Passing Through A Variable Argument List

This is a discussion on Passing Through A Variable Argument List within the C Programming forums, part of the General Programming Boards category; Hello, I'm just trying to define a small API for this wickedy thing I'm doing. While some functions are complex, ...

  1. #1
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    Question Passing Through A Variable Argument List

    Hello,

    I'm just trying to define a small API for this wickedy thing I'm doing. While some functions are complex, others merely wrap certain C runtime functions.

    Right now I'm trying to define a function that wraps sscanf. As this function uses a variable argument list, assuming I declare the wrapper with the same arguments how do I pass it a va_arg?
    Code:
    int String_Scan(char *buffer, char *format, ...)
    {
       // ?
       // Profit
    }

  2. #2
    Lean Mean Coding Machine KONI's Avatar
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    You might want to have a look at this thread, especially post #4.

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    I don't think I could use a for loop and make individual calls to sscanf because I would also have to look through the format string and make sure it points to the nearest specifier. Seems to over-complicate things somewhat.

  4. #4
    ATH0 quzah's Avatar
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    I think you have to. You can just pass over "...". I think you have to do the conversion yourself.


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    I suppose rather than fluffing around I could just use:-
    Code:
    #define String_Scan   sscanf

  6. #6
    and the hat of wrongness Salem's Avatar
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    Well if String_Scan ultimately calls sscanf, then you need to use the va_arg stuff and pass the "..." onto vsscanf()

    In fact, it's generally a lot easier all round if you begin by providing vString_Scan() where the ... is replaced by a va_arg parameter, then String_Scan() is just a very thin wrapper around vString_Scan() which does all the work (and calls vsscanf).
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    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by SMurf View Post
    Right now I'm trying to define a function that wraps sscanf. As this function uses a variable argument list, assuming I declare the wrapper with the same arguments how do I pass it a va_arg?
    vsscanf() is meant for this.

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