CSS 342 DATA STRUCTURES, ALGORITHMS, AND DISCRETE MATHEMATICS I LECTURE C++ INTERLUDE 1.3. C++ BOOK.

Announcements Agenda: C++ Templates: functions and class Examples: Vector, Swap, Bubble Sort, Insertion Sort Review Assignment 2 Time Permitting: Object lifetimes, Arrays, Pointer Review

Vectors #include Using namespace std; main () { vector first; // empty vector of ints vector second (4,100); // four ints with value 100 vector third (second.begin(),second.end()); // iterating through second vector fourth (third); // a copy of third for (int i=0; i < second.size(); i++) { cout << second.at(i); cout << second[i]; } second.push_back(56); second.pop_back(); }

Vectors Excellent data structure choice Fast, safe-access, good memory characteristics Built on dynamic array Templatized so that vector vFoo(4, foos); vector birds(3, eagle);

#include "Bird.h" #include int main() { Bird b1("eagle"); Bird b2 = b1; vector birds; vector birds2(4, b2); vector birds3(birds2); birds2.push_back(Bird("penguin")); for (int i = 0; i < birds2.size(); i++) { cout << birds2[i].getName() << endl; } return 0; }

Templates Polymorphism Allows for multiple types to be passed to function or class One set of code works across all types Works on Function or Class level Syntax: template ItemType is the type utilized throughout code Function/Class must be able to handle the types utilized

Why Object Oriented Programming (OOP)? Abstraction Encapsulation Hierarchy Polymorphism

Let’s templatize a function

int main() { double a = 3; double b = 7; cout << "a = " << a << " b = " << b << endl; swap(a, b); cout << "a = " << a << " b = " << b << endl; cin >> a; return 0; } void swap(double &a, double &b) { int temp; temp = a; a = b; b = temp; return; } Swap (w/doubles)

template void swapAll(ItemType &, ItemType &); int main() { double aDouble = 3, bDouble = 7; int aInt = 5, bInt = 13; string aString("First"), bString("Second"); cout << "aDouble = " << aDouble << " bDouble = " << bDouble << std::endl; swapAll(aDouble, bDouble); cout << "aDouble = " << aDouble << " bDouble = " << bDouble << std::endl; cout << "aInt = " << aInt << " bInt = " << bInt << endl; swapAll(aInt, bInt); cout << "aInt = " << aInt << " bInt = " << bInt << endl; cout << "aString = " << aString << " bString = " << bString << endl; swapAll(aString, bString); cout << "aString = " << aString << " bString = " << bString << endl; return 0; } template void swapAll(ItemType &a, ItemType &b) { ItemType temp; temp = a; a = b; b = temp; return; } Swap w/Templates

Computer Scientist of the week Grace Hopper Invented the first compiler United States Navy Rear Admiral Promoted the idea of machine independent languages Key inventor of COBOL Popularized the term debugging Advocated for Navy to move from centralized computers to distributed computers in the 1970s

Let’s templatize a class SORTED SET OF ITEMS

SortedList: Class Template Example Example to show templates on a class which keeps a sorted set of items Add an item Print out items Sort Bonus Points: concatenate two lists Data Structure: Vector Sort Will show BubbleSort and Insertion sort algorithm

#ifndef SORTED_LIST_CPP #define SORTED_LIST_CPP #include "SortedList.h" template SortedList ::SortedList(){ } template void SortedList ::Add(const ItemType &item) { thelist.push_back(item); return; } template void SortedList ::Print() const { for (int i = 0; i < thelist.size(); i++) { cout << thelist[i] << endl; } #endif #ifndef SORTED_LIST_H #define SORTED_LIST_H #include using namespace std; template class SortedList { public: SortedList(); ~SortedList(); void Add(const ItemType &item); void Print() const; void Sort(); private: vector thelist; }; #include "SortedList.cpp" #endif

Bubblesort or Sinking Sort Used to sort an array of items by traversing (n-1) times and bubbling largest current item to the bottom Graphical Representation : example-300px.gif example-300px.gif Bad memory and speed characteristics. “the bubble sort seems to have nothing to recommend it, except a catchy name and the fact that it leads to some interesting theoretical problems“, Donald Knuth

Insertion Sort SortedUnsorted Copy 10 Shift 29 Insert 10, copy 14 Shift 29 Insert 14; copy 37 Insert 37; Copy 13 Shift 37, 29 and 14. Insert Shift nothing unsortedTop Or Carranno , Or:

template void SortedList ::Sort() { for (int place = 1; place < thelist.size(); place++) { ItemType temp = thelist[place]; int i = place; while ((i > 0) && (thelist[i-1] > temp)) { thelist[i] = thelist[i-1]; i--; } thelist[i] = temp; } Function for Insertion Sort

Review Assignment 2

C++ Fundamentals

Time of Invocation (constructors) Automatic Local Each time block is executed Static Local Once –first time it is hit Global In order of declaration in translation unit Typically before main() is entered Destroyed in reverse order of construction Dynamic (tbd) malloc/free new/delete

Arrays Arrays: reservation and construction of indexed set of objects or built-in types int x=5; int arr1[100] int arr2[3] = {34, 7, 34}; char cArr1[7]; char cArr2[10][5]; arr1[x] = 32; arr2[0] = arr1[x]; cArr2[3][3] = ‘a’; Arrays v Pointers (following are equivalent) void Foo(int arr[]) { } void Foo(int *arr) { } MyFooClass theFooObj; MyFooClass arrFoo[200]; //default constructors run MyFooClass *pFoo; pFoo = arrFoo; arrFoo[54] = theFooObj; pFoo = &theFooObj;

File IO In C:In C++:In Java: FILE *fp;ifstream inFile(“name.dat”);import java.io.*; FileInputStream infile = istream inFile;new FileInputStream( “name.dat” ); if ((fp = fopen( “name.dat”, “r” ))inFile.open(“name.dat”);ObjectInputStream input = != NULL {if ( inFile ) { // true of falsenew ObjectInputStream( infile ); fscanf( fp, “%d”, &i );inFile >> i;try { i = input.readInt( ); fclose(fp);inFile.close( );} catch ( EOFException e ) { }}input.close( ); } Note: for output, use ofstream.

example.h #ifndef EXAMPLE_H #define EXAMPLE_H Full.h file #endif

Dynamic Allocation 1. Pointer declarationint *p, *q; 2. Dynamic allocationp = new int; q = new int; 3. Deallocationdelete p; p = NULL; 4. Memory leakq = new int; ? ? ? p q p q p q p q ??? ? NULL Leak!

Dynamic Allocation Works with all Object types Bird *pBigBird pBigBird = Bird(“chicken”); string s = pBigBird->species;