passing functions as parameters?

This is a discussion on passing functions as parameters? within the C Programming forums, part of the General Programming Boards category; I'm new to C and am working on this project. In there, there's these lines of code... Code: static int ...

  1. #1
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    passing functions as parameters?

    I'm new to C and am working on this project. In there, there's these lines of code...

    Code:
    static int
    smpl_handler(manager man, void *virt_event, void *c_data, att_list attrs)
    {
        simple_rec_ptr loc_event = virt_event;
       printing stuff
    }
    then in main, they have this..

    Code:
    term_action(man, stn_ev, format_list, smpl_handler);
    term_action is a function and they're passing in the other function? smpl_handler has parameters but those aren't passed.. I'm confused as to what's going on here

    also smpl_handler is defined as "static int"... but it's a function that doesn't return any values....
    Last edited by dayalsoap; 08-27-2010 at 12:27 PM.

  2. #2
    C++ Witch laserlight's Avatar
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    A pointer to the smpl_handler function is passed such that smpl_handler can be invoked from term_action.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  3. #3
    Just a pushpin. bernt's Avatar
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    It's passing a pointer to the function. But because of the exact semantics of function-pointers in C this is often very confusing.

    If you really need more info you could check here here or read up with a C reference book (Kernighan does cover function pointers IIRC).

    EDIT: Beaten to the point. Again.
    Consider this post signed

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    Quote Originally Posted by bernt View Post
    It's passing a pointer to the function. But because of the exact semantics of function-pointers in C this is often very confusing.

    If you really need more info you could check here here or read up with a C reference book (Kernighan does cover function pointers IIRC).

    EDIT: Beaten to the point.
    Thanks for the reference! Looks good.

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    also, what about the "static int"? The function doesn't return any int...

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    Post the function code.
    Probably old K&R style code which does not have void type.

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    Quote Originally Posted by Bayint Naung View Post
    Post the function code.
    Probably old K&R style code which does not have void type.
    that is the code.. there is just one printf statement, that's it. I think you might be right in that it's older K&R style, as I don't see voids anywhere.

    Is K&R style more portable? This isn't that old of code.. circa 2007.

  8. #8
    a_capitalist_story
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    static preceding a function means the function is only visible within that file. More info here

  9. #9
    Third Eye Babkockdood's Avatar
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    Code:
    printing stuff
    What's up with this?

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