command line arguments

This is a discussion on command line arguments within the C Programming forums, part of the General Programming Boards category; I have rethought variodic functions, is there anyway to mimic the Code: char *args[] /*main() parameter for command line arguments*/ ...

  1. #1
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    command line arguments

    I have rethought variodic functions, is there anyway to mimic the

    Code:
    char *args[] /*main() parameter for command line arguments*/
    but use integers, or my own type instead? pass a function several of my types and iterate through them as if they were in an array?

  2. #2
    Jack of many languages Dino's Avatar
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    You can't change the parm style that is used to pass parms to main(), unless you write your own command processor. With a typical operating system, in calling main(), it's always strings.

    If you write your own command processor, I suspect you could do anything you wanted to.
    Mac and Windows cross platform programmer. Ruby lover.

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  3. #3
    spurious conceit MK27's Avatar
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    Quote Originally Posted by tempster09 View Post
    I have rethought variodic functions, is there anyway to mimic the
    Of course. I kind of thought this is where you were at, I just didn't want to seem patronizing and say maybe you do not understand C that well yet?

    char *argv[] is a string literal array:
    Code:
    char *example[] = {"one", "two", "three"};
    You shouldn't alter this after declaration tho, so it's usefulness is somewhat limited.

    But consider a dynamic pointer array, char **example.
    Code:
    char **example = malloc(3*sizeof(char*));
    This can be resized. Each member is a pointer:
    Code:
    example[1] = malloc(32);
    Of course, if this were a struct or typedef array, you would just go:
    Code:
    example = malloc(3*sizeof(mystruct*));
    example[1] = malloc(sizeof(mystruct));
    So witness, you have a dynamic array of structs. This is the kind of thing you can put into initialization or allocation/deallocation functions. And:
    Code:
    void some_function(int len, mystruct **array);
    Guess what? If "len" is like argc -- that is, the number of pointers in "array", you now have an adaptable arrangement like argc, argv.

    Hope this is what you were looking for.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  4. #4
    ATH0 quzah's Avatar
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    Quote Originally Posted by MK27 View Post
    char *argv[] is a string literal array:
    Actually it's not. It's an array of pointers to characters. Which could, be if you wanted, an array of pointers to arrays of char:
    Code:
    #include<stdio.h>
    int main( void )
    {
        char foo[BUFSIZ] = "hello";
        char bar[BUFSIZ] = " ";
        char baz[BUFSIZ] = "world!\n";
        char *aop[3];
        size_t x = 0;
        
        aop[0] = foo;
        aop[1] = bar;
        aop[2] = baz;
        
        for( x = 0; x < 3; x++ )
            printf( "%s", aop[ x ] );
        
        return 0;
    }
    Quote Originally Posted by MK27 View Post
    You shouldn't alter this after declaration tho, so it's usefulness is somewhat limited.
    You can actually modify the arguments in arv. It's allowed by the standard.


    Quzah.
    Hope is the first step on the road to disappointment.

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