Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!wuarchive!uwm.edu!linac!convex!usenet
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: pack and unpack
Message-ID: <1991May18.130334.10085@convex.com>
Date: 18 May 91 13:03:34 GMT
References: <1991May15.205819.890@lighthouse.com>
Sender: usenet@convex.com (news access account)
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 45
Nntp-Posting-Host: pixel.convex.com

From the keyboard of rob@lighthouse.com (Rob Kedoin):
:I was trying to use pack for the first time today and I can't get the
:following test program to do what I want:
:
:--- cut here ---
:#!/usr/bin/perl
:# packTest.  Experiment with pack.
:#
:# Expected output was:
:# foo
:# bar
:# baz
:#
:# Actual output is:
:# f
:# b
:# b
:
:$struct = pack("aaa", "foo", "bar", "baz");
:
:($foo, $bar, $baz) = unpack("aaa", $struct);
:
:print "$foo\n";
:print "$bar\n";
:print "$baz\n";
:--- cut here ---
:
:Does anyone know why I would only get the first character of the
:string and how to fix this.  

An 'a' format is just one ascii character.  Structures tend to be fixed
format.  You need to specify how long each string is, or at most use a*
for the last one.

    $fmt = 'a10' x 3;
    $struct = pack("aaa", "foo", "bar", "baz");
    ($foo, $bar, $baz) = unpack("aaa", $struct);
    
This doesn't really buy you very much unless you're reading
fixed-format (and often binary) records.

--tom
--
Tom Christiansen		tchrist@convex.com	convex!tchrist
		"So much mail, so little time."