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Difference between revisions of "cpp/container/vector/size"

From cppreference.com
< cpp‎ | container‎ | vector
m (langlinks)
 
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#include <vector>
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{{include page|cpp/container/size|vector}}
#include <iostream>
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{{langlinks|de|es|fr|it|ja|pl|pt|ru|zh}}
int main()
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{  
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    std::vector<int> nums {1, 3, 5, 7};
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    std::cout << "nums contains " << nums.size() << " elements.\n";
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}
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Latest revision as of 07:08, 7 November 2021

 
 
 
 
size_type size() const;
(noexcept since C++11)
(constexpr since C++20)

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

Contents

[edit] Parameters

(none)

[edit] Return value

The number of elements in the container.

[edit] Complexity

Constant.

[edit] Example

The following code uses size to display the number of elements in a std::vector<int>:

#include <cassert>
#include <vector>
 
int main()
{
    std::vector<int> nums;
    assert(nums.size() == 0);
    nums = {1, 2, 3, 4};
    assert(nums.size() == 4);
}

[edit] See also

returns the number of elements that can be held in currently allocated storage
(public member function) [edit]
checks whether the container is empty
(public member function) [edit]
returns the maximum possible number of elements
(public member function) [edit]
changes the number of elements stored
(public member function) [edit]
(C++17)(C++20)
returns the size of a container or array
(function template) [edit]