers.empty() ? "is" : "is not" ) << " empty"; 56
// insert elements from array
integers.insert( integers.begin(), array, array + SIZE );
cout << "\n\nContents of vector integers before clear: ";
std::copy( integers.begin(), integers.end(), output ); 61
// empty integers; clear calls erase to empty a collection
integers.clear();
cout << "\nAfter clear, vector integers "
<< ( integers.empty() ? "is" : "is not" ) << " empty"; 66
cout << endl; 68
return 0; 70
71 } // end main
fig21_15.cpp (3 of 3)

31. fig21_15.cpp output (1 of 1) Vector integers contains: 1 2 3 4 5 6
First element of integers: 1
Last element of integers: 6
Contents of vector integers after changes:
Exception: invalid vector<T> subscript
Vector integers after erasing first element:
After erasing all elements, vector integers is empty
Contents of vector integers before clear:
After clear, vector integers is empty
fig21_15.cpp output (1 of 1)

32. 21.2.2 list Sequence Container
list container
Header <list>
Efficient insertion/deletion anywhere in container
Doubly-linked list (two pointers per node)
Bidirectional iterators
std::list< type > name;

33. 21.2.2 list Sequence Container
list functions for object t
t.sort()
Sorts in ascending order
t.splice(iterator, otherObject );
Inserts values from otherObject before iterator
t.merge( otherObject )
Removes otherObject and inserts it into t, sorted
t.unique()
Removes duplicate elements

34. 21.2.2 list Sequence Container
list functions
t.swap(otherObject);
Exchange contents
t.assign(iterator1, iterator2)
Replaces contents with elements in range of iterators
t.remove(value)
Erases all instances of value

35. Create two list objects.
// Fig : fig21_17.cpp
// Standard library list class template test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <list> // list class-template definition
#include <algorithm> // copy algorithm 10
11 // prototype for function template printList
12 template < class T >
13 void printList( const std::list< T > &listRef ); 14
15 int main()
16 {
const int SIZE = 4;
int array[ SIZE ] = { 2, 6, 4, 8 }; 19
std::list< int > values;
std::list< int > otherValues; 22
// insert items in values
values.push_front( 1 );
values.push_front( 2 );
values.push_back( 4 );
values.push_back( 3 );
fig21_17.cpp (1 of 5)
Create two list objects.

36. Various list member functions.28
cout << "values contains: ";
printList( values ); 31
values.sort(); // sort values 33
cout << "\nvalues after sorting contains: ";
printList( values ); 36
// insert elements of array into otherValues
otherValues.insert( otherValues.begin(),
array, array + SIZE ); 40
cout << "\nAfter insert, otherValues contains: ";
printList( otherValues ); 43
// remove otherValues elements and insert at end of values
values.splice( values.end(), otherValues ); 46
cout << "\nAfter splice, values contains: ";
printList( values ); 49
values.sort(); // sort values 51
cout << "\nAfter sort, values contains: ";
printList( values ); 54
Various list member functions.
fig21_17.cpp (2 of 5)

37. fig21_17.cpp (3 of 5) 55 // insert elements of array into otherValues
otherValues.insert( otherValues.begin(),
array, array + SIZE );
otherValues.sort(); 59
cout << "\nAfter insert, otherValues contains: ";
printList( otherValues ); 62
// remove otherValues elements and insert into values
// in sorted order
values.merge( otherValues ); 66
cout << "\nAfter merge:\n values contains: ";
printList( values );
cout << "\n otherValues contains: ";
printList( otherValues ); 71
values.pop_front(); // remove element from front
values.pop_back(); // remove element from back 74
cout << "\nAfter pop_front and pop_back:"
<< "\n values contains: ";
printList( values ); 78
values.unique(); // remove duplicate elements 80
cout << "\nAfter unique, values contains: ";
printList( values );
fig21_17.cpp (3 of 5)

38. fig21_17.cpp (4 of 5) 83 84 // swap elements of values and otherValues
values.swap( otherValues ); 86
cout << "\nAfter swap:\n values contains: ";
printList( values );
cout << "\n otherValues contains: ";
printList( otherValues ); 91
// replace contents of values with elements of otherValues
values.assign( otherValues.begin(), otherValues.end() ); 94
cout << "\nAfter assign, values contains: ";
printList( values ); 97
// remove otherValues elements and insert into values
// in sorted order
values.merge( otherValues );
101
cout << "\nAfter merge, values contains: ";
printList( values );
104
values.remove( 4 ); // remove all 4s
106
cout << "\nAfter remove( 4 ), values contains: ";
printList( values );
fig21_17.cpp (4 of 5)

39. fig21_17.cpp (5 of 5) 109 110 cout << endl; 111 112 return 0;
113
114 } // end main
115
116 // printList function template definition; uses
117 // ostream_iterator and copy algorithm to output list elements
118 template < class T >
119 void printList( const std::list< T > &listRef )
120 {
if ( listRef.empty() )
cout << "List is empty";
123
else {
std::ostream_iterator< T > output( cout, " " );
std::copy( listRef.begin(), listRef.end(), output );
127
} // end else
129
130 } // end function printList
fig21_17.cpp (5 of 5)

40. fig21_17.cpp output (1 of 1) values contains: 2 1 4 3
values after sorting contains:
After insert, otherValues contains:
After splice, values contains:
After sort, values contains:
After insert, otherValues contains:
After merge:
values contains:
otherValues contains: List is empty
After pop_front and pop_back:
values contains:
After unique, values contains:
After swap:
values contains: List is empty
otherValues contains:
After assign, values contains:
After merge, values contains:
After remove( 4 ), values contains:
fig21_17.cpp output (1 of 1)

41. 21.2.3 deque Sequence Container
deque ("deek"): double-ended queue
Header <deque>
Indexed access using []
Efficient insertion/deletion in front and back
Non-contiguous memory: has "smarter" iterators
Same basic operations as vector
Also has
push_front (insert at front of deque)
pop_front (delete from front)

42. Create a deque, use member functions.
// Fig : fig21_18.cpp
// Standard library class deque test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <deque> // deque class-template definition
#include <algorithm> // copy algorithm 10
11 int main()
12 {
std::deque< double > values;
std::ostream_iterator< double > output( cout, " " ); 15
// insert elements in values
values.push_front( 2.2 );
values.push_front( 3.5 );
values.push_back( 1.1 ); 20
cout << "values contains: "; 22
// use subscript operator to obtain elements of values
for ( int i = 0; i < values.size(); ++i )
cout << values[ i ] << ' '; 26
fig21_18.cpp (1 of 2)
Create a deque, use member functions.

43. fig21_18.cpp (2 of 2) fig21_18.cpp output (1 of 1)
values.pop_front(); // remove first element 28
cout << "\nAfter pop_front, values contains: ";
std::copy( values.begin(), values.end(), output ); 31
// use subscript operator to modify element at location 1
values[ 1 ] = 5.4; 34
cout << "\nAfter values[ 1 ] = 5.4, values contains: ";
std::copy( values.begin(), values.end(), output ); 37
cout << endl; 39
return 0; 41
42 } // end main
fig21_18.cpp (2 of 2) fig21_18.cpp output (1 of 1)
values contains:
After pop_front, values contains:
After values[ 1 ] = 5.4, values contains:

44. 21.3 Associative Containers
Direct access to store/retrieve elements
Uses keys (search keys)
4 types: multiset, set, multimap and map
Keys in sorted order
multiset and multimap allow duplicate keys
multimap and map have keys and associated values
multiset and set only have values

45. 21.3.1 multiset Associative Container
Header <set>
Fast storage, retrieval of keys (no values)
Allows duplicates
Bidirectional iterators
Ordering of elements
Done by comparator function object
Used when creating multiset
For integer multiset
less<int> comparator function object
multiset< int, std::less<int> > myObject;
Elements will be sorted in ascending order

46. 21.3.1 multiset Associative Container
Multiset functions
ms.insert(value)
Inserts value into multiset
ms.count(value)
Returns number of occurrences of value
ms.find(value)
Returns iterator to first instance of value
ms.lower_bound(value)
Returns iterator to first location of value
ms.upper_bound(value)
Returns iterator to location after last occurrence of value

47. 21.3.1 multiset Associative Container
Class pair
Manipulate pairs of values
Pair objects contain first and second
const_iterators
For a pair object q
q = ms.equal_range(value)
Sets first and second to lower_bound and upper_bound for a given value

48. // Fig : fig21_19.cpp
// Testing Standard Library class multiset
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <set> // multiset class-template definition 9
10 // define short name for multiset type used in this program
11 typedef std::multiset< int, std::less< int > > ims; 12
13 #include <algorithm> // copy algorithm 14
15 int main()
16 {
const int SIZE = 10;
int a[ SIZE ] = { 7, 22, 9, 1, 18, 30, 100, 22, 85, 13 }; 19
ims intMultiset; // ims is typedef for "integer multiset"
std::ostream_iterator< int > output( cout, " " ); 22
cout << "There are currently " << intMultiset.count( 15 )
<< " values of 15 in the multiset\n"; 25
fig21_19.cpp (1 of 3)
typedefs help clarify program. This declares an integer multiset that stores values in ascending order.

