Thestd::queue class template is acontainer adaptor that gives the functionality of aqueue - specifically, a FIFO (first-in, first-out) data structure.

The class template acts as a wrapper to the underlying container - only a specific set of functions is provided. The queue pushes the elements on the back of the underlying container and pops them from the front.

[edit]Template parameters

[edit]Member types

[edit]Member objects

[edit]Member functions

[edit]Non-member functions

[edit]Helper classes

[edit]Notes

[edit]Example

#include <cassert>#include <iostream>#include <queue> int main(){    std::queue<int> q;     q.push(0);// back pushes 0    q.push(1);// q = 0 1    q.push(2);// q = 0 1 2    q.push(3);// q = 0 1 2 3 assert(q.front()==0);assert(q.back()==3);assert(q.size()==4);     q.pop();// removes the front element, 0assert(q.size()==3); // Print and remove all elements. Note that std::queue does not// support begin()/end(), so a range-for-loop cannot be used.std::cout<<"q: ";for(;!q.empty(); q.pop())std::cout<< q.front()<<' ';std::cout<<'\n';assert(q.size()==0);}

q: 1 2 3

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

1. ↑Such as containers similar tostd::vector<bool> with additional support ofpop_front(). The resolution of this DR
   added support ofstd::vector<bool> forstd::stack andstd::priority_queue. The changes involvingstd::queue
   are for maintaining consistency.

[edit]See also

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