changing character to uppercase c++ code example

Example 1: c++ char to uppercase

char choice; 
// it will instantly transform it to upper case without the need
// to convert it to int first
choice = (char)toupper(choice);

Example 2: 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; 
}