std::deque::size

size_type size() const;

Returns the number of elements in the container, i.e. std::distance(begin(), end()).

Parameters

(none)

Return value

The number of elements in the container.

Exceptions

(none)	(until C++11)
`noexcept` specification: noexcept	(since C++11)

Complexity

Constant.

Example

The following code uses size to display the number of elements in a std::deque:

Run this code

#include <deque>
#include <iostream>
 
int main()
{ 
    std::deque<int> nums {1, 3, 5, 7};
 
    std::cout << "nums contains " << nums.size() << " elements.\n";
}

Output:

nums contains 4 elements.

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

array (C++11)
vector
deque
forward_list (C++11)
list
set
multiset
map
multimap
unordered_set (C++11)
unordered_multiset (C++11)
unordered_map (C++11)
unordered_multimap (C++11)
stack
queue
priority_queue

Member functions
deque::deque
deque::~deque
deque::operator=
deque::assign
deque::get_allocator
Element access
deque::front
deque::back
Iterators
deque::begindeque::cbegin (C++11)
deque::enddeque::cend (C++11)
deque::rbegindeque::crbegin (C++11)
deque::renddeque::crend (C++11)
Capacity
deque::empty
deque::size
deque::max_size
deque::shrink_to_fit
Modifiers
deque::clear
deque::insert
deque::emplace
deque::erase
deque::push_front
deque::emplace_front
deque::pop_front
deque::push_back
deque::emplace_back
deque::pop_back
deque::resize
deque::swap

empty	checks whether the container is empty (public member function)
max_size	returns the maximum possible number of elements (public member function)
resize	changes the number of elements stored (public member function)