49. Use member function find.
intMultiset.insert( 15 ); // insert 15 in intMultiset
intMultiset.insert( 15 ); // insert 15 in intMultiset 28
cout << "After inserts, there are "
<< intMultiset.count( 15 )
<< " values of 15 in the multiset\n\n"; 32
// iterator that cannot be used to change element values
ims::const_iterator result; 35
// find 15 in intMultiset; find returns iterator
result = intMultiset.find( 15 ); 38
if ( result != intMultiset.end() ) // if iterator not at end
cout << "Found value 15\n"; // found search value 15 41
// find 20 in intMultiset; find returns iterator
result = intMultiset.find( 20 ); 44
if ( result == intMultiset.end() ) // will be true hence
cout << "Did not find value 20\n"; // did not find 20 47
// insert elements of array a into intMultiset
intMultiset.insert( a, a + SIZE ); 50
cout << "\nAfter insert, intMultiset contains:\n";
std::copy( intMultiset.begin(), intMultiset.end(), output ); 53
fig21_19.cpp (2 of 3)
Use member function find.

50. Use a pair object to get the lower and upper bound for 22.
// determine lower and upper bound of 22 in intMultiset
cout << "\n\nLower bound of 22: "
<< *( intMultiset.lower_bound( 22 ) );
cout << "\nUpper bound of 22: "
<< *( intMultiset.upper_bound( 22 ) ); 59
// p represents pair of const_iterators
std::pair< ims::const_iterator, ims::const_iterator > p; 62
// use equal_range to determine lower and upper bound
// of 22 in intMultiset
p = intMultiset.equal_range( 22 ); 66
cout << "\n\nequal_range of 22:"
<< "\n Lower bound: " << *( p.first )
<< "\n Upper bound: " << *( p.second ); 70
cout << endl; 72
return 0; 74
75 } // end main
fig21_19.cpp (3 of 3)
Use a pair object to get the lower and upper bound for 22.

51. There are currently 0 values of 15 in the multiset
After inserts, there are 2 values of 15 in the multiset
Found value 15
Did not find value 20
After insert, intMultiset contains:
Lower bound of 22: 22
Upper bound of 22: 30
equal_range of 22:
Lower bound: 22
Upper bound: 30
fig21_19.cpp output (1 of 1)

52. 21.3.2 set Associative Container
Header <set>
Implementation identical to multiset
Unique keys
Duplicates ignored and not inserted
Supports bidirectional iterators (but not random access)
std::set< type, std::less<type> > name;

53. Create set. Syntax similar to multiset.
// Fig : fig21_20.cpp
// Standard library class set test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <set> 9
10 // define short name for set type used in this program
11 typedef std::set< double, std::less< double > > double_set; 12
13 #include <algorithm> 14
15 int main()
16 {
const int SIZE = 5;
double a[ SIZE ] = { 2.1, 4.2, 9.5, 2.1, 3.7 }; 19
double_set doubleSet( a, a + SIZE );
std::ostream_iterator< double > output( cout, " " ); 22
cout << "doubleSet contains: ";
std::copy( doubleSet.begin(), doubleSet.end(), output ); 25
fig21_20.cpp (1 of 3)
Create set. Syntax similar to multiset.

54. 26 // p represents pair containing const_iterator and bool
std::pair< double_set::const_iterator, bool > p; 28
// insert 13.8 in doubleSet; insert returns pair in which
// p.first represents location of 13.8 in doubleSet and
// p.second represents whether 13.8 was inserted
p = doubleSet.insert( 13.8 ); // value not in set 33
cout << "\n\n" << *( p.first )
<< ( p.second ? " was" : " was not" ) << " inserted"; 36
cout << "\ndoubleSet contains: ";
std::copy( doubleSet.begin(), doubleSet.end(), output ); 39
// insert 9.5 in doubleSet
p = doubleSet.insert( 9.5 ); // value already in set 42
cout << "\n\n" << *( p.first )
<< ( p.second ? " was" : " was not" ) << " inserted"; 45
fig21_20.cpp (2 of 3)
pair object has a bool value representing whether or not the item was inserted.

55. fig21_20.cpp (3 of 3) fig21_20.cpp output (1 of 1)
cout << "\ndoubleSet contains: ";
std::copy( doubleSet.begin(), doubleSet.end(), output ); 48
cout << endl; 50
return 0; 52
53 } // end main
fig21_20.cpp (3 of 3) fig21_20.cpp output (1 of 1)
doubleSet contains:
13.8 was inserted
doubleSet contains:
9.5 was not inserted

56. 21.3.3 multimap Associative Container
Header <map>
Fast storage and retrieval of keys and associated values
Has key/value pairs
Duplicate keys allowed (multiple values for a single key)
One-to-many relationship
I.e., one student can take many courses
Insert pair objects (with a key and value)
Bidirectional iterators

57. 21.3.3 multimap Associative Container
Example
std::multimap< int, double, std::less< int > > mmapObject;
Key type int
Value type double
Sorted in ascending order
Use typedef to simplify code
typedef std::multimap<int, double, std::less<int>> mmid;
mmid mmapObject;
mmapObject.insert( mmid::value_type( 1, 3.4 ) );
Inserts key 1 with value 3.4
mmid::value_type creates a pair object

58. Definition for a multimap that maps integer keys to double values.
// Fig : fig21_21.cpp
// Standard library class multimap test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <map> // map class-template definition 9
10 // define short name for multimap type used in this program
11 typedef std::multimap< int, double, std::less< int > > mmid; 12
13 int main()
14 {
mmid pairs; 16
cout << "There are currently " << pairs.count( 15 )
<< " pairs with key 15 in the multimap\n"; 19
// insert two value_type objects in pairs
pairs.insert( mmid::value_type( 15, 2.7 ) );
pairs.insert( mmid::value_type( 15, 99.3 ) ); 23
cout << "After inserts, there are "
<< pairs.count( 15 )
<< " pairs with key 15\n\n";
fig21_21.cpp (1 of 2)
Definition for a multimap that maps integer keys to double values.
Create multimap and insert key-value pairs.

59. Use iterator to print entire multimap.27
// insert five value_type objects in pairs
pairs.insert( mmid::value_type( 30, ) );
pairs.insert( mmid::value_type( 10, ) );
pairs.insert( mmid::value_type( 25, ) );
pairs.insert( mmid::value_type( 20, ) );
pairs.insert( mmid::value_type( 5, ) ); 34
cout << "Multimap pairs contains:\nKey\tValue\n"; 36
// use const_iterator to walk through elements of pairs
for ( mmid::const_iterator iter = pairs.begin();
iter != pairs.end(); ++iter )
cout << iter->first << '\t'
<< iter->second << '\n'; 42
cout << endl; 44
return 0; 46
47 } // end main
fig21_21.cpp (2 of 2)
Use iterator to print entire multimap.

60. There are currently 0 pairs with key 15 in the multimap
After inserts, there are 2 pairs with key 15
Multimap pairs contains:
Key Value
fig21_21.cpp output (1 of 1)

61. 21.3.4 map Associative Container
Header <map>
Like multimap, but only unique key/value pairs
One-to-one mapping (duplicates ignored)
Use [] to access values
Example: for map object m
m[30] = ;
Sets the value of key 30 to
If subscript not in map, creates new key/value pair
Type declaration
std::map< int, double, std::less< int > >;

62. Again, use typedefs to simplify declaration.
// Fig : fig21_22.cpp
// Standard library class map test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <map> // map class-template definition 9
10 // define short name for map type used in this program
11 typedef std::map< int, double, std::less< int > > mid; 12
13 int main()
14 {
mid pairs; 16
// insert eight value_type objects in pairs
pairs.insert( mid::value_type( 15, 2.7 ) );
pairs.insert( mid::value_type( 30, ) );
pairs.insert( mid::value_type( 5, ) );
pairs.insert( mid::value_type( 10, ) );
pairs.insert( mid::value_type( 25, ) );
pairs.insert( mid::value_type( 5, ) ); // dupe ignored
pairs.insert( mid::value_type( 20, ) );
pairs.insert( mid::value_type( 15, 99.3 ) ); // dupe ignored 26
fig21_22.cpp (1 of 2)
Again, use typedefs to simplify declaration.
Duplicate keys ignored.

63. Can use subscript operator to add or change key-value pairs.
cout << "pairs contains:\nKey\tValue\n"; 28
// use const_iterator to walk through elements of pairs
for ( mid::const_iterator iter = pairs.begin();
iter != pairs.end(); ++iter )
cout << iter->first << '\t'
<< iter->second << '\n'; 34
// use subscript operator to change value for key 25
pairs[ 25 ] = ; 37
// use subscript operator insert value for key 40
pairs[ 40 ] = ; 40
cout << "\nAfter subscript operations, pairs contains:"
<< "\nKey\tValue\n"; 43
for ( mid::const_iterator iter2 = pairs.begin();
iter2 != pairs.end(); ++iter2 )
cout << iter2->first << '\t'
<< iter2->second << '\n'; 48
cout << endl; 50
return 0; 52
53 } // end main
fig21_22.cpp (2 of 2)
Can use subscript operator to add or change key-value pairs.

