usage of extern keyword

This is a discussion on usage of extern keyword within the C++ Programming forums, part of the General Programming Boards category; can some pro quickly explain what's the use of extern keyword? sometimes i see a function declared as: extern int ...

  1. #1
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    Unhappy usage of extern keyword

    can some pro quickly explain what's the use of extern keyword?

    sometimes i see a function declared as:
    extern int myFunc();

    what does the extern do there?

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    Just Lurking Dave_Sinkula's Avatar
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    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by ilikepure View Post
    can some pro quickly explain what's the use of extern keyword?

    sometimes i see a function declared as:
    extern int myFunc();

    what does the extern do there?
    It is redundant and not necessary (for function prototypes, as in your case).

    The only reason you would be using extern is if you were using global variables across modules. And global variables, as most people agree, are a bad thing, so if you see the word "extern" you should probably be thinking "bad code," or at least code that could be improved.

    EDIT: Of course, there is the extern "C" thing, but that's just the extern keyword hacked into a new role. If you aren't calling C code from C++ code, there is no need for it.

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