Looking for Feedback on My C Code Style

Your use of camelCase for variables and snake_case for function names looks solid. However, some variable names could be clarified. For instance, instead of `luckyNum`, which sounds like a single number, consider `luckyNums` or `luckyNumList` since it represents a collection. It’s also more common to place the `_MAX` part of a constant name at the end, so renaming `LUCKY_MAX_NUM` to something like `LUCKY_NUM_MAX` would be more conventional. For variable `swapNum`, think of using `tempNum` instead, since it represents a temporary value for swapping. You might also want to limit the scope of temporary variables to make them easier to understand. Let the names reveal their purpose clearly!

How did you learn C to code like this? Any resources you’d recommend?

I noticed that the argument to your `create_lucky_num` function doesn’t seem necessary. Instead of hardcoding the size and range of numbers, think about allowing the caller to specify these parameters. Also, remember to protect your header file against multiple inclusions with `#ifndef` or `#pragma once`. It can prevent potential problems in larger projects!

Overall, your code looks good. Just a few points: Make sure you document any functions that allocate memory with malloc, mentioning that the caller should free it afterwards. Also, try separating concerns in your lucky number generation function; it currently mixes logic with error handling. Initialize srand once in your main function to avoid getting the same random numbers if called multiple times quickly. Returning an error code instead of just printing an error and exiting will make your functions more flexible for use in different contexts.