Page History

...

If stdlib.h is not included, the compiler makes the assumption that malloc() has a return type of int. When the result of a call to malloc() is explicitly cast to a pointer type, the compiler assumes that the cast from int to a pointer type is done with full knowledge of the possible outcomes. This may lead to behavior that is unexpected by the programmer.

char *p = (char *)malloc(10);

...

By ommiting the explicit cast to a pointer, the compiler can determine that an int is attempting to be assigned to a pointer type and will generate a warning that may easily be corrected.

#include <stdlib.h>
...
char *p = malloc(10);

...