Thread: Beginner to C, need help with command-line stuff..

  1. #1
    Registered User
    Join Date
    Oct 2005

    Beginner to C, need help with command-line stuff..

    So I've gotten kinda stuck. I'm trying to figure out this command-line arguments stuff.

    Basically if a user enters an integer x in the command line after the program name, how can I use this integer in my main() function? I can use the number they put in.

    Heres a lil sample of the code

    for ( i = 0; i < argv[1]; i++ )
    die1 = rollDie();
    resultArray2[total - 1]++;

    but it won't compile, saying I can't compare an integer (i) to a pointer (argv[1]). I've read 4 tutorials on command-line stuff and I haven't found anything that helps.

  2. #2
    Registered Luser cwr's Avatar
    Join Date
    Jul 2005
    Sydney, Australia
    argv[1] is a string. You need to convert it to an integer, look up the functions atoi and strtol.

  3. #3
    Registered User
    Join Date
    Aug 2005
    for ( i = 1; i < argc; ++i )
    argc contains the number of command-line arguments. So if you want to do something with each argument then create the loop as illustrated above. argc will always be at least 1 because the first argument is always the name of the program that is running.

    Now if you want to actually use the value that was typed on the commnd-line you will have to convert it to an integer. There are other conversion functions, but atoi() will be sufficient as long as you don't enter some ridiculously huge number on the command line.
    int x;
    for ( i = 1; i < argc; ++i )
       x = atoi(argv[i]);

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