stl vector 函數
C ++ vector :: at()函數 (C++ vector::at() function)
vector::at() is a library function of "vector" header, it is used to access an element from specified position, it accepts a position/index and returns the reference to the element at specified position/index.
vector :: at()是“ vector”頭文件的庫函數，用于從指定位置訪問元素，它接受位置/索引并返回對指定位置/索引處的元素的引用。
Note: To use vector, include <vector> header.
注意：要使用向量，請包含<vector>標頭。
Syntax of vector::at() function
vector :: at()函數的語法
vector::at(size_type n);
Parameter(s): void – It is a position of an element to be accessed.
參數： void –這是要訪問的元素的位置。
Return value: reference – It returns a reference to the element at position n.
返回值： reference –返回對位置n處元素的引用。
Example:
例：
Input:
vector<int> vector1{ 1, 2, 3, 4, 5 };
Function call:
cout << vector1.at(0) << endl;
cout << vector1.at(1) << endl;
Output:
1
2
C ++程序演示vector :: at()函數的示例 (C++ program to demonstrate example of vector::at() function)
//C++ STL program to demonstrate example of
//vector::at() function
#include <iostream>
#include <vector>
using namespace std;
int main()
{
vector<int> v1{ 10, 20, 30, 40, 50 };
//accessing elements
cout << "first element : " << v1.at(0) << endl;
cout << "second element: " << v1.at(1) << endl;
cout << "last element : " << v1.at(v1.size() - 1) << endl;
//accessing all elemenets
cout << "all elements of vector v1..." << endl;
for (int i = 0; i < v1.size(); i++)
cout << "element at index " << i << " : " << v1.at(i) << endl;
return 0;
}
Output
輸出量
first element : 10
second element: 20
last element : 50
all elements of vector v1...
element at index 0 : 10
element at index 1 : 20
element at index 2 : 30
element at index 3 : 40
element at index 4 : 50
Reference: C++ vector::at()
參考： C ++ vector :: at()
翻譯自: https://www.includehelp.com/stl/vector-at-function-with-example.aspx
stl vector 函數
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