面試 改錯題-1

Problem

Find as many issues as possible and correct them:
malloc(n) allocates n bytes in the heap.

int main(void)
{
    int *ptr = (int *) malloc(10);
    for(int i =0; i <10; i++)
    {
        *ptr++ = i;
    }
    free(ptr);
}

Solution

1. line 3 -- 10 integers should have the size of 10 * sizeof(int);
2. line 8 -- ptr is not original pointer allocated -- free(ptr - 10)
3. ptr is used without checking its validity
4. missing header files <stdlib.h> or <malloc.h>
5. misssing return statement, but it is ok for main() because it is only one function that can implicitly return 0