64. fig21_22.cpp output (1 of 1) pairs contains: Key Value 5 1010.1
After subscript operations, pairs contains:
fig21_22.cpp output (1 of 1)

65. 21.4 Container Adapters Container adapters
stack, queue and priority_queue
Not first class containers
Do not support iterators
Do not provide actual data structure
Programmer can select implementation
Member functions push and pop

66. 21.4.1 stack Adapter stack Header <stack>
Insertions and deletions at one end
Last-in, first-out (LIFO) data structure
Can use vector, list, or deque (default)
Declarations
stack<type, vector<type> > myStack;
stack<type, list<type> > myOtherStack;
stack<type> anotherStack; // default deque
vector, list
Implementation of stack (default deque)
Does not change behavior, just performance (deque and vector fastest)

67. Create stacks with various implementations.
// Fig : fig21_23.cpp
// Standard library adapter stack test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <stack> // stack adapter definition
#include <vector> // vector class-template definition
10 #include <list> // list class-template definition 11
12 // popElements function-template prototype
13 template< class T >
14 void popElements( T &stackRef ); 15
16 int main()
17 {
// stack with default underlying deque
std::stack< int > intDequeStack; 20
// stack with underlying vector
std::stack< int, std::vector< int > > intVectorStack; 23
// stack with underlying list
std::stack< int, std::list< int > > intListStack; 26
fig21_23.cpp (1 of 3)
Create stacks with various implementations.

68. Use member function push. fig21_23.cpp (2 of 3)
// push the values 0-9 onto each stack
for ( int i = 0; i < 10; ++i ) {
intDequeStack.push( i );
intVectorStack.push( i );
intListStack.push( i ); 32
} // end for 34
// display and remove elements from each stack
cout << "Popping from intDequeStack: ";
popElements( intDequeStack );
cout << "\nPopping from intVectorStack: ";
popElements( intVectorStack );
cout << "\nPopping from intListStack: ";
popElements( intListStack ); 42
cout << endl; 44
return 0; 46
47 } // end main 48
Use member function push.
fig21_23.cpp (2 of 3)

69. fig21_23.cpp (3 of 3) fig21_23.cpp output (1 of 1)
49 // pop elements from stack object to which stackRef refers
50 template< class T >
51 void popElements( T &stackRef )
52 {
while ( !stackRef.empty() ) {
cout << stackRef.top() << ' '; // view top element
stackRef.pop(); // remove top element 56
} // end while 58
59 } // end function popElements
fig21_23.cpp (3 of 3) fig21_23.cpp output (1 of 1)
Popping from intDequeStack:
Popping from intVectorStack:
Popping from intListStack:

70. 21.4.2 queue Adapter queue Functions Header <queue>
Insertions at back, deletions at front
First-in-first-out (FIFO) data structure
Implemented with list or deque (default)
std::queue<double> values;
Functions
push( element )
Same as push_back, add to end
pop( element )
Implemented with pop_front, remove from front
empty()
size()

71. Create queue, add values using push.
// Fig : fig21_24.cpp
// Standard library adapter queue test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <queue> // queue adapter definition 9
10 int main()
11 {
std::queue< double > values; 13
// push elements onto queue values
values.push( 3.2 );
values.push( 9.8 );
values.push( 5.4 ); 18
cout << "Popping from values: "; 20
while ( !values.empty() ) {
cout << values.front() << ' '; // view front element
values.pop(); // remove element 24
} // end while 26
fig21_24.cpp (1 of 2)
Create queue, add values using push.

72. fig21_24.cpp (2 of 2) fig21_24.cpp output (1 of 1)
cout << endl; 28
return 0; 30
31 } // end main
fig21_24.cpp (2 of 2) fig21_24.cpp output (1 of 1)
Popping from values:

73. 21.4.3 priority_queue Adapter
Header <queue>
Insertions happen in sorted order, deletions from front
Implemented with vector (default) or deque
Highest priority element always removed first
Heapsort algorithm puts largest elements at front
less<T> default, programmer can specify other comparator
Functions
push(value), pop(value)
top()
View top element
size()
empty()

74. fig21_25.cpp (1 of 2) Create priority queue.
// Fig : fig21_25.cpp
// Standard library adapter priority_queue test program.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <queue> // priority_queue adapter definition 9
10 int main()
11 {
std::priority_queue< double > priorities; 13
// push elements onto priorities
priorities.push( 3.2 );
priorities.push( 9.8 );
priorities.push( 5.4 ); 18
cout << "Popping from priorities: "; 20
while ( !priorities.empty() ) {
cout << priorities.top() << ' '; // view top element
priorities.pop(); // remove top element 24
} // end while 26
fig21_25.cpp (1 of 2)
Create priority queue.
Insert items using push. When using pop, highest priority (largest) items removed first.

75. fig21_25.cpp (2 of 2) fig21_25.cpp output (1 of 1)
cout << endl; 28
return 0; 30
31 } // end main
fig21_25.cpp (2 of 2) fig21_25.cpp output (1 of 1)
Popping from priorities:

76. STL separates containers and algorithms
Before STL
Class libraries incompatible among vendors
Algorithms built into container classes
STL separates containers and algorithms
Easier to add new algorithms
More efficient, avoids virtual function calls
<algorithm>

77. 21.5.1 fill, fill_n, generate and generate_n
Functions to change containers
fill(iterator1, iterator2, value);
Sets range of elements to value
fill_n(iterator1, n, value);
Sets n elements to value, starting at iterator1
generate(iterator1, iterator2, function);
Like fill, but calls function to set each value
generate(iterator1, quantity, function)
Like fill_n, ""

78. Create vector of chars, to be used with various functions.
// Fig : fig21_26.cpp
// Standard library algorithms fill, fill_n, generate
// and generate_n.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition 11
12 char nextLetter(); // prototype 13
14 int main()
15 {
std::vector< char > chars( 10 );
std::ostream_iterator< char > output( cout, " " ); 18
// fill chars with 5s
std::fill( chars.begin(), chars.end(), '5' ); 21
cout << "Vector chars after filling with 5s:\n";
std::copy( chars.begin(), chars.end(), output ); 24
fig21_26.cpp (1 of 3)
Create vector of chars, to be used with various functions.
Function fill.

79. Functions generate and generate_n use function nextLetter.
// fill first five elements of chars with As
std::fill_n( chars.begin(), 5, 'A' ); 27
cout << "\n\nVector chars after filling five elements"
<< " with As:\n";
std::copy( chars.begin(), chars.end(), output ); 31
// generate values for all elements of chars with nextLetter
std::generate( chars.begin(), chars.end(), nextLetter ); 34
cout << "\n\nVector chars after generating letters A-J:\n";
std::copy( chars.begin(), chars.end(), output ); 37
// generate values for first five elements of chars
// with nextLetter
std::generate_n( chars.begin(), 5, nextLetter ); 41
cout << "\n\nVector chars after generating K-O for the"
<< " first five elements:\n";
std::copy( chars.begin(), chars.end(), output ); 45
cout << endl; 47
return 0; 49
50 } // end main
fig21_26.cpp (2 of 3)
Functions generate and generate_n use function nextLetter.

80. fig21_26.cpp (3 of 3) fig21_26.cpp output (1 of 1)51
52 // returns next letter in the alphabet (starts with A)
53 char nextLetter()
54 {
static char letter = 'A';
return letter++; 57
58 } // end function nextLetter
fig21_26.cpp (3 of 3) fig21_26.cpp output (1 of 1)
Vector chars after filling with 5s:
Vector chars after filling five elements with As:
A A A A A
Vector chars after generating letters A-J:
A B C D E F G H I J
Vector chars after generating K-O for the first five elements:
K L M N O F G H I J

81. 21.5.2 equal, mismatch and lexicographical_compare
Functions to compare sequences of values
equal
Returns true if sequences are equal (uses ==)
Can return false if of unequal length
equal(iterator1, iterator2, iterator3);
Compares sequence from iterator1 to iterator2 with sequence beginning at iterator3
mismatch
Arguments same as equal
Returns a pair object with iterators pointing to mismatch
If no mismatch, pair iterators equal to last item
pair < iterator, iterator > myPairObject;
myPairObject = mismatch( iter1, iter2, iter3);

82. 21.5.2 equal, mismatch and lexicographical_compare
Functions to compare sequences of values
lexicographical_compare
Compare contents of two character arrays
Returns true if element in first sequence smaller than corresponding element in second
bool result = lexicographical_compare(iter1, iter2, iter3);

