From: "Mark J. Reed" <markjreed@...>
Date: 2003-09-18T00:03:18+09:00
Subject: Re: Ruby and OOP-design (question of an old "procedural person" ;)

On Mon, Aug 11, 2003 at 08:44:23AM +0900, Dan Doel wrote:
> I'm not sure about C, but I would assume it is, because there's no 
> booleans in C so it'd be totally useless
> as it would do the exact same thing as &.

No, it wouldn't.   C doesn't have a Boolean *type*, but it does
have the idea of truth and falsehood (needed for if statements, etc).
Nonzero is true and zero is false.  Which means that this expression:

	1 & 2

is false - bitwise AND of 1 and 2 yields 0.  Whereas 

	1 && 2

is true, because both 1 and 2 are true (nonzero).  The big difference in C
is that the double-characters are LOGICAL operators, while the single
ones are BIT operators.

However, it happens that the logical operators in C and derivatives
also short-circuit, which means you can do things like

	if (p != NULL && strcmp(p->value, key)==0)
	{

and not worry about the program blowing up because the strcmp() is called
when p is NULL.

-Mark