C++ string.compare()

Question

I'm building a comparator for an assignment, and I'm pulling my hair out because this seems to simple, but I can't figure it out.

This function is giving me trouble:

int compare(Word *a, Word *b)
{
    string *aTerm = a->getString();
    string *bTerm = b->getString();

    return aTerm->compare(bTerm);
}

Word::getString returns a string*

Error:

 In member function `virtual int CompWordByAlpha::compare(Word*, Word*)':   
  no matching function for call to...

...followed by a bunch of function definitions.

Any help?

Answer 1

You're comparing a string to a string pointer, and that's not valid. You want

   return aTerm->compare(*bTerm);

Answer 2

You aren't getting the different uses of the * operator. The use of the * in "string* bTerm = b->getString()" means "bTerm is a pointer to a string". The use of the * inside of compare(*bTerm) means "take the value of the location pointed to by bTerm" instead of just using compare(bTerm) which simply attempts to compare the value of bTerm itself, which is a hex address.

This is also happening on the left side of that call:

aTerm->compare(*bTerm); //this statement
(*aTerm).compare(*bTerm); //is the same as this statement

The -> operator just reduces the amount of typing required.

P.S.: This kind of stuff you could have easily figured out from Google or your programming textbook. Although others may disagree, I don't feel that questions about completely basic syntax have any place on Stack Overflow.