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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!whuxl!whuxlm!akgua!gatech!seismo!mcvax!ukc!stc!inset!james
From: james@inset.UUCP (James Dalby)
Newsgroups: net.text
Subject: Ditroff curiosity (bug?)
Message-ID: <819@inset.UUCP>
Date: Thu, 12-Dec-85 07:22:58 EST
Article-I.D.: inset.819
Posted: Thu Dec 12 07:22:58 1985
Date-Received: Mon, 16-Dec-85 05:04:33 EST
Reply-To: james@inset.UUCP (James Dalby)
Organization: The Instruction Set Ltd., London, UK.
Lines: 36
Xpath: stc stc-a

I wonder whether anyone has come across this problem before, or knows the
cause of it.

The following ditroff input:

.de W
.nr f \\$1
.tm f is \\nf
.if \\nf==0 .tm f should be 0, is \\nf
.if \\nf==1 .tm f should be 1, is \\nf
.if \\nf==2 .tm f should be 2, is \\nf
..
.W 0
.W 1
.W 2

when run with

	troff foobar > /dev/null
	
gives this output (honestly)

f is 0
f should be 1, is 0
f is 1
f should be 0, is 1
f is 2
f should be 0, is 2

I know it looks the wrong way round, but it's really true (on my troff).
It works as expected with my nroff.

I tried a few other varieties, and it seems to be only the single letter
register f that mucks everything up.

James.