83. fig21_27.cpp (1 of 3) 1 // Fig. 21.27: fig21_27.cpp
// Standard library functions equal,
// mismatch and lexicographical_compare.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition 11
12 int main()
13 {
const int SIZE = 10;
int a1[ SIZE ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int a2[ SIZE ] = { 1, 2, 3, 4, 1000, 6, 7, 8, 9, 10 }; 17
std::vector< int > v1( a1, a1 + SIZE );
std::vector< int > v2( a1, a1 + SIZE );
std::vector< int > v3( a2, a2 + SIZE ); 21
std::ostream_iterator< int > output( cout, " " ); 23
fig21_27.cpp (1 of 3)

84. Use function equal. Compares all of v1 with v2.
cout << "Vector v1 contains: ";
std::copy( v1.begin(), v1.end(), output );
cout << "\nVector v2 contains: ";
std::copy( v2.begin(), v2.end(), output );
cout << "\nVector v3 contains: ";
std::copy( v3.begin(), v3.end(), output ); 30
// compare vectors v1 and v2 for equality
bool result =
std::equal( v1.begin(), v1.end(), v2.begin() ); 34
cout << "\n\nVector v1 " << ( result ? "is" : "is not" )
<< " equal to vector v2.\n"; 37
// compare vectors v1 and v3 for equality
result = std::equal( v1.begin(), v1.end(), v3.begin() );
cout << "Vector v1 " << ( result ? "is" : "is not" )
<< " equal to vector v3.\n"; 42
// location represents pair of vector iterators
std::pair< std::vector< int >::iterator,
std::vector< int >::iterator > location; 46
// check for mismatch between v1 and v3
location =
std::mismatch( v1.begin(), v1.end(), v3.begin() ); 50
fig21_27.cpp (2 of 3)
Use function equal. Compares all of v1 with v2.
Note use of function mismatch.

85. Use lexicographical_compare.
cout << "\nThere is a mismatch between v1 and v3 at "
<< "location " << ( location.first - v1.begin() )
<< "\nwhere v1 contains " << *location.first
<< " and v3 contains " << *location.second
<< "\n\n"; 56
char c1[ SIZE ] = "HELLO";
char c2[ SIZE ] = "BYE BYE"; 59
// perform lexicographical comparison of c1 and c2
result = std::lexicographical_compare(
c1, c1 + SIZE, c2, c2 + SIZE ); 63
cout << c1
<< ( result ? " is less than " :
" is greater than or equal to " )
<< c2 << endl; 68
return 0; 70
71 } // end main
fig21_27.cpp (3 of 3)
Use lexicographical_compare.

86. fig21_27.cpp output (1 of 1) Vector v1 contains: 1 2 3 4 5 6 7 8 9 10
Vector v1 is equal to vector v2.
Vector v1 is not equal to vector v3.
There is a mismatch between v1 and v3 at location 4
where v1 contains 5 and v3 contains 1000
HELLO is greater than or equal to BYE BYE
fig21_27.cpp output (1 of 1)

87. 21.5.3 remove, remove_if, remove_copy and remove_copy_if
remove( iter1, iter2, value);
Removes all instances of value in range (iter1-iter2)
Moves instances of value towards end
Does not change size of container or delete elements
Returns iterator to "new" end of container
Elements after new iterator are undefined (0)
remove_copy
Copies one vector to another while removing an element
remove_copy(iter1, iter2, iter3, value);
Copies elements not equal to value into iter3 (output iterator)
Uses range iter1-iter2

88. 21.5.3 remove, remove_if, remove_copy and remove_copy_if
Like remove
Returns iterator to last element
Removes elements that return true for specified function
remove_if(iter1,iter2, function);
Elements passed to function, which returns a bool
remove_copy_if
Like remove_copy and remove_if
Copies range of elements to iter3, except those for which function returns true
remove_copy_if(iter1, iter2, iter3, function);

89. fig21_28.cpp (1 of 4) 1 // Fig. 21.28: fig21_28.cpp
// Standard library functions remove, remove_if,
// remove_copy and remove_copy_if.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition 11
12 bool greater9( int ); // prototype 13
14 int main()
15 {
const int SIZE = 10;
int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; 18
std::ostream_iterator< int > output( cout, " " ); 20
std::vector< int > v( a, a + SIZE );
std::vector< int >::iterator newLastElement; 23
cout << "Vector v before removing all 10s:\n ";
std::copy( v.begin(), v.end(), output ); 26
fig21_28.cpp (1 of 4)

90. Use remove_copy to create a duplicate of v, with all the 10's removed.
// remove 10 from v
newLastElement = std::remove( v.begin(), v.end(), 10 ); 29
cout << "\nVector v after removing all 10s:\n ";
std::copy( v.begin(), newLastElement, output ); 32
std::vector< int > v2( a, a + SIZE );
std::vector< int > c( SIZE, 0 ); 35
cout << "\n\nVector v2 before removing all 10s "
<< "and copying:\n ";
std::copy( v2.begin(), v2.end(), output ); 39
// copy from v2 to c, removing 10s in the process
std::remove_copy( v2.begin(), v2.end(), c.begin(), 10 ); 42
cout << "\nVector c after removing all 10s from v2:\n ";
std::copy( c.begin(), c.end(), output ); 45
std::vector< int > v3( a, a + SIZE ); 47
cout << "\n\nVector v3 before removing all elements"
<< "\ngreater than 9:\n ";
std::copy( v3.begin(), v3.end(), output ); 51
Remove all 10's from v. Returns an iterator pointing to the new last element.
fig21_28.cpp (2 of 4)
Use remove_copy to create a duplicate of v, with all the 10's removed.

91. Use function greater9 to determine whether to remove the element.
// remove elements greater than 9 from v3
newLastElement =
std::remove_if( v3.begin(), v3.end(), greater9 ); 55
cout << "\nVector v3 after removing all elements"
<< "\ngreater than 9:\n ";
std::copy( v3.begin(), newLastElement, output ); 59
std::vector< int > v4( a, a + SIZE );
std::vector< int > c2( SIZE, 0 ); 62
cout << "\n\nVector v4 before removing all elements"
<< "\ngreater than 9 and copying:\n ";
std::copy( v4.begin(), v4.end(), output ); 66
// copy elements from v4 to c2, removing elements greater
// than 9 in the process
std::remove_copy_if(
v4.begin(), v4.end(), c2.begin(), greater9 ); 71
cout << "\nVector c2 after removing all elements"
<< "\ngreater than 9 from v4:\n ";
std::copy( c2.begin(), c2.end(), output ); 75
Use function greater9 to determine whether to remove the element.
fig21_28.cpp (3 of 4)
Note use of remove_copy_if.

92. fig21_28.cpp (4 of 4) 76 cout << endl; 77 78 return 0; 79
80 } // end main 81
82 // determine whether argument is greater than 9
83 bool greater9( int x )
84 {
return x > 9; 86
87 } // end greater9
fig21_28.cpp (4 of 4)

93. fig21_28.cpp output (1 of 1) Vector v before removing all 10s:
Vector v after removing all 10s:
Vector v2 before removing all 10s and copying:
Vector c after removing all 10s from v2:
Vector v3 before removing all elements
greater than 9:
Vector v3 after removing all elements
Vector v4 before removing all elements
greater than 9 and copying:
Vector c2 after removing all elements
greater than 9 from v4:
fig21_28.cpp output (1 of 1)

94. 21.5.4 replace, replace_if, replace_copy and replace_copy_if
Functions
replace( iter1, iter2, value, newvalue );
Like remove, except replaces value with newvalue
replace_if( iter1, iter2, function, newvalue );
Replaces value if function returns true
replace_copy(iter1, iter2, iter3, value, newvalue);
Replaces and copies elements to iter3
Does not affect originals
replace_copy_if( iter1, iter2, iter3, function, newvalue );
Replaces and copies elements to iter3 if function returns true

95. fig21_29.cpp (1 of 4) 1 // Fig. 21.29: fig21_29.cpp
// Standard library functions replace, replace_if,
// replace_copy and replace_copy_if.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm>
10 #include <vector> 11
12 bool greater9( int ); 13
14 int main()
15 {
const int SIZE = 10;
int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; 18
std::ostream_iterator< int > output( cout, " " ); 20
std::vector< int > v1( a, a + SIZE );
cout << "Vector v1 before replacing all 10s:\n ";
std::copy( v1.begin(), v1.end(), output ); 24
fig21_29.cpp (1 of 4)

96. Use functions replace, replace_copy.
// replace 10s in v1 with 100
std::replace( v1.begin(), v1.end(), 10, 100 ); 27
cout << "\nVector v1 after replacing 10s with 100s:\n ";
std::copy( v1.begin(), v1.end(), output ); 30
std::vector< int > v2( a, a + SIZE );
std::vector< int > c1( SIZE ); 33
cout << "\n\nVector v2 before replacing all 10s "
<< "and copying:\n ";
std::copy( v2.begin(), v2.end(), output ); 37
// copy from v2 to c1, replacing 10s with 100s
std::replace_copy(
v2.begin(), v2.end(), c1.begin(), 10, 100 ); 41
cout << "\nVector c1 after replacing all 10s in v2:\n ";
std::copy( c1.begin(), c1.end(), output ); 44
std::vector< int > v3( a, a + SIZE ); 46
cout << "\n\nVector v3 before replacing values greater"
<< " than 9:\n ";
std::copy( v3.begin(), v3.end(), output ); 50
Use functions replace, replace_copy.
fig21_29.cpp (2 of 4)

