convert string to uppercase in c++ using by reference code example

Example: convert whole string to uppercase c++

#include<bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    string s = "Viet Nam"; 
    transform(s.begin(), s.end(), s.begin(), ::toupper);  //uppercase
    cout << s << endl; 
    return 0; 
}