c ++ assign函数

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

vector::assign() is a library function of "vector" header, it is used to initialize a vector or assign content to a vector, it assigns the new content to the vector, update the existing content, and also resizes the vector's size according to the content.

vector :: assign()是“ vector”标头的库函数，用于初始化矢量或将内容分配给矢量，将新内容分配给矢量，更新现有内容，并调整矢量的大小根据内容。

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

注意：要使用向量，请包含<vector>标头。

Syntax of vector::assign() function

vector :: assign()函数的语法

vector::assign(iterator_first, iterator_last);    vector::assign(size_type n, value_type value);

Parameter(s):

参数：

In case of type 1: iterator_first, iterator_last – are the first and last iterators of a sequence with them we are going to assign the vector.

In case of type 2: n – is the size of the vector and value – is a constant value to be assigned.

在类型1的情况下， iterator_first和iterator_last –是序列的第一个和最后一个迭代器，我们将为其分配向量。

对于类型2： n –是向量的大小，而value –是要分配的常数。

Return value: void – In both of the cases it returns nothing.

返回值： void –在两种情况下均不返回任何内容。

Example:

例：

Input:    vector
    
      v1;    vector
     
       v2;        //assigning    v1.assign(5, 100);    v2.assign(v1.begin(), v1.end());    Output:    //if we print the value    v1: 100 100 100 100 100    v2: 100 100 100 100 100
     
    

C ++程序演示vector :: assign()函数的示例 (C++ program to demonstrate example of vector::assign() function)

//C++ STL program to demonstrate example of//vector::assign() function#include 
    
     #include 
     
      using namespace std;int main(){
       //declaring vectors    vector
      
        v1;    vector
       
         v2;    vector
        
          v3;    //an array that will be used to assign a vector    int arr[] = {
    10, 20, 30, 40, 50 };    //assigning vectors    //assigning v1 with 5 elements and 100 as default value    v1.assign(5, 100);    //assigning v1 with array    v2.assign(arr + 0, arr + 5);    //assigning v3 with vector v2    v3.assign(v2.begin(), v2.end());    //pritning the vectors    cout << "v1: ";    for (int x : v1)        cout << x << " ";    cout << endl;    cout << "v2: ";    for (int x : v2)        cout << x << " ";    cout << endl;    cout << "v3: ";    for (int x : v3)        cout << x << " ";    cout << endl;    return 0;}
        
       
      
     
    

Output

输出量

v1: 100 100 100 100 100v2: 10 20 30 40 50v3: 10 20 30 40 50

Reference:

参考：

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c ++ assign函数