Answer 1

scanf expect second argument to be a pointer to the right variable type...

b is already a pointer as it is a char array, so you don't need & prefixing it...

however, h and j requires it to work:

https://code.sololearn.com/cpoyoNpx7ekS/?ref=app

Answer 2

I did not remove & in k: k is only used in printf, wich conversely require the value, not the pointer (except for char array)...

you hadn't any error at printf statements ;)