Why my compiler gives me warnings?

Question

#include <stdio.h>
void *square(const void *num);
int main()
{
int a = 5;
int result;
result = square(&a); /*Assignment makes integer from pointer without a cast.*/
printf("%d squared is %d", a, result);
return 0;
}
void *square(const void *num)
{
int r;
r = (*(int*)num)*(*(int*)num);
return r; //return makes pointer from integer without a cast.
}

Answer 1

You declare the function as void* and it means that the function does not expect a return statement within itself. Make it an int function. Also make it's parameter int or const int.

Answer 2

I already did, but it still gives me warnings... According to the comments on "Functions using void pointers", they said to do:
-> return (int*) r;
-> (int)square(&a);
I did the above and it works, but why doesn't Sololearn tell me that in the tutorial? Also, why doesn't it be like this: return (int)r. I thought (int*) is for pointer, isn't it? Please answer...

Answer 3

Ok I began to understand a bit more... thanks :)

Answer 4

Why do you use void* in the first place?

Answer 5

Because I followed the tutorial.

Answer 6

My question is still not answered...

Answer 7

Maybe you should use static int r for the declaration of r variables.