It doesn't even make sense to use strchr for determining the position of 'r', when the code checks that the position of '-' is at index 0.

Your solution is perfectly fine. Even if you don't have access to strchr for some reason, the original snippet is really convoluted.

You could just write (strlen(argv[1]) > 1 && argv[1][0] == '-' && argv[1][0] == 'r') if you really want to.

It could make some sense to use strchr, because in idiomatic UNIX tools, single character command line options can be clustered. But that also means that subsequent code should not be tested for a specific position.

And if you ever find yourself actually doing command line parsing, use getopt(). It handles all the corner cases reliably, and consistent with other tools.

Of course, `&&` in C is short-circuiting so it's safe without the `strlen()` too, as long as the argument is there i.e. not NULL.

Also, the use of a convoluted `if` to conditionally assign a literal boolean is a code smell (to me), I would drop the `if` and just use:

    in_reverse = argc > 0 && argv[1][0] == '-' && argv[1][1] == 'r';

Your code actually has 2 bugs. The first I assume is just a typo and you meant to use [1][1] == ‘r’. The second one is that you would accept “-rblah” as well.