Cant Understand the syntax

This is a discussion on Cant Understand the syntax within the C Programming forums, part of the General Programming Boards category; I've seen the following in a .c File Code: static void MDString PROTO_LIST ((char *)); static void MDTimeTrial PROTO_LIST ((void)); ...

  1. #1
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    Cant Understand the syntax

    I've seen the following in a .c File
    Code:
    static void MDString PROTO_LIST ((char *));
    static void MDTimeTrial PROTO_LIST ((void));
    static void MDTestSuite PROTO_LIST ((void));
    static void MDFile PROTO_LIST ((char *));
    static void MDFilter PROTO_LIST ((void));
    static void MDPrint PROTO_LIST ((unsigned char [16]));
    But cant understand what does it mean.
    PROTO_LIST is a function or a struct name.
    But still the syntax is complex to me I cant understand it.
    anyone plese clearify.

  2. #2
    cas
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    Back in the bad old days, C didn't have prototypes, so function declarations looked like:
    Code:
    char *f();
    instead of
    Code:
    char *f(const char *);
    Or whatever the parameters were. The point is that K&R C (the older dialect) had no way of listing the types of parameters to a function. As you are probably aware, having the types is extremely useful. So people wanted to use prototypes, but also needed to be compatible with older compilers.

    Thus you get a macro like PROTO_LIST. Its definition probably looks something like:
    Code:
    #if __STDC__
    #define PROTO_LIST(p) p
    #else
    #define PROTO_LIST(p) ()
    #endif
    So if __STDC__ is true (that is, we're on a standards-compliant implementation), the prototype is used. If it's false, no prototype is used. Compatible with both ancient and modern compilers.

  3. #3
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    Haaaaaaaaa I got a Brand knew drop of historical Knowledge.
    C didn't have prototypes
    Then how did programmers pass the arguments ?

  4. #4
    Deathray Engineer MacGyver's Avatar
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    You just passed them. We're talking prototypes, not types.

  5. #5
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    I meant if Its char *f();
    then how can one pass argument to f() ?

  6. #6
    and the hat of wrongness Salem's Avatar
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    You could pass anything you liked (which was part of the problem, and why tools like lint existed).

    f(123);
    f("hello world");
    would silently compile on very old compilers.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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    so how the function body get that argument.
    e.g. now a days we do f(int x)
    so if f(123) is used x = 123 but if its f() then who will hold that 123 ??

  8. #8
    Deathray Engineer MacGyver's Avatar
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    You would define a function in some manner like this:

    Code:
    int dosomething(x)
    int x;
    {
        printf("x = %d\n", x);
    }

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