how to convert uppercase in cpp code example

Example 1: 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; 
}

Example 2: uppercase capitalise character in string c++

str[i] = toupper(str[i]);

Example 3: string to upper c++

std::string data = "This is a sample string.";
// convert string to upper case
std::for_each(data.begin(), data.end(), [](char & c){
c = ::toupper(c);
});