Chapter 16Standard Template Library Containers and Iterators

Range-based for loops

The range-based for loop is a for loop that iterates through each element in a vector or container.

A range-based for loop is also known as a for each loop. The range-based loop declares a new variable that will be assigned with each successive element of a container, such as a vector, from the first element to the last element.

example: rangeLoop.cpp

Range-based for loops

Range Based for loops provide several advantages to normal for loops:

1. Improved Readability - decreases the amount of code you have to write to setup a for loop.

2. Reduced Errors - range-based loops prevent you from incorrectly accessing elements outside the containers range.

3. Clearer Intentions - range-based loops make it more clear what the programmer is intending.

example: rangeLoop.cpp

Modifying Elements

When modifying elements inside a range-based for loop, remember to include &.

example: rangeModification.cpp

for (int &value : myVector) { value = 10; }

List Container

The list container is an STL container that contains a sequence of elements.

#include <list>

The list container is implemented as a templated class

The list implementation is that of a doubly linked list.

Common List functions:

See ZyBook Chapter 16.2

example: list.cpp

List IteratorAn iterator is an object that points to a location in a list and can be used to traverse the list bidirectionally.

Inserting and removing elements using iterators:

myList.begin() // returns iterator at beginning of list

myList.end() // returns iterator at end of list

Pair

The pair class is an STL container that consists of two elements

#include <utility>

The pair container is implemented as a templated class

Many STL container classes make use of the pair container. Ex: key-value pairs in maps.

example: pair.cpp

pair<string, int> myPair;

Map

The map class is an STL container that utilizes the pair container to store elements as key-value pairs

#include <map>

The map container is implemented as a templated class

where K is the key data-type and V is the value data type.

example: map.cpp

map<K, V> newMap; 

Map

example: map.cpp

Set

The set class is an STL container that defines a collection of unique elements.

#include <set>

The set container is implemented as a templated class

Sets are often used when a programmer does not want duplicate elements in a collection as it has built in duplication error handling.

example: set.cpp

set<T> newSet; 

Set

example: setOperations.cpp

Queue

The queue class is an STL container that contains elements and support inserting from the tail and retrieval from the head.

#include <queue>

The queue container is implemented as a templated class

The Queue class is a FIFO data structure.

example: queue.cpp

queue<T> newQueue; 

Queue

example: queue.cpp

Deque

The deque (“deck”) class is an STL container that contains elements and support inserting and removal at both the tail and the head.

#include <deque>

The queue container is implemented as a templated class

We can use specific deque functions to make it act as a stack. A Deque can either be a FIFO or LIFO data structure depending on how you use it

example: deque.cpp

deque<T> newDeque; 

Deque

find()

The find() function seeks a specific value in a range of elements. It can be used with a number of STL containers such as lists and vectors.

#include <algorithm>

The container elements can be any C++ data type that supports the equality operator (==).

find() returns an iterator to the first element in the range that is equal to value. If value is not found, find() returns iteratorLast.

example: find.cppfindObject.cpp

find(iteratorFirst, iteratorSecond, value)

find_if()

The find_if() function is a variation of the find() function, defined in the STL algorithms library, that searches a range for an element that satisfies a boolean condition via a boolean function

#include <algorithm>

Each element inside the container is passed to the function individually.

find_if() returns an iterator to the first element in the range that is equal to value. If value is not found, find_if() returns iteratorLast.

example: findif.cpp

find_if(iteratorFirst, iteratorSecond, func)

sort()

The sort() function arranges a container's elements in ascending order. Can be performed on numerous STL containers like vectors and lists.

#include <algorithm>

The sorting algorithm function takes in 2 iterators as parameters, usually the first and last iterator in a collection container.

example: sort.cpp

sort(iteratorFirst, iteratorSecond)

random_shuffle()

The random_shuffle() function randomizes the order of a container by using iterators. Can be performed on numerous STL containers like vectors and lists.

#include <algorithm>

The random_shuffle algorithm function takes in 2 iterators as parameters, usually the first and last iterator in a collection container.

example: random_shuffle.cpp

random_shuffle(iteratorFirst, iteratorSecond)