Help with function pointers (C)

Question

https://code.sololearn.com/caZnuh2493H2/?ref=app

First of all, how do I fix this warning? Is it even necessary? Also, I don't get why setting the parameter as a pointer works, but setting it as a normal variable doesn't. C is so hard.

Answer 1

if (num[i] && 0 == 0)