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From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.unix,net.lang.c,net.unix-wizards
Subject: Re: Standardized predefined CPP symbols, down with folklore
Message-ID: <2804@watcgl.UUCP>
Date: Mon, 9-Jul-84 17:10:34 EDT
Article-I.D.: watcgl.2804
Posted: Mon Jul  9 17:10:34 1984
Date-Received: Tue, 10-Jul-84 00:30:46 EDT
References: <2065@rlgvax.UUCP>  <142@pyuxt.UUCP>  <8241@watmath.UUCP> <297@watdcsu.UUCP>, <4842@utcsrgv.UUCP>
Organization: U of Waterloo, Ontario
Lines: 4

I think that, once upon a time, the preprocessor *did* #define unix unix.
But at the point that cpp began accepting #if in addition to #ifdef,
the default value of defined parameters changed from themselves to 1.
You can use "1" in both #if and #ifdef.