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Command line argument

 
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Command line argument
eudos
post 2 Sep, 2006 - 10:59 AM
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Hi there.

I am tryin to use a program using comand line argument of my own... i mean like when i enter "./list -r" it should print in reverse order.. but i have proplem in the code below..
Can anyone plz help me with this.. smile.gif

CODE

// Print in reverse - initially false
    int reverse = 0;

        if((argc == 2 ) && (argv[1]  == -r)) {
             reverse = 1;
        }else {
             printf("Pls use : %s [-r]", argv[0]);
        }


    // Print list
    printf("The list contains:\n");
    if (reverse) {
       list = reverseList (list);
       printRecursive(list);
    } else {
       printRecursive(list);
    }
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Nova Dragoon
post 2 Sep, 2006 - 11:04 AM
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you need to do a string compare to find -r because, - and r are two letters which make a string
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Jayman
post 2 Sep, 2006 - 11:14 AM
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The problem is the argv[1] is a character array, you cannot make a literal comparision using the ==. So this statement (argv[1] == -r) will never work. You need to use the strcmp function to compare the the command argument with the expected value.

Function strcmp returns 0 if it matches and 1 if it does not. Here is a link that shows API for strcmp.

Should look like this:
CODE

if((argc == 2 ) && (strcmp(argv[1],"-r") == 0))
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eudos
post 2 Sep, 2006 - 11:20 AM
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Thanks.. code is now perfect. biggrin.gif
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skyhawk133
post 2 Sep, 2006 - 11:33 AM
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jayman and Nova, thanks for helping out eudos!

Eudos, I'm glad you got your code working, don't hesitate to come back to dream.in.code in the future if you have other questions.
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