I dont understand why it returns "You must return a given string" when i allocate memory in the variable "binary" I did the same but without allocating memory and it works, why?

I allocated memory in * binary and I store the bits on it and the last line of the fucntion is return binary
thats all, i dont know why there is always an error or a bug in my code that doesnt seem to have an explanation, C language has been a pain in my head, sometimes the IDe doesn even print the expected result and nothing happens, I have to search deep for some answers before knowing what is the problem.

Hello I am trying to solve this kata but it gives me this error

"You must return the given string"

apparently everything works fine because I tested the code in other IDE bit I dont know what i am doing wrong, help me please

why to declare newarr as a NULL the first lines if there will be memory allocated in it?

hello, how does it work?
what kind of wicthcraft is this?

why is it better?

hello, could anyone explain to me this challenge please, i dont get it