I just found this code on wikipedia.
Link: http://en.wikipedia.org/wiki/Sizeof#Use

The code:

/* the following code illustrates the use of sizeof 
 * with variables and expressions (no parentheses needed),
 * and with type names (parentheses needed)
 */

char c;

printf("%zu,%zu", sizeof c, sizeof(int));

It states that: "The z prefix should be used to print it, because the actual size can differ on each architecture."

I tried it on my compiler, but it gives the following result:

'zu,zu'