C++ Vector at() Function

The C++ vector.at() returns a reference to an element within the vector.

Syntax:

Example, using a vector “v1” and position “p”.

v1.at(p);

Returns the value in the element at position p.

The following example uses a vector v1, and a position p to return a specific element.

int p = 3;
vector<int> v1 {11,12,13,14,15};
cout << v1.at(p);

Output: 14

This example is a complete program using vector at() function to print the contents of a vector. We are also using the vector size() function to determine the number of elements in the vector to iterate through.

#include<iostream>  
#include<vector>  

int main()  
{  
  std::vector<int> v1{1,2,3,4,5,6};

  for(int i=0;i<v1.size();i++)  
      std::cout<<v1.at(i) << " ";
        
  return 0;   
}  

Output: 1 2 3 4 5 6