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From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: STDIN waits for ^D, not newline
Message-ID: <1990May9.223157.12674@iwarp.intel.com>
Date: 9 May 90 22:31:57 GMT
References: <5249@crltrx.crl.dec.com>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 52
In-Reply-To: halbert@halbert.crl.dec.com (Dan Halbert)

In article <5249@crltrx.crl.dec.com>, halbert@halbert (Dan Halbert) writes:
| (Using Perl version:
| $Header: perly.c, v 3.0.1.4 90/02/28 18:06:41 lwall Locked $
| Patch level: 15)
| 
| I'm writing an interactive terminal program in perl. It prompts the user
| and reads from STDIN.
| 
| If you try this program:
| 
| print "prompt: ";
| $a = <STDIN>;
| print $a;
| 
| then a carriage return will end the input. (That is, <STDIN> will read
| one line.)
| 
| However, if you try:
| 
| print "prompt: ";
| local ($a) = <STDIN>;
| print $a;
| 
| then STDIN keeps reading input until I type ^D.
| 
| In my program, the local() is in a subroutine, of course, but that isn't
| necessary to reproduce the problem.
| 
| Opening "-" explicitly doesn't solve the problem.
| 
| I just started looking at comp.lang.perl; sorry if this is old hat.

Not old hat.  I don't recall seeing this one before.

But, the problem (without testing it) is that
	local($a) = <STDIN>;
is an _array assignment_.  So, <STDIN>, being very helpful, is sucking
all of standard input into an array, and then giving the first line
into $a, while discarding the rest.
This works better (but looks ugly -- Larry?):

	local($a) = "".<STDIN>;

Which basically says to interpret <STDIN> in a scalar context (a
string concatenation), and pass the result to the assignment.

$|=1;$_=",rekcah lreP rehtona tsuJ";while(length){exit wait if fork;s/.$//;print$&;}
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
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