minimal match regulara expression

fionbarr has asked for the wisdom of the Perl Monks concerning the following question:

I have a string that looks like:

wppwd01a0099_NET_basp_virtual_adapter
[download]

I want to capture the chars before the first '_' but what I end up with is:

wppwd01a0099_NET_basp_virtual
[download]

The regular expression I'm trying is:

if ( $this_server =~ m/^(\w+)_/ ) {
             $this_server = $1;
         }
[download]

what am I doing wrong?

Comment on minimal match regulara expression Select or Download Code

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Re: minimal match regular expression by toolic (Bishop) on Mar 03, 2015 at 16:34 UTC
You can use s/// to remove everything after the 1st underscore (inclusive): `use warnings; use strict; my $this_server = 'wppwd01a0099_NET_basp_virtual_adapter'; $this_server =~ s/_.*//; print "$this_server\n"; __END__ wppwd01a0099` [download]	[reply] [d/l]
Re^2: minimal match regular expression by fionbarr (Friar) on Mar 03, 2015 at 16:37 UTC
bravo, thanks	[reply]
Re^3: minimal match regular expression by james28909 (Deacon) on Mar 03, 2015 at 16:56 UTC
you can also: `use warnings; use strict; my $match, $pruned = split(/_/, $_); print $match` [download] at work so cant* test it haha	[reply] [d/l]
Re^4: minimal match regular expression by AnomalousMonk (Archbishop) on Mar 03, 2015 at 20:51 UTC
Re^2: minimal match regular expression by fionbarr (Friar) on Mar 03, 2015 at 19:40 UTC
thanks...this is the one I ended up with after finding out I had some occurances of an internal '-' which choked on (\w+?)	[reply]
Re: minimal match regulara expression by trippledubs (Deacon) on Mar 03, 2015 at 17:19 UTC
You can also use a negated character class to match everything except what you don't want `my ($match) = 'wppwd01a0099_NET_basp_virtual_adapter' =~ /^([^_]*)/; print $match; #wppwd01a0099` [download]	[reply] [d/l]
Re: minimal match regulara expression by Laurent_R (Canon) on Mar 03, 2015 at 18:06 UTC
Hi, the problem with your regex: `if ( $this_server =~ m/^(\w+)_/ ) { $this_server = $1; }` [download] is greedy matching: the expression tries to capture as much as possible until the last "_". Try to change it to a non greedy quantifier (`+?` instead of `+`: `if ( $this_server =~ m/^(\w+?)_/ ) { $this_server = $1; }` [download] Update: Oops, I had not noticed that you actually had found the same solution by yourself (your second post), in part due to the fact that is is poorly formated. BTW, for a closing format tag, you should use a forward slash, not a back slash. Je suis Charlie.	[reply] [d/l] [select]
Re: minimal match regulara expression by fionbarr (Friar) on Mar 03, 2015 at 16:19 UTC
got it: # remove everything after underscore_ 259 if ( $this_server =~ m/^(\w+?)_/ ) { 260 $this_server = $1; 261 }	[reply]