Read the error message, it's pretty clear.
I have no idea which compiler you are using, so I threw your code into
Online GDB[
^] and it came back with this:
main.c: In function ‘main’:
main.c:84:48: error: ‘result_count’ undeclared (first use in this function); did you mean ‘resultcount’?
84 | int* result = compareTriplets(3, a, 3, b, &result_count);
| ^~~~~~~~~~~~
| resultcount
main.c:84:48: note: each undeclared identifier is reported only once for each function it appears in
So, the error is in file "main.c", on line 84, column 48, and it points at teh variable name
result_count
and says
"‘result_count’ undeclared (first use in this function); did you mean ‘resultcount’?"
That's pretty explicit, it even suggests the variable name you probably meant to use!
And looking at the line above, it's probably very, very right:
int resultcount;
So ... change the declaration to match the useage:
int result_count;
And the error goes away.
You should expect to get syntax errors every day, probably many times a day while you are coding - we all do regardless of how much experience we have! Sometimes, we misspell a variable, or a keyword; sometimes we forget to close a string or a code block. Sometimes the cat walks over your keyboard and types something really weird. Sometimes we just forget how many parameters a method call needs.
We all make mistakes.
And because we all do it, we all have to fix syntax errors - and it's a lot quicker to learn how and fix them yourself than to wait for someone else to fix them for you! So invest a little time in learning how to read error messages, and how to interpret your code as written in the light of what the compiler is telling you is wrong - it really is trying to be helpful!
So read this:
How to Write Code to Solve a Problem, A Beginner's Guide Part 2: Syntax Errors[
^] - it should help you next time you get a compilation error!