using getopt to parse command line arguments

Question

I'm trying to use getopt to parse my command line arguments but i'm having an issue where it is setting the wrong values its skipping case 1 and setting case 2 as case 1.Here is the while loop of just the cases. The flags work fine its just reading in by position that is the problem.

while ((c = getopt (argc, argv, "-l:u:eo")) != -1)
         switch (c)
           {
           case 1:
            printf("here\n");
             lower = atoi(optarg);
             break;
           case 2:
             upper = atoi(optarg);
             break;
    }

here is the output from the terminal after running the program.

(%) fibon 12 22
here
here
lower = 22, upper = 0, even = 0, odd = 0
Usage: fibon[[lower upper] | [-l lower -u upper]] [-e|-o]

Some programmer dude · Accepted Answer · 2015-01-25 19:56:31Z

1

From the getopt(3) manual page:

If the first character of optstring is '-', then each nonoption argv-element is handled as if it were the argument of an option with character code 1.

That means that both numbers will be returned from getopt as 1. You need to keep track of which option you have yourself.

answered Jan 25, 2015 at 19:56

Some programmer dude

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3 Comments

Zypher Over a year ago

can you clarify more i don't understand how to keep track of the options

Some programmer dude Over a year ago

@user3400512 Keep a counter, initialized to 1. If it's 1 its the first value and you increase the counter. If it's 2 it's the second value. Etc.

Zypher Over a year ago

i tried doing the counter and when counter is 1 lower = atoi(argv[1]) and increment the counter and do the same for when counter is 2 but it still isn't working.

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