See how parts of the code were swallowed in the line if (a return -1;? That's one of the reasons why Avanta told you to format your code.

Just put small code snippets between single backticks (`some fragment`) and multi-line snippets between lines of three backticks:

```

lines
of
code

```

C is fine. Don't mark an issue if it is a problem with your code.
Format your code with markdown if you want someone to help you.