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From: jwp@sdchema.UUCP (John Pierce)
Newsgroups: net.unix-wizards
Subject: Re: Yet even MORE Csh Quirks
Message-ID: <369@sdchema.UUCP>
Date: Fri, 19-Apr-85 19:22:28 EST
Article-I.D.: sdchema.369
Posted: Fri Apr 19 19:22:28 1985
Date-Received: Sun, 21-Apr-85 23:49:13 EST
References: <10032@brl-tgr.ARPA>
Reply-To: jwp@sdchema.UUCP (John Pierce)
Organization: Chemistry Dept, UC San Diego
Lines: 79

In article <10032@brl-tgr.ARPA> argv@ucb-vax.ARPA writes:

 > ... It seems that "endif"'s don't know who they are ending.  Exibit A:

 > #!/bin/csh -f
 > @ count = 0
 > if($#argv == 2) then
 >     echo hi there
 >     if( 1 ) then  # this statement if obviously a no-op.
 > 	@ count++  # count should be 1
 > 	echo true
 >     endif
 >     echo hi there again
 >     @ count++      # count should be 2
 > endif
 > echo count = $count  
 > 
 > if argv is NOT 2, then $count should be 0, right?!
 > else count should be 2...  but in ANY event, count
 > should NEVER be 1. Also, you should either see, 
 > "hi there" AND "hi there again" or NEITHER, am I right?

No, not really.

 > The fault lies in the fact that you can't have nested if statements....

You can have nested 'if' statements.  The "fault" lies in a syntax error.  The
two 'if' statements should be

	if ($#argv == 2)
and
	if (1)

While it is annoying, that space between 'f' and '(' is necessary for csh to
handle the statement properly [the manual entry *does* specify "if (expr)..."].
It is also the case that

	if (expr1) then
		stmt1
	else
		if (expr2) then
			stmt2
	endif

is handled differently from

	if (expr1) then
		stmt1
	else if (expr2) then	# Syntax specified by the manual
		stmt2
	endif

when either the "if" portion or the "else" portion contains further "if"
statements.  I believe, though it's been a long time since I tested all of
this, that there are also problems with "while" and "foreach" inside improperly
typed "if" statements.  I do remember that

	while(expr)
		...
		while(expr)
			...
		end
		...
	end

(and the equivalent "foreach") also break, since the specified syntax is

	while (expr)		foreach (expr)

I have forgotten whether or not the space is absolutely necessary in "switch"
statements, but I believe it is.  While having to have the space there seems
dumb, with it things work as you would expect; without it, they do not.  The
problem can be fixed in the source, though it isn't completely trivial [meaning
it didn't seem to be sufficiently trivial for me to waste time on a problem
that doesn't annoy me any more than this one does].

				John Pierce, Chemistry, UC San Diego
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