97. 51 // replace values greater than 9 in v3 with 100
std::replace_if( v3.begin(), v3.end(), greater9, 100 ); 53
cout << "\nVector v3 after replacing all values greater"
<< "\nthan 9 with 100s:\n ";
std::copy( v3.begin(), v3.end(), output ); 57
std::vector< int > v4( a, a + SIZE );
std::vector< int > c2( SIZE ); 60
cout << "\n\nVector v4 before replacing all values greater "
<< "than 9 and copying:\n ";
std::copy( v4.begin(), v4.end(), output ); 64
// copy v4 to c2, replacing elements greater than 9 with 100
std::replace_copy_if(
v4.begin(), v4.end(), c2.begin(), greater9, 100 ); 68
cout << "\nVector c2 after replacing all values greater "
<< "than 9 in v4:\n ";
std::copy( c2.begin(), c2.end(), output ); 72
cout << endl; 74
return 0; 76
77 } // end main
fig21_29.cpp (3 of 4)

98. fig21_29.cpp (4 of 4) fig21_29.cpp output (1 of 1)78
79 // determine whether argument is greater than 9
80 bool greater9( int x )
81 {
return x > 9; 83
84 } // end function greater9
fig21_29.cpp (4 of 4) fig21_29.cpp output (1 of 1)
Vector v1 before replacing all 10s:
Vector v1 after replacing 10s with 100s:
Vector v2 before replacing all 10s and copying:
Vector c1 after replacing all 10s in v2:
Vector v3 before replacing values greater than 9:
Vector v3 after replacing all values greater
than 9 with 100s:
Vector v4 before replacing all values greater than 9 and copying:
Vector c2 after replacing all values greater than 9 in v4:

99. 21.5.5 Mathematical Algorithms
random_shuffle(iter1, iter2)
Randomly mixes elements in range
count(iter1, iter2, value)
Returns number of instances of value in range
count_if(iter1, iter2, function)
Counts number of instances that return true
min_element(iter1, iter2)
Returns iterator to smallest element
max_element(iter1, iter2)
Returns iterator to largest element

100. 21.5.5 Mathematical Algorithms
accumulate(iter1, iter2)
Returns sum of elements in range
for_each(iter1, iter2, function)
Calls function on every element in range
Does not modify element
transform(iter1, iter2, iter3, function)
Calls function for all elements in range of iter1-iter2, copies result to iter3

101. fig21_30.cpp (1 of 5) 1 // Fig. 21.30: fig21_30.cpp
// Mathematical algorithms of the standard library.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <algorithm> // algorithm definitions
#include <numeric> // accumulate is defined here
10 #include <vector> 11
12 bool greater9( int );
13 void outputSquare( int );
14 int calculateCube( int ); 15
16 int main()
17 {
const int SIZE = 10;
int a1[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 20
std::vector< int > v( a1, a1 + SIZE );
std::ostream_iterator< int > output( cout, " " ); 23
cout << "Vector v before random_shuffle: ";
std::copy( v.begin(), v.end(), output ); 26
fig21_30.cpp (1 of 5)

102. fig21_30.cpp (2 of 5) 27 // shuffle elements of v
std::random_shuffle( v.begin(), v.end() ); 29
cout << "\nVector v after random_shuffle: ";
std::copy( v.begin(), v.end(), output ); 32
int a2[] = { 100, 2, 8, 1, 50, 3, 8, 8, 9, 10 };
std::vector< int > v2( a2, a2 + SIZE ); 35
cout << "\n\nVector v2 contains: ";
std::copy( v2.begin(), v2.end(), output ); 38
// count number of elements in v2 with value 8
int result = std::count( v2.begin(), v2.end(), 8 ); 41
std::cout << "\nNumber of elements matching 8: " << result; 43
// count number of elements in v2 that are greater than 9
result = std::count_if( v2.begin(), v2.end(), greater9 ); 46
cout << "\nNumber of elements greater than 9: " << result; 48
fig21_30.cpp (2 of 5)

103. fig21_30.cpp (3 of 5) 49 // locate minimum element in v2
cout << "\n\nMinimum element in Vector v2 is: "
<< *( std::min_element( v2.begin(), v2.end() ) ); 52
// locate maximum element in v2
cout << "\nMaximum element in Vector v2 is: "
<< *( std::max_element( v2.begin(), v2.end() ) ); 56
// calculate sum of elements in v
cout << "\n\nThe total of the elements in Vector v is: "
<< std::accumulate( v.begin(), v.end(), 0 ); 60
cout << "\n\nThe square of every integer in Vector v is:\n"; 62
// output square of every element in v
std::for_each( v.begin(), v.end(), outputSquare ); 65
std::vector< int > cubes( SIZE ); 67
// calculate cube of each element in v;
// place results in cubes
std::transform(
v.begin(), v.end(), cubes.begin(), calculateCube );
fig21_30.cpp (3 of 5)

104. 72
cout << "\n\nThe cube of every integer in Vector v is:\n";
std::copy( cubes.begin(), cubes.end(), output ); 75
cout << endl; 77
return 0; 79
80 } // end main 81
82 // determine whether argument is greater than 9
83 bool greater9( int value )
84 {
return value > 9; 86
87 } // end function greater9 88
89 // output square of argument
90 void outputSquare( int value )
91 {
cout << value * value << ' '; 93
94 } // end function outputSquare 95
fig21_30.cpp (4 of 5)

105. fig21_30.cpp (5 of 5) fig21_30.cpp output (1 of 1)
96 // return cube of argument
97 int calculateCube( int value )
98 {
return value * value * value;
100
101 } // end function calculateCube
fig21_30.cpp (5 of 5) fig21_30.cpp output (1 of 1)
Vector v before random_shuffle:
Vector v after random_shuffle:
Vector v2 contains:
Number of elements matching 8: 3
Number of elements greater than 9: 3
Minimum element in Vector v2 is: 1
Maximum element in Vector v2 is: 100
The total of the elements in Vector v is: 55
The square of every integer in Vector v is:
The cube of every integer in Vector v is:

106. 21.5.6 Basic Searching and Sorting Algorithms
find(iter1, iter2, value)
Returns iterator to first instance of value (in range)
find_if(iter1, iter2, function)
Like find
Returns iterator when function returns true
sort(iter1, iter2)
Sorts elements in ascending order
binary_search(iter1, iter2, value)
Searches ascending sorted list for value
Uses binary search

107. fig21_31.cpp (1 of 4) 1 // Fig. 21.31: fig21_31.cpp
// Standard library search and sort algorithms.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <algorithm> // algorithm definitions
#include <vector> // vector class-template definition 10
11 bool greater10( int value ); // prototype 12
13 int main()
14 {
const int SIZE = 10;
int a[ SIZE ] = { 10, 2, 17, 5, 16, 8, 13, 11, 20, 7 }; 17
std::vector< int > v( a, a + SIZE );
std::ostream_iterator< int > output( cout, " " ); 20
cout << "Vector v contains: ";
std::copy( v.begin(), v.end(), output ); 23
// locate first occurrence of 16 in v
std::vector< int >::iterator location;
location = std::find( v.begin(), v.end(), 16 );
fig21_31.cpp (1 of 4)

108. fig21_31.cpp (2 of 4) 27 28 if ( location != v.end() )
cout << "\n\nFound 16 at location "
<< ( location - v.begin() );
else
cout << "\n\n16 not found"; 33
// locate first occurrence of 100 in v
location = std::find( v.begin(), v.end(), 100 ); 36
if ( location != v.end() )
cout << "\nFound 100 at location "
<< ( location - v.begin() );
else
cout << "\n100 not found"; 42
// locate first occurrence of value greater than 10 in v
location = std::find_if( v.begin(), v.end(), greater10 ); 45
if ( location != v.end() )
cout << "\n\nThe first value greater than 10 is "
<< *location << "\nfound at location "
<< ( location - v.begin() );
else
cout << "\n\nNo values greater than 10 were found"; 52
fig21_31.cpp (2 of 4)

109. fig21_31.cpp (3 of 4) 53 // sort elements of v
std::sort( v.begin(), v.end() ); 55
cout << "\n\nVector v after sort: ";
std::copy( v.begin(), v.end(), output ); 58
// use binary_search to locate 13 in v
if ( std::binary_search( v.begin(), v.end(), 13 ) )
cout << "\n\n13 was found in v";
else
cout << "\n\n13 was not found in v"; 64
// use binary_search to locate 100 in v
if ( std::binary_search( v.begin(), v.end(), 100 ) )
cout << "\n100 was found in v";
else
cout << "\n100 was not found in v"; 70
cout << endl; 72
return 0; 74
75 } // end main 76
fig21_31.cpp (3 of 4)

