Is there some guides for designing error code in C

Question

It has confused me for a long time that is there a good way to design error code in C as the return code. I used to use magic number or global macro to define a specific error like using -1 as general failure. But when the project becomes large, I find it not easy to manage these error code. Can someone give me an example or a guide for how to design good error codes?

I used to consider that the error code may be split into some bit fields to specify the type of error or the function which throws the error or something else. I'm finding inspiration and there isn't a specific project for the error code. Maybe there are some good coded error codes in some famous projects that you know, please tell me the name of that project

I'll appreciate a lot.

Answer 1

You may like to use enum data types. for example:

typedef enum { KEY_NOT_FOUND, INVALID_DATA } errortype;

Answer 2

strerror provide user defined error codes.This implementation of strerror provides for user-defined extensibility. errno.h defines __ELASTERROR, which can be used as a base for user-defined error values.