Processing arguments in C

args.c

char *s;
while (--argc > 0 && (*++argv)[0] == '-')
    for(s = argv[0]+1; *s != '\0'; s++)
        switch(*s) {
            case 'x':
                /* Set appropriate flags for 'x' option */
                break;
            case 'n':
                /* Set appropriate flags for 'n' option */
                break;
            default:
                printf("Illegal option %c\n", *s);
                argc = 0;
                break;
        }
if( argc != 1)
    printf("Usage: find -x -n pattern\n");
else
    /* Main program logic goes here */