110. fig21_31.cpp (4 of 4) fig21_31.cpp output (1 of 1)
77 // determine whether argument is greater than 10
78 bool greater10( int value )
79 {
return value > 10; 81
82 } // end function greater10
fig21_31.cpp (4 of 4) fig21_31.cpp output (1 of 1)
Vector v contains:
Found 16 at location 4
100 not found
The first value greater than 10 is 17
found at location 2
Vector v after sort:
13 was found in v
100 was not found in v

111. 21.5.7 swap, iter_swap and swap_ranges
swap(element1, element2)
Exchanges two values
swap( a[ 0 ], a[ 1 ] );
iter_swap(iter1, iter2)
Exchanges the values to which the iterators refer
swap_ranges(iter1, iter2, iter3)
Swap the elements from iter1-iter2 with elements beginning at iter3

112. fig21_32.cpp (1 of 2) 1 // Fig. 21.32: fig21_32.cpp
// Standard library algorithms iter_swap, swap and swap_ranges.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <algorithm> // algorithm definitions 9
10 int main()
11 {
const int SIZE = 10;
int a[ SIZE ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
std::ostream_iterator< int > output( cout, " " ); 15
cout << "Array a contains:\n ";
std::copy( a, a + SIZE, output ); 18
// swap elements at locations 0 and 1 of array a
std::swap( a[ 0 ], a[ 1 ] ); 21
cout << "\nArray a after swapping a[0] and a[1] "
<< "using swap:\n ";
std::copy( a, a + SIZE, output ); 25
fig21_32.cpp (1 of 2)

113. 26 // use iterators to swap elements at locations
// 0 and 1 of array a
std::iter_swap( &a[ 0 ], &a[ 1 ] );
cout << "\nArray a after swapping a[0] and a[1] "
<< "using iter_swap:\n ";
std::copy( a, a + SIZE, output ); 32
// swap elements in first five elements of array a with
// elements in last five elements of array a
std::swap_ranges( a, a + 5, a + 5 ); 36
cout << "\nArray a after swapping the first five elements\n"
<< "with the last five elements:\n ";
std::copy( a, a + SIZE, output ); 40
cout << endl; 42
return 0; 44
45 } // end main
fig21_32.cpp (2 of 2)

114. fig21_32.cpp output (1 of 1) Array a contains: 1 2 3 4 5 6 7 8 9 10
Array a after swapping a[0] and a[1] using swap:
Array a after swapping a[0] and a[1] using iter_swap:
Array a after swapping the first five elements
with the last five elements:
fig21_32.cpp output (1 of 1)

115. 21.5.8 copy_backward, merge, unique and reverse
copy_backward(iter1, iter2, iter3)
Copy elements from iter1-iter2 to iter3, in reverse order
merge(iter1, iter2, iter3, iter4, iter5)
Ranges iter1-iter2 and iter3-iter4 must be sorted in ascending order
merge copies both lists into iter5, in ascending order
unique(iter1, iter2)
Removes duplicate elements from a sorted list
Returns iterator to new end of sequence
reverse(iter1, iter2)
Reverses elements from iter1-iter2

116. fig21_33.cpp (1 of 3) 1 // Fig. 21.33: fig21_33.cpp
// Standard library functions copy_backward, merge,
// unique and reverse.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition 11
12 int main()
13 {
const int SIZE = 5;
int a1[ SIZE ] = { 1, 3, 5, 7, 9 };
int a2[ SIZE ] = { 2, 4, 5, 7, 9 }; 17
std::vector< int > v1( a1, a1 + SIZE );
std::vector< int > v2( a2, a2 + SIZE ); 20
std::ostream_iterator< int > output( cout, " " ); 22
cout << "Vector v1 contains: ";
std::copy( v1.begin(), v1.end(), output );
cout << "\nVector v2 contains: ";
std::copy( v2.begin(), v2.end(), output );
fig21_33.cpp (1 of 3)

117. 27
std::vector< int > results( v1.size() ); 29
// place elements of v1 into results in reverse order
std::copy_backward( v1.begin(), v1.end(), results.end() ); 32
cout << "\n\nAfter copy_backward, results contains: ";
std::copy( results.begin(), results.end(), output ); 35
std::vector< int > results2( v1.size() + v2.size() ); 37
// merge elements of v1 and v2 into results2 in sorted order
std::merge( v1.begin(), v1.end(), v2.begin(), v2.end(),
results2.begin() ); 41
cout << "\n\nAfter merge of v1 and v2 results2 contains:\n";
std::copy( results2.begin(), results2.end(), output ); 44
// eliminate duplicate values from results2
std::vector< int >::iterator endLocation;
endLocation =
std::unique( results2.begin(), results2.end() ); 49
cout << "\n\nAfter unique results2 contains:\n";
std::copy( results2.begin(), endLocation, output ); 52
fig21_33.cpp (2 of 3)

118. fig21_33.cpp (3 of 3) fig21_33.cpp output (1 of 1)
cout << "\n\nVector v1 after reverse: "; 54
// reverse elements of v1
std::reverse( v1.begin(), v1.end() ); 57
std::copy( v1.begin(), v1.end(), output ); 59
cout << endl; 61
return 0; 63
64 } // end main
fig21_33.cpp (3 of 3) fig21_33.cpp output (1 of 1)
Vector v1 contains:
Vector v2 contains:
After copy_backward, results contains:
After merge of v1 and v2 results2 contains:
After unique results2 contains:
Vector v1 after reverse:

119. 21.5.9 inplace_merge, unique_copy and reverse_copy
inplace_merge(iter1, iter2, iter3)
Merges two sorted sequences (iter1-iter2, iter2-iter3) inside the same container
unique_copy(iter1, iter2, iter3)
Copies all unique elements in sorted array (from iter1-iter2) into iter3
reverse_copy(iter1, iter2, iter3)
Reverses elements in iter1-iter2, copies into iter3

120. fig21_34.cpp (1 of 2) 1 // Fig. 21.34: fig21_34.cpp
// Standard library algorithms inplace_merge,
// reverse_copy and unique_copy.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition
11 #include <iterator> // back_inserter definition 12
13 int main()
14 {
const int SIZE = 10;
int a1[ SIZE ] = { 1, 3, 5, 7, 9, 1, 3, 5, 7, 9 };
std::vector< int > v1( a1, a1 + SIZE ); 18
std::ostream_iterator< int > output( cout, " " ); 20
cout << "Vector v1 contains: ";
std::copy( v1.begin(), v1.end(), output ); 23
// merge first half of v1 with second half of v1 such that
// v1 contains sorted set of elements after merge
std::inplace_merge( v1.begin(), v1.begin() + 5, v1.end() ); 27
fig21_34.cpp (1 of 2)

121. 28 cout << "\nAfter inplace_merge, v1 contains: ";
std::copy( v1.begin(), v1.end(), output ); 30
std::vector< int > results1; 32
// copy only unique elements of v1 into results1
std::unique_copy(
v1.begin(), v1.end(), std::back_inserter( results1 ) ); 36
cout << "\nAfter unique_copy results1 contains: ";
std::copy( results1.begin(), results1.end(), output ); 39
std::vector< int > results2; 41
cout << "\nAfter reverse_copy, results2 contains: "; 43
// copy elements of v1 into results2 in reverse order
std::reverse_copy(
v1.begin(), v1.end(), std::back_inserter( results2 ) ); 47
std::copy( results2.begin(), results2.end(), output ); 49
cout << endl; 51
return 0; 53
54 } // end main
fig21_34.cpp (2 of 2)

122. fig21_34.cpp output (1 of 1) Vector v1 contains: 1 3 5 7 9 1 3 5 7 9
After inplace_merge, v1 contains:
After unique_copy results1 contains:
After reverse_copy, results2 contains:
fig21_34.cpp output (1 of 1)

123. 21.5.10 Set Operations includes(iter1, iter2, iter3, iter4)
Returns true if iter1-iter2 contains iter3-iter4
Both ranges must be sorted
a1:
a2: 1 3
a1 includes a3
set_difference(iter1, iter2, iter3, iter4, iter5)
Copies elements in first set (1-2) that are not in second set (3-4) into iter5
set_intersection(iter1, iter2, iter3, iter4, iter5)
Copies common elements from the two sets (1-2, 3-4) into iter5

124. Set Operations
set_symmetric_difference(iter1, iter2, iter3, iter4, iter5)
Copies elements in set (1-2) but not set (3-4), and vice versa, into iter5
a1:
a2:
set_symmetric_difference:
Both sets must be sorted
set_union( iter1, iter2, iter3, iter4, iter5)
Copies elements in either or both sets to iter5

125. fig21_35.cpp (1 of 3) 1 // Fig. 21.35: fig21_35.cpp
// Standard library algorithms includes, set_difference,
// set_intersection, set_symmetric_difference and set_union.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions 10
11 int main()
12 {
const int SIZE1 = 10, SIZE2 = 5, SIZE3 = 20;
int a1[ SIZE1 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int a2[ SIZE2 ] = { 4, 5, 6, 7, 8 };
int a3[ SIZE2 ] = { 4, 5, 6, 11, 15 };
std::ostream_iterator< int > output( cout, " " ); 18
cout << "a1 contains: ";
std::copy( a1, a1 + SIZE1, output );
cout << "\na2 contains: ";
std::copy( a2, a2 + SIZE2, output );
cout << "\na3 contains: ";
std::copy( a3, a3 + SIZE2, output ); 25
fig21_35.cpp (1 of 3)

126. 26 // determine whether set a2 is completely contained in a1
if ( std::includes( a1, a1 + SIZE1, a2, a2 + SIZE2 ) )
cout << "\n\na1 includes a2";
else
cout << "\n\na1 does not include a2"; 31
// determine whether set a3 is completely contained in a1
if ( std::includes( a1, a1 + SIZE1, a3, a3 + SIZE2 ) )
cout << "\na1 includes a3";
else
cout << "\na1 does not include a3"; 37
int difference[ SIZE1 ]; 39
// determine elements of a1 not in a2
int *ptr = std::set_difference( a1, a1 + SIZE1,
a2, a2 + SIZE2, difference ); 43
cout << "\n\nset_difference of a1 and a2 is: ";
std::copy( difference, ptr, output ); 46
int intersection[ SIZE1 ]; 48
// determine elements in both a1 and a2
ptr = std::set_intersection( a1, a1 + SIZE1,
a2, a2 + SIZE2, intersection ); 52
fig21_35.cpp (2 of 3)

127. 53 cout << "\n\nset_intersection of a1 and a2 is: ";
std::copy( intersection, ptr, output ); 55
int symmetric_difference[ SIZE1 ]; 57
// determine elements of a1 that are not in a2 and
// elements of a2 that are not in a1
ptr = std::set_symmetric_difference( a1, a1 + SIZE1,
a2, a2 + SIZE2, symmetric_difference ); 62
cout << "\n\nset_symmetric_difference of a1 and a2 is: ";
std::copy( symmetric_difference, ptr, output ); 65
int unionSet[ SIZE3 ]; 67
// determine elements that are in either or both sets
ptr = std::set_union( a1, a1 + SIZE1,
a3, a3 + SIZE2, unionSet ); 71
cout << "\n\nset_union of a1 and a3 is: ";
std::copy( unionSet, ptr, output ); 74
cout << endl; 76
return 0; 78
79 } // end main
fig21_35.cpp (3 of 3)

128. fig21_35.cpp output (1 of 1) a1 contains: 1 2 3 4 5 6 7 8 9 10
a1 includes a2
a1 does not include a3
set_difference of a1 and a2 is:
set_intersection of a1 and a2 is:
set_symmetric_difference of a1 and a2 is:
set_union of a1 and a3 is:
fig21_35.cpp output (1 of 1)

129. 21.5.11 lower_bound, upper_bound and equal_range
lower_bound(iter1, iter2, value)
For sorted elements, returns iterator to the first location where value could be inserted and elements remain sorted
upper_bound(iter1, iter2, value)
Same as lower_bound, but returns iterator to last element where value could be inserted
equal_range(iter1, iter2, value)
Returns two iterators, a lower_bound and an upper_bound
Assign them to a pair object

130. fig21_36.cpp (1 of 4) 1 // Fig. 21.36: fig21_36.cpp
// Standard library functions lower_bound, upper_bound and
// equal_range for a sorted sequence of values.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm> // algorithm definitions
10 #include <vector> // vector class-template definition 11
12 int main()
13 {
const int SIZE = 10;
int a1[] = { 2, 2, 4, 4, 4, 6, 6, 6, 6, 8 };
std::vector< int > v( a1, a1 + SIZE );
std::ostream_iterator< int > output( cout, " " ); 18
cout << "Vector v contains:\n";
std::copy( v.begin(), v.end(), output ); 21
// determine lower-bound insertion point for 6 in v
std::vector< int >::iterator lower;
lower = std::lower_bound( v.begin(), v.end(), 6 ); 25
fig21_36.cpp (1 of 4)

131. 26 cout << "\n\nLower bound of 6 is element "
<< ( lower - v.begin() ) << " of vector v"; 28
// determine upper-bound insertion point for 6 in v
std::vector< int >::iterator upper;
upper = std::upper_bound( v.begin(), v.end(), 6 ); 32
cout << "\nUpper bound of 6 is element "
<< ( upper - v.begin() ) << " of vector v"; 35
// use equal_range to determine both the lower- and
// upper-bound insertion points for 6
std::pair< std::vector< int >::iterator,
std::vector< int >::iterator > eq;
eq = std::equal_range( v.begin(), v.end(), 6 ); 41
cout << "\nUsing equal_range:\n"
<< " Lower bound of 6 is element "
<< ( eq.first - v.begin() ) << " of vector v";
cout << "\n Upper bound of 6 is element "
<< ( eq.second - v.begin() ) << " of vector v"; 47
cout << "\n\nUse lower_bound to locate the first point\n"
<< "at which 5 can be inserted in order"; 50
fig21_36.cpp (2 of 4)

132. 51 // determine lower-bound insertion point for 5 in v
lower = std::lower_bound( v.begin(), v.end(), 5 ); 53
cout << "\n Lower bound of 5 is element "
<< ( lower - v.begin() ) << " of vector v"; 56
cout << "\n\nUse upper_bound to locate the last point\n"
<< "at which 7 can be inserted in order"; 59
// determine upper-bound insertion point for 7 in v
upper = std::upper_bound( v.begin(), v.end(), 7 ); 62
cout << "\n Upper bound of 7 is element "
<< ( upper - v.begin() ) << " of vector v"; 65
cout << "\n\nUse equal_range to locate the first and\n"
<< "last point at which 5 can be inserted in order"; 68
// use equal_range to determine both the lower- and
// upper-bound insertion points for 5
eq = std::equal_range( v.begin(), v.end(), 5 ); 72
cout << "\n Lower bound of 5 is element "
<< ( eq.first - v.begin() ) << " of vector v";
cout << "\n Upper bound of 5 is element "
<< ( eq.second - v.begin() ) << " of vector v"
<< endl;
fig21_36.cpp (3 of 4)

133. fig21_36.cpp (4 of 4) fig21_36.cpp output (1 of 1)78
return 0; 80
81 } // end main
fig21_36.cpp (4 of 4) fig21_36.cpp output (1 of 1)
Vector v contains:
Lower bound of 6 is element 5 of vector v
Upper bound of 6 is element 9 of vector v
Using equal_range:
Use lower_bound to locate the first point
at which 5 can be inserted in order
Lower bound of 5 is element 5 of vector v
Use upper_bound to locate the last point
at which 7 can be inserted in order
Upper bound of 7 is element 9 of vector v
Use equal_range to locate the first and
last point at which 5 can be inserted in order
Upper bound of 5 is element 5 of vector v

134. Heapsort - sorting algorithm
Heap binary tree
Largest element at top of heap
Children always less than parent node
make_heap(iter1, iter2)
Creates a heap in the range of the iterators
Must be random access iterators (arrays, vectors, deques)
sort_heap(iter1, iter2)
Sorts a heap sequence from iter1 to iter2

135. 21.5.12 Heapsort Functions push_heap(iter1, iter2)
The iterators must specify a heap
Adds last element in object to heap
Assumes other elements already in heap order
pop_heap(iter1, iter2)
Removes the top element of a heap and puts it at the end of the container.
Function checks that all other elements still in a heap
Range of the iterators must be a heap.
If all the elements popped, sorted list

136. fig21_37.cpp (1 of 3) Create a new heap. 1 // Fig. 21.37: fig21_37.cpp
// Standard library algorithms push_heap, pop_heap,
// make_heap and sort_heap.
#include <iostream> 5
using std::cout;
using std::endl; 8
#include <algorithm>
10 #include <vector> 11
12 int main()
13 {
const int SIZE = 10;
int a[ SIZE ] = { 3, 100, 52, 77, 22, 31, 1, 98, 13, 40 };
std::vector< int > v( a, a + SIZE ), v2;
std::ostream_iterator< int > output( cout, " " ); 18
cout << "Vector v before make_heap:\n";
std::copy( v.begin(), v.end(), output ); 21
// create heap from vector v
std::make_heap( v.begin(), v.end() ); 24
cout << "\nVector v after make_heap:\n";
std::copy( v.begin(), v.end(), output );
fig21_37.cpp (1 of 3)
Create a new heap.

137. Add elements one at a time.27
// sort elements of v with sort_heap
std::sort_heap( v.begin(), v.end() ); 30
cout << "\nVector v after sort_heap:\n";
std::copy( v.begin(), v.end(), output ); 33
// perform the heapsort with push_heap and pop_heap
cout << "\n\nArray a contains: ";
std::copy( a, a + SIZE, output ); 37
cout << endl; 39
// place elements of array a into v2 and
// maintain elements of v2 in heap
for ( int i = 0; i < SIZE; ++i ) {
v2.push_back( a[ i ] );
std::push_heap( v2.begin(), v2.end() );
cout << "\nv2 after push_heap(a[" << i << "]): ";
std::copy( v2.begin(), v2.end(), output ); 47
} // end for 49
cout << endl; 51
fig21_37.cpp (2 of 3)
Add elements one at a time.

138. fig21_37.cpp (3 of 3) 52 // remove elements from heap in sorted order
for ( int j = 0; j < v2.size(); ++j ) {
cout << "\nv2 after " << v2[ 0 ] << " popped from heap\n";
std::pop_heap( v2.begin(), v2.end() - j );
std::copy( v2.begin(), v2.end(), output ); 57
} // end for 59
cout << endl; 61
return 0; 63
64 } // end main
fig21_37.cpp (3 of 3)

139. fig21_37.cpp output (1 of 2) Vector v before make_heap:
Vector v after make_heap:
Vector v after sort_heap:
Array a contains:
v2 after push_heap(a[0]): 3
v2 after push_heap(a[1]): 100 3
v2 after push_heap(a[2]):
v2 after push_heap(a[3]):
v2 after push_heap(a[4]):
v2 after push_heap(a[5]):
v2 after push_heap(a[6]):
v2 after push_heap(a[7]):
v2 after push_heap(a[8]):
v2 after push_heap(a[9]):
fig21_37.cpp output (1 of 2)

140. fig21_37.cpp output (2 of 2) v2 after 100 popped from heap
v2 after 98 popped from heap
v2 after 77 popped from heap
v2 after 52 popped from heap
v2 after 40 popped from heap
v2 after 31 popped from heap
v2 after 22 popped from heap
v2 after 13 popped from heap
v2 after 3 popped from heap
v2 after 1 popped from heap
fig21_37.cpp output (2 of 2)

141. 21.5.13 min and max min(value1, value2) max(value1, value2)
Returns smaller element
max(value1, value2)
Returns larger element

142. fig21_38.cpp (1 of 1) 1 // Fig. 21.38: fig21_38.cpp
// Standard library algorithms min and max.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <algorithm> 9
10 int main()
11 {
cout << "The minimum of 12 and 7 is: "
<< std::min( 12, 7 );
cout << "\nThe maximum of 12 and 7 is: "
<< std::max( 12, 7 );
cout << "\nThe minimum of 'G' and 'Z' is: "
<< std::min( 'G', 'Z' );
cout << "\nThe maximum of 'G' and 'Z' is: "
<< std::max( 'G', 'Z' ) << endl; 20
return 0; 22
23 } // end main
fig21_38.cpp (1 of 1)

143. fig21_38.cpp output (1 of 1) The minimum of 12 and 7 is: 7
The maximum of 12 and 7 is: 12
The minimum of 'G' and 'Z' is: G
The maximum of 'G' and 'Z' is: Z
fig21_38.cpp output (1 of 1)

144. 21.5.14 Algorithms Not Covered in This Chapter
adjacent_difference
inner_product
partial_sum
nth_element
partition
stable_partition
next_permutation
prev_permutation
rotate
rotate_copy
adjacent_find
partial_sort
partial_sort_copy
stable_sort

145. 21.6 Class bitset Operations Class bitset
Represents a set of bit flags
Can manipulate bit sets
Operations
bitset <size> b; create bitset
b.set( bitNumber) set bit bitNumber to on
b.set() all bits on
b.reset(bitNumber) set bit bitNumber to off
b.reset() all bits off
b.flip(bitNumber) flip bit (on to off, off to on)
b.flip() flip all bits
b[bitNumber] returns reference to bit
b.at(bitNumber) range checking, returns reference

146. 21.6 Class bitset Operations
b.test(bitNumber) has range checking; if bit on, returns true
b.size() size of bitset
b.count() number of bits set to on
b.any() true if any bits are on
b.none() true if no bits are on
can use &=, |=, !=, <<=, >>=
b &= b1
Logical AND between b and b1, result in b
b.to_string() convert to string
b.to_ulong() convert to long

147. fig21_40.cpp (1 of 3) 1 // Fig. 21.40: fig21_40.cpp
// Using a bitset to demonstrate the Sieve of Eratosthenes.
#include <iostream> 4
using std::cin;
using std::cout;
using std::endl; 8
#include <iomanip> 10
11 using std::setw; 12
13 #include <bitset> // bitset class definition
14 #include <cmath> // sqrt prototype 15
16 int main()
17 {
const int size = 1024;
int value;
std::bitset< size > sieve; 21
sieve.flip(); 23
fig21_40.cpp (1 of 3)

148. 24 // perform Sieve of Eratosthenes
int finalBit = sqrt( sieve.size() ) + 1; 26
for ( int i = 2; i < finalBit; ++i ) 28
if ( sieve.test( i ) ) 30
for ( int j = 2 * i; j < size; j += i )
sieve.reset( j ); 33
cout << "The prime numbers in the range 2 to 1023 are:\n"; 35
// display prime numbers in range
for ( int k = 2, counter = 0; k < size; ++k ) 38
if ( sieve.test( k ) ) {
cout << setw( 5 ) << k; 41
if ( ++counter % 12 == 0 )
cout << '\n'; 44
} // end outer if 46
cout << endl; 48
Sieve of Eratosthenes: turn off bits for all multiples of a number. What bits remain are prime.
fig21_40.cpp (2 of 3)

149. 49 // get value from user to determine whether value is prime
cout << "\nEnter a value from 1 to 1023 (-1 to end): ";
cin >> value; 52
while ( value != -1 ) { 54
if ( sieve[ value ] )
cout << value << " is a prime number\n";
else
cout << value << " is not a prime number\n"; 59
cout << "\nEnter a value from 2 to 1023 (-1 to end): ";
cin >> value; 62
} // end while 64
return 0; 66
67 } // end main
fig21_40.cpp (3 of 3)

150. The prime numbers in the range 2 to 1023 are:
Enter a value from 1 to 1023 (-1 to end): 389
389 is a prime number
Enter a value from 2 to 1023 (-1 to end): 88
88 is not a prime number
Enter a value from 2 to 1023 (-1 to end): -1
fig21_40.cpp output (1 of 1)

151. Function objects (<functional>)
Contain functions invoked using operator()

152. Create a function to be used with accumulate.
// Fig : fig21_42.cpp
// Demonstrating function objects.
#include <iostream> 4
using std::cout;
using std::endl; 7
#include <vector> // vector class-template definition
#include <algorithm> // copy algorithm
10 #include <numeric> // accumulate algorithm
11 #include <functional> // binary_function definition 12
13 // binary function adds square of its second argument and
14 // running total in its first argument, then returns sum
15 int sumSquares( int total, int value )
16 {
return total + value * value; 18
19 } // end function sumSquares 20
fig21_42.cpp (1 of 4)
Create a function to be used with accumulate.

153. 21 // binary function class template defines overloaded operator()
22 // that adds suare of its second argument and running total in
23 // its first argument, then returns sum
24 template< class T >
25 class SumSquaresClass : public std::binary_function< T, T, T > { 26
27 public: 28
// add square of value to total and return result
const T operator()( const T &total, const T &value ) {
return total + value * value; 33
} // end function operator() 35
36 }; // end class SumSquaresClass 37
fig21_42.cpp (2 of 4)
Create a function object (it can also encapsulate data). Overload operator().

154. 38 int main()
39 {
const int SIZE = 10;
int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 42
std::vector< int > integers( array, array + SIZE ); 44
std::ostream_iterator< int > output( cout, " " ); 46
int result = 0; 48
cout << "vector v contains:\n";
std::copy( integers.begin(), integers.end(), output ); 51
// calculate sum of squares of elements of vector integers
// using binary function sumSquares
result = std::accumulate( integers.begin(), integers.end(),
, sumSquares ); 56
cout << "\n\nSum of squares of elements in integers using "
<< "binary\nfunction sumSquares: " << result; 59
fig21_42.cpp (3 of 4)
accumulate initially passes 0 as the first argument, with the first element as the second. It then uses the return value as the first argument, and iterates through the other elements.

155. fig21_42.cpp (4 of 4) fig21_42.cpp output (1 of 1)
// calculate sum of squares of elements of vector integers
// using binary-function object
result = std::accumulate( integers.begin(), integers.end(),
, SumSquaresClass< int >() ); 64
cout << "\n\nSum of squares of elements in integers using "
<< "binary\nfunction object of type "
<< "SumSquaresClass< int >: " << result << endl; 68
return 0; 70
71 } // end main
fig21_42.cpp (4 of 4) fig21_42.cpp output (1 of 1)
Use accumulate with a function object.
vector v contains:
Sum of squares of elements in integers using binary
function sumSquares: 385
function object of type SumSquaresClass< int >: 385