C++ vector::resize()用法及代码示例

C++ vector::resize() 函数

vector::resize() 是 "vector" 头文件的库函数，用于调整向量的大小，它接受更新的元素数量和默认值(可选)并调整向量容器的大小。

注意：要使用矢量，请包括<vector>标题。

vector::resize() 函数的语法

    vector::resize();

参数： n- 是更新后的尺寸，val- 是分配给新大小的默认值，并且value_type()- 它是容器的值类型(第一个模板参数的类型的引用)。

返回值： void- 它什么都不返回。

例：

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

    Function call:
    cout << vector1.resize(10);

    Output:
    //if we print elements
    1 2 3 4 5 0 0 0 0 0

C++程序演示vector::resize()函数的例子

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

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

int main()
{
    vector<int> v1;

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

    //printing the elements
    cout << "vector elements are:";
    for (int x:v1)
        cout << x << " ";
    cout << endl;

    //resizing the size with default value
    //and printing the elements
    v1.resize(8, 99);

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

    //printing the elements
    cout << "vector elements are:";
    for (int x:v1)
        cout << x << " ";
    cout << endl;

    //resizing the size without default value
    //and printing the elements
    v1.resize(10);

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

    //printing the elements
    cout << "vector elements are:";
    for (int x:v1)
        cout << x << " ";
    cout << endl;

    return 0;
}

输出

Total number of elements:0
Total number of elements:5
vector elements are:10 20 30 40 50
Total number of elements:8
vector elements are:10 20 30 40 50 99 99 99
Total number of elements:10
vector elements are:10 20 30 40 50 99 99 99 0 0

参考：C++ vector::resize()