Standard Template Library Programmer's Guide

queue<T, Sequence>

Categories: containers, adaptors

Component type: type

Description

A queue is an adaptor that provides a restricted subset of Container functionality A queue is a 'first in first out' (FIFO) data structure. [1] That is, elements are added to the back of the queue and may be removed from the front; Q.front() is the element that was added to the queue least recently. Queue does not allow iteration through its elements. [2]

Queue is a container adaptor, meaning that it is implemented on top of some underlying container type. By default that underlying type is deque, but a different type may be selected explicitly.

Example

int main() {
 queue<int> Q;
 Q.push(8);
 Q.push(7);
 Q.push(6);
 Q.push(2);
 assert(Q.size() == 4);
 assert(Q.back() == 2);
 assert(Q.front() == 8);
 Q.pop();
 assert(Q.front() == 7);
 Q.pop();
 assert(Q.front() == 6);
 Q.pop();
 assert(Q.front() == 2);
 Q.pop();
 assert(Q.empty());
}

Definition

Defined in the standard header queue, and in the nonstandard backward-compatibility header stack.h.

Template parameters

Parameter	Description	Default
T	The type of object stored in the queue.
Sequence	The type of the underlying container used to implement the queue.	deque<T>

Model of

Assignable, Default Constructible

Type requirements

• T is a model of Assignable.

• Sequence is a model of Front Insertion Sequence.

• Sequence is a model of Back Insertion Sequence.

• Sequence::value_type is the same type as T.

• If operator== is used, then T is a model of Equality Comparable

• If operator< is used, then T is a model of LessThan Comparable.

Public base classes

None.

Members

Member	Where defined	Description
value_type	queue	See below.
size_type	queue	See below.
queue()	Default Constructible	The default constructor. Creates an empty queue.
queue(const queue&)	Assignable	The copy constructor.
queue& operator=(const queue&)	Assignable	The assignment operator.