Working With Command Line Arguements

This is a discussion on Working With Command Line Arguements within the C Programming forums, part of the General Programming Boards category; im looking for a good way of using command line arguements in a program. like app -x "some vaule". how ...

  1. #1
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    Exclamation Working With Command Line Arguements

    im looking for a good way of using command line arguements in a program. like app -x "some vaule". how do you guys do it? right now, im in if hell tying to get this right. is any other way?

    thanks

  2. #2
    moi
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    Code:
    int main (int argc, char *argv[])
    argv[0] is a null-terminated string of the name of your program (though what it actually contains can vary)
    argv[1] is a null-terminated string of the first argument the user passed to your program
    argv[2] is the second arg
    argv[argc-1] is the last arg that was passed
    hello, internet!

  3. #3
    End Of Line Hammer's Avatar
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    ..... and finally (to continue moi's help).... argv[argc] is a null pointer to provide a redundant check for the end of the list.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  4. #4
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    9
    Have you looked at getopt() ?

    something like:

    Code:
    #include <unistd.h>
    
    int main(int argc, char **argv) {
        int opt;
    
    
        while((opt = getopt(argc, argv, "p:V")) != -1) {
          switch(opt) { 
            case 'p':
              printf("argument p = %s\n", optarg);
              break;
            case 'V':
              verbose++;
              break;
            case ':'
              printf("Option %c needs a value\n", opt);
              break;
            case '?':
              printf("invalid option?\n");
              break;
          }
        }
    }

    getopt(3)
    Last edited by jabrams; 08-03-2002 at 04:29 PM.

  5. #5
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    Code:
    #include <stdio.h>
    
    void DefaultMessage ( void );
    
    int main ( int argc, char * argv[] )  
    {
    	if (argc == 2)
    	{
    		if(argv[1][0] == '?')
    		{
    			printf("Help stuff would go here.\n");
    		}
    		else
    		{
    			printf("%s \n", argv[1]);
    		}
    	}
    	else if ( argc >= 3 )
    	{
    		printf("Invalid input:\n");
    		printf("Only one command-line parameter allowed.\n");
    	}
    	else
    	{
    		DefaultMessage();
    	}
    	return 0;
    }
    
    void DefaultMessage ( void )
    {
    	printf("CmdLine.exe:\n");
    	printf("The purpose of this program is to demonstrate command line arguments.\n");
    	printf("This program will print whatever you type on the screen.\n\n");
    	printf("Example:\n");
    	printf("C:\\>CmdLine.exe Hmmm\n");
    	printf("Hmmm\n");
    }
    The world is waiting. I must leave you now.

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