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std::vector<T,Allocator>:: capacity

From cppreference.net

C++
Containers library
std::vector
Member types
Member functions
Non-member functions
(until C++20) (until C++20) (until C++20) (until C++20) (until C++20)
Deduction guides (C++17)
size_type capacity ( ) const ;
(noexcept since C++11)
(constexpr since C++20)

컨테이너가 현재 공간을 할당받은 요소들의 개수를 반환합니다.

목차

매개변수

(없음)

반환값

현재 할당된 저장 공간의 용량.

복잡도

상수.

예제

이 코드 실행 
#include <iomanip>
#include <iostream>
#include <vector>
int main()
{
    int sz = 100;
    std::vector<int> v;
    auto cap = v.capacity();
    std::cout << "Initial size: " << v.size() << ", capacity: " << cap << '\n';
    std::cout << "\nDemonstrate the capacity's growth policy."
                 "\nSize:  Capacity:  Ratio:\n" << std::left;
    while (sz-- > 0)
    {
        v.push_back(sz);
        if (cap != v.capacity())
        {
            std::cout << std::setw( 7) << v.size()
                      << std::setw(11) << v.capacity()
                      << std::setw(10) << v.capacity() / static_cast<float>(cap) << '\n';
            cap = v.capacity();
        }
    }
    std::cout << "\nFinal size: " << v.size() << ", capacity: " << v.capacity() << '\n';
}

가능한 출력: 

Initial size: 0, capacity: 0
Demonstrate the capacity's growth policy.
Size:  Capacity:  Ratio:
1      1          inf
2      2          2
3      4          2
5      8          2
9      16         2
17     32         2
33     64         2
65     128        2
Final size: 100, capacity: 128

참고 항목

요소의 개수를 반환합니다
(public member function)
저장 공간을 예약합니다
(public member function)