CPP/Strings/Case Conversion

#include <string>
#include <algorithm>    // transform
#include <functional>   // ptr_fun
#include <cctype>       // toupper, tolower
#include <iostream>
 
int main()
{
    std::string clive = "Clive Cherishes Capitals",
                lewis = "Lewis LOVES Lowercase";
 
    // transform each character in 'clive' with 'toupper'
    std::transform(clive.begin(), clive.end(), clive.begin(),
                   std::ptr_fun<int,int>(std::toupper) );
 
    // transform each character in 'lewis' with 'tolower'
    std::transform(lewis.begin(), lewis.end(), lewis.begin(),
                   std::ptr_fun<int,int>(std::tolower) );
 
    std::cout << clive << std::endl;
    std::cout << lewis << std::endl;
}