1. Copyright © 2004 - 2016 – Curt Hill
STL List
Details
Copyright © – Curt Hill

2. Copyright © 2004 - 2016 – Curt Hill
Forward
This will have something in common with the vector
It is another container class
The design of the STL is to keep things similar
All STL container classes are black boxes
We do not need to know how it is organized to use
We do need to understand the implementation to evaluate the tradeoffs
Internally list is a doubly linked list
This allows our iterators to go forward or backward
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3. Copyright © 2004 - 2016 – Curt Hill
List Library
Like a vector either <List.h> or <list> works
If you use <list>
You must also use using namespace std;
This is preferred for recent versions of our IDE
Copyright © – Curt Hill

4. Copyright © 2004 - 2016 – Curt Hill
Constructors
Default: list<type> lt;
This form requires a default constructor for type
All primitives have a null constructor
The default parameter is a alternative memory manager
The sized one exists: list<type> ls(int N);
Not needed, since list is not contiguous storage
Makes it easy to convert one container class to another
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5. Copyright © 2004 - 2016 – Curt Hill
Copy Constructors
Copy: list<type> lc(container)
The container is another STL list of same type
Partial copy: list <type> vc(It1,It2)
It1 and It2 are input iterators in an existing container class
Recall that iterators are specialized pointers into a STL container class
Does not have to be a list, but sequentiality has to exist
This constructor then copies from It1 to It2 into a new list
It1 better be before It2
This could be the entire container
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6. Copyright © 2004 - 2016 – Curt Hill
Operators
Assignment
May use the = operator
Erases the entire list and copies in the new one
assign(It1,It2)
Similar to partial copy constructor
Reference
The subscripting brackets may not be used with lists nor can the at function
All such references need an iterator
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7. Copyright © 2004 - 2016 – Curt Hill
Deep or Shallow Copy?
Two terms pertaining to the copy of a pointer based structure
A shallow copy only copies a pointer
A deep copy copies the things referred to by the pointer and makes a new pointer
What does STL do with assignments or partial copies?
Deep and shallow
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8. Copyright © 2004 - 2016 – Curt Hill
STL Copies
What happens when one container is assigned to another or a partial copy constructor is executed?
STL does a deep copy of all that it knows about
It will use the copy constructor (or assignment operator) for each contained item
If the copy constructor does a deep copy of the contained class then a deep copy occurs
Otherwise a mixture of deep and shallow
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9. Copyright © 2004 - 2016 – Curt Hill
Iterators
List iterators are similar to other container classes
Iterator presentation
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10. Other member functions
void clear()
Deletes all elements
int size()
Returns the number of elements
int capacity() is not supported
capacity() – size() is used in a vector to determine how many may be added without copying
int max_size()
Maximum capacity
This is a function of available memory
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11. Copyright © 2004 - 2016 – Curt Hill
More member functions
void push_back(TYPE)
Inserts a new item at end
void pop_back()
Deletes the last item
void push_front(TYPE)
Inserts a new item at front end
This (and next) was not available on vector
void pop_front()
Deletes the first item
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12. Insertion and deletion
iterator insert(iterator N, TYPE t)
Insert value t before position N
Returned iterator points at the new t
In a vector this is hard, everything must be slid down
In a list it is just pointer manipulation
There are several other inserts as well
iterator erase(interator M, iterator N)
Deletes a range of elements from M to before N
iterator erase(interator M)
Delete the first one on the list that matches
void remove(const TYPE &)
Delete all that match based on comparisons
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13. Copyright © 2004 - 2016 – Curt Hill
Comparisons
Lists have the following operators overloaded:
==, !=, <, >, >=, <=
These force an element by element comparison
The < is true if every element is less than corresponding element in other
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14. Copyright © 2004 - 2016 – Curt Hill
Other methods
front()
Returns reference to first element
Same as end() if list is empty
back
Returns reference to last element
swap (list<TYPE>)
Swaps two lists of same type
empty
Returns size == 0
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15. Copyright © 2004 - 2016 – Curt Hill
List algorithms
None of these are present in vector
void reverse()
Reverses the direction of a linked list
void sort()
Sorts the list
Uses entire data as key
void unique()
Eliminates consecutive duplicate entries from the list, leaving only the first
If the list is unordered there may be duplicates
void splice(iterator position, list<T> first, list <T> last)
Inserts into the list before position the sub-list starting at first and ending at last
The default for last is the end of the list
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16. Copyright © 2004 - 2016 – Curt Hill
New Include
If you use:
sort, unique, splice, find, reverse
You will need: #include <algorithm>
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