HELLO!!!!!, I am a little confused about when to use a specific preprocessor directive. I know that each directive contains different reserved words and library identifiers, but how do you know when to use them? Since I don't know much about this, I have been sticking to <iostream> and <iomanip>, but I don't even know what they mean. Choosing a directive is like a guess and check game with me. PLEASE HELP. Thanks.