Casting 0 to \0 (or 0x0)

gistfile1.txt

stupid_null_cast_trick.c

/*
Here's a stupid c trick, a variant of 
which can come up when doing 
`char` and `char *` operations. For an example, 
an older version of make (ca. 1994) traversed 
a char[] and returned the pointer position of 
a `#` to indicate the start of a comment.  This 
produces a warning in gcc now.

Here's the code:
*/

#include <stdio.h>
int
main() {
   printf("(char *)0: %p, %d\n", (char *)0, (char *)0);
   return 0;
}

/*
Compile this code with `gcc -Wall -pedantic char0.c`

I get this for compiler output in gcc 4.4: 

char0.c: In function ‘main’:
char0.c:4: warning: format ‘%d’ expects type ‘int’, but argument 3 has type ‘char *’


Run it: 

$ ./a.out
(char *)0: 0x0, 0
$

Why is this important?  If you have to test for pointer position on
a desired character, and that character doesn't exist, make sure 
the test is against something appropriate.  `cast` is your friend here.

If this bothers anyone, take it up with Roland.
*/