C++ vector::capacity()用法及代码示例

C++ vector::capacity() 函数

vector::capacity()是"vector"头的库函数，用于求向量的容量，返回当前分配给向量的存储空间。

注意：要使用矢量，请包括<vector>标题。

vector::capacity() 函数的语法

    vector::capacity();

参数： void– 它不接受任何参数。

返回值： size_type– 它返回容量，即向量的存储空间。

例：

    Input:
    vector<int> vector1{ 1, 2, 3, 4, 5 };

    Function call:
    cout << vector1.capacity();

    Output:
    8

C++程序演示vector::capacity()函数的例子

//C++ STL program to demonstrate example of
//vector::capacity() function

#include <iostream>
#include <vector>
using namespace std;

int main()
{
    vector<int> v1;

    //printing the size & capacity of the vector
    cout << "Total number of elements:" << v1.size() << endl;
    cout << "Storage space:" << v1.capacity() << endl;

    //pushing elements
    v1.push_back(10);
    v1.push_back(20);
    v1.push_back(30);
    v1.push_back(40);
    v1.push_back(50);

    //printing the size & capacity of the vector
    cout << "Total number of elements:" << v1.size() << endl;
    cout << "Storage space:" << v1.capacity() << endl;

    return 0;
}

输出

Total number of elements:0
Storage space:0
Total number of elements:5
Storage space:8

参考：C++ vector::capacity()