OK, I think I’ve got this figured out!

I already declared “using namespace std;” in my main.cpp file, but in the .h, I did not, so technically I was supposed to be calling std::string. What a stupid mistake!

It’s usually best to limit your use of ‘using namespace’, because in a large program you can easily get naming conflicts that way. In general, the more limited your “name lifting” is, the more flexible and reusable your code will be.

I recommend that you declare myClass as taking std::string. Then, if you want the abbreviated form for convenience within the class, make a member type declaration at the top of the class, e.g.

class myClass {
typedef std::string string;
myClass( string s );

.. The other wrinkle here has to do with performance. It’s better to pass a ‘const string & ) to these functions than an actual string value: this allows the compiler to eliminate the overhead of making a private copy of the string for the function, which is often unnecessary and wasteful:

bool myFunction(const string & guessWord);