std::queue<T,Container>::size

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (哋它亢++11)

vector

vector<bool>

deque

forward_list (哋它亢++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (哋它亢++11)

unordered_multiset (哋它亢++11)

unordered_map (哋它亢++11)

unordered_multimap (哋它亢++11)

Adaptors

stack

queue

priority_queue

flat_set (哋它亢++23)

flat_multiset (哋它亢++23)

flat_map (哋它亢++23)

flat_multimap (哋它亢++23)

Views

span (哋它亢++20)

mdspan (哋它亢++23)

Iterator invalidation

Member function table

Non-member function table

 

std::queue

Member functions

queue::queue

queue::~queue

queue::operator=

Element access

queue::front

queue::back

Capacity

queue::empty

queue::size

Modifiers

queue::push

queue::push_range (哋它亢++23)

queue::emplace (哋它亢++11)

queue::pop

queue::swap (哋它亢++11)

Non-member functions

swap(std::queue) (哋它亢++11)

operator==operator!=operator<operator>operator<=operator>=operator<=> (哋它亢++20)

Helper classes

uses_allocator<std::queue> (哋它亢++11)

formatter<std::queue> (哋它亢++23)

Deduction guides(哋它亢++17)

 

size_type size() const;

Returns the number of elements in the container adaptor. Equivalent to return c.size().

Parameters

(none)

Return value

The number of elements in the container adaptor.

Complexity

Constant.

Example

Run this code

#include <algorithm>
#include <cassert>
#include <queue>
 
int main()
{
    std::queue<int> queue;
 
    assert(queue.size() == 0);
 
    const int count = 8;
 
    for (int i = 0; i != count; ++i)
        queue.push(i);
 
    assert(queue.size() == count);
}

See also

empty	checks whether the container adaptor is empty (public member function)
sizessize (哋它亢++17)(哋它亢++20)	returns the size of a container or array (function template)