Match and extract