C++ - extending a data type

Question

Is there a way to extend a data type in C++, like you can in JavaScript?

I would imagine this is kind of like this:

char data[]="hello there";
char& capitalize(char&)
{
    //Capitalize the first letter. I know that there
    //is another way such as a for loop and subtract
    //whatever to change the keycode but I specifically 
    //don't want to do it that way. I want there
    //to be a method like appearance.
}

printf("%s", data.capitalize());

This should somehow print.

Answer 1

The closest you can get is using operator overloading, e.g.

#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>

std::string operator!(const std::string& in) {
  std::string out = in;
  std::transform(out.begin(), out.end(), out.begin(), (int (*)(int)) std::toupper);
  return out;
}

int main() {
  std::string str = "hello";
  std::cout << !str << std::endl;
  return 0;
}

Alternative approaches include creating a class with operator std::string overloaded and a constructor to initialize it using an std::string.