stl resize函数_vector :: resize（）函数以及C ++ STL中的示例

stl resize函数

C ++ vector :: resize()函数 (C++ vector::resize() function)

vector::resize() is a library function of "vector" header, it is used to resize the vector, it accepts the updated number of elements and a default value (optional) and resizes the vector container.

vector :: resize()是“ vector”标头的库函数，用于调整矢量的大小，它接受更新的元素数量和默认值(可选)，并调整矢量容器的大小。

Note: To use vector, include <vector> header.

注意：要使用向量，请包含<vector>标头。

Syntax of vector::resize() function

vector :: resize()函数的语法

    vector::resize();

Parameter(s): n – is the updated size, val – is the default value to be assigned to the new size, and value_type() – it is the value type of the container (a reference of the type of the first template parameter).

参数： n-是更新的大小， val-是要分配给新大小的默认值， value_type() -它是容器的值类型(第一个模板参数类型的引用) )。

Return value: void – It returns nothing.

返回值： void –不返回任何内容。

Example:

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()函数的示例 (C++ program to demonstrate example of vector::resize() function)

//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;
}

Output

输出量

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

Reference: C++ vector::resize()

参考： C ++ vector :: resize()