Why is there an error when I try to run this code using command line arguments in shell?

Question

I have a code called main.c that attempts to convert roman numerals into integers, and my code has to run via command line inputs, here is the code by the way:

and I would like to know what is the simplest way to solve this issue.

P.S. Yes, I know that the roman code that I provided is incomplete and doesn't cover many cases, I'll edit that, right now I just want to know why my code doesn't have an output

Answer 1

Your usage is wrong. The way you are calling your program feeds STDIN to the program that you never read.

You should use ./roman XVII