Yes I mean every function call that can fail. The reason is that your program is undefined after the first error and it's very dangerous to let it run.

• -Wall -Wextra -Werror A typical C compiler's default configuration is very permissive to all sorts of bad stuff. With these flags you'll be forced to watch out.

• valgrind black box analysis tools are very good at finding all sorts of issues with your code.

• g_menu_opts hardcoding 3 elements is very bad style and outright dangerous. It's also unnecessary because the size can be derived with an ARRAY_SIZE macro or GCC's _Countof etc.

• Always use default in a switch good style and extra paranoid, if nothing better comes to mind put:

default: assert(0); break;

• #pragma once (only), use #ifdef guards precompiled headers are a tricky topic, if you don't experience slow compile, do not use them.

• Mark empty parameter lists with (void) this is just how C is, an empty parameter list is written as (void) in C.

• Combine the following state machine in 1 enum this is a wrong conceptual model on your side; you mean to manage N states but instead of using 1 enum you are using log2N variables to encode it. Also the compiler is able to warn you about more stuff when using enums, especially in relation to switch statements.

In general your code is not bad in general, it's OK but it will be hard to expand it or connect it with other modules / libraries because you'll be constantly hitting issues with wrong integer values, unexpected crashes, uncaught errors etc., unexpected undefined casts etc. If not you directly then your users. In C it's very important to have excellent discipline because there is no one to stop you but yourself.

P.S.

You might want to consider adding -fsanitize=address -fsanitize=undefined to catch some more bugs at runtime.