While trying to get interface name using below code, returned pointer p is crashing. Can someone help?

char *p = NULL, buf[IFNAMSIZ]='';
int i = 0;
for(i=0; i<50; i++)
{
    p = if_indextoname(i,buf);
    if(p == NULL)
        continue;
    printf("p = %s",p);
}

Though pointer address is valid, unable to access its value.

I tried initialising the pointer and the buffer & added null check before printing pointer p. But it didn’t help