I suppose that you mean wrapping in curly-braces, for explicit syntax? if (cond) { return val; } Also, there is only one instance of ternary operator

I suppose that you mean wrapping in curly-braces, for explicit syntax? if (cond) { return val; } Also, there is only one instance of ternary operator in ANSI C: cond ? succ() : fail(); This ternary syntax does not appear in main.c "NULL_PTR" is a rather bold choice for an integer error status. I see where it’s coming from. It’s not wrong, but there are conventions for naming things. You should also be making use of stderr to output any error message or anything that is not your expected output. wc(1) is a Posix standard utility and you should have purchased the spec and keep one eye on the spec while implementing something like this. So far it is one cut above "Hello World". Unix exit value 0 should indicate success. Posix system calls always return 0 on success. ANSI C library calls as well. For user-defined functions, you don’t have access to the "errno" variable, so you do what you gotta do. Speaking of exit values, it’s also a good convention to explicitly use "exit()" rather than "return()" from main(). It’s exactly the same result. I recommend a book on standard C programming. I haven’t read a standards spec in 30 years.