Re: $1 don't reset (non loop)

from the perlre manpage: The numbered variables ($1, $2, $3, etc.) and the related punctuation set ("$+", "$&", "$`", and "$'") are all dynamically scoped until the end of the enclosing block or until the next successful match, whichever comes first.

So $1 is only set if the match succeeds, that's why it's a good idea to write

if ($adress1 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,]*)$/) {
    $adress1 = $1;
}
if ($adress2 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,]*)$/) {
    $adress2 = $1;
}
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snowcrash

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Re: Re: $1 don't reset (non loop) by Skeeve (Parson) on Feb 17, 2004 at 11:35 UTC
If I see it right, you didn't get it quite correct. $addressX should become undef if no match. So this should work: `if ($adress1 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/) { $adress1 = $1; } else { $adress1 = undef; } # and so on...` [download] ~~which should be reducable to:~~ Which is not, as you'll see below, reducable to: `{ $adress1 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/) $adress1 = $1; } { $adress2 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/) $adress2 = $1; }` [download] Update:* Thanks to Abigail-II who found out my mistake.	[reply] [d/l] [select]
Re: $1 don't reset (non loop) by Abigail-II (Bishop) on Feb 17, 2004 at 11:56 UTC
No, not really. That only works if `$1` happens to be undefined. Which you can't count on. Watch: `#!/usr/bin/perl use strict; use warnings; "meep" =~ /(.)/; # Set $1. my $address1 = "Tsjakka"; # Will match. my $address2 = "Tsjakka!"; # Will not match. { $address1 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/; $address1 = $1; } { $address2 =~ /^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/; $address2 = $1; } print $address1, "\n"; print $address2, "\n"; __END__ Tsjakka meep` [download] $address2 doesn't become undef. The solution is much simpler. The regex will either match the entire string, or there's no match. So, we could just do: `/^([A-Za-z0-9鲣逯呐][A-Za-z鲣逯呐0-9\s\-\.\,])$/ or $_ = undef for $address1, $address2;` [download] Abigail	[reply] [d/l] [select]