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

From cppreference.net

C++
Containers library
std::stack
size_type size ( ) const ;

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

Contents

Parameters

(none)

Return value

The number of elements in the container adaptor.

Complexity

Constant.

Example

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

See also

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