Is the type cast necessary when using malloc in C?

Question

Possible Duplicate:
Do I cast the result of malloc?

I just learned how to use the malloc function, and my teacher mentioned that it's necessary to make a type cast when passing the memory address to the pointer. For example, here's a code to get 16 new bytes allocated (4 ints) using malloc:

#include <stdlib.h>

int main(){
   int *p;
   p = (int *)malloc(4*sizeof(int));

   return 0;
}

My question: is the (int *) cast on the right side of the attribution necessary? After all p is already a pointer to ints, so the pointer arithmetic should work fine even without that cast.

Thanks

score 5 · Accepted Answer · answered Jun 15 '11 at 14:30

5

You only need the cast if you are using malloc in C++ code.

For C it's preferable to not use the cast as it is (a) unnecessary and (b) can mask problems that would otherwise be reported by the compiler.

answered Jun 15 '11 at 14:30

Paul R

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2

And then, it's C++, it's better to use `new` unless you know what you are doing. – Etienne de Martel Jun 15 '11 at 14:31
2

Furthermore, the code can be made a bit more robust by writing `p = malloc(4 * sizeof *p);`. – Keith Thompson Jul 25 '11 at 16:40

Is the type cast necessary when using malloc in C?

1 Answers1