Operator overloading (thing)

One interesting part of operator overloading that has not been mentioned above is the ability to overload the "conversion operators". You can override the conversion operators to allow your user-defined types to be converted to either built-in types or other user-defined types.

A member function Class::operator X(), where X is a type name, defines behaviour for a conversion of Class to X. Note that lack of return value - the type is mentioned as part of the function name, and cannot be repeated as the return type. Leave the return type blank.

Consider a String class -

class String {
  private:
    char* data;
  public:
    operator char*();

    ...
};

String::operator char*() {
  return data;
}

int main() {
  String s = "foobar";
  char* c = s; // allows implicit conversion
}

Use this technique sparingly, ambiguities with user-defined and built-in operators are likely to be quite common.