C++ vector::resize()用法及代碼示例

C++ vector::resize() 函數

vector::resize() 是 "vector" 頭文件的庫函數，用於調整向量的大小，它接受更新的元素數量和默認值(可選)並調整向量容器的大小。

注意：要使用矢量，請包括<vector>標題。

vector::resize() 函數的語法

    vector::resize();

參數： n- 是更新後的尺寸，val- 是分配給新大小的默認值，並且value_type()- 它是容器的值類型(第一個模板參數的類型的引用)。

返回值： void- 它什麽都不返回。

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()函數的例子

//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;
}

輸出

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

參考：C++ vector::resize()