Parsing command-line arguments in C?

Question

I\'m trying to write a program that can compare two files line by line, word by word, or character by character in C. It has to be able to read in command line options

Answer 1

#include 

int main(int argc, char **argv)
{
    size_t i;
    size_t filename_i = -1;

    for (i = 0; i < argc; i++)
    {
        char const *option =  argv[i];
        if (option[0] == '-')
        {
            printf("I am a flagged option");
            switch (option[1])
            {
                case 'a':
                    /*someting*/
                    break;
                case 'b':
                    break;
                case '-':
                    /* "--" -- the next argument will be a file.*/
                    filename_i = i;
                    i = i + 1;
                    break;
                default:
                    printf("flag not recognised %s", option);
                    break;
            }
        }
        else
        {   
            printf("I am a positional argument");
        }

        /* At this point, if -- was specified, then filename_i contains the index
         into argv that contains the filename. If -- was not specified, then filename_i will be -1*/
     }
  return 0;
}