zero sized allocation using malloc

int main()
{
    int *p = 0;
    printf("before addr: %pn", p);
    p = (int *) malloc(0);
    printf("after addr: %pn", p);
    printf("sizeof: %un", sizeof(*p));
    *p = 1;
    printf("--- %d -- this is the last statment.n", *p);
    free(p);
}

Output
before addr: (nil)
after addr: 0x80496c8
sizeof: 4
--- 1 -- this is the last statment.

Note :
Linux

• allows a ‘read’ of the zero sized allocated memory
• allows a ‘write’ on the zero sized allocated memory
• sizeof shows an allocation of 4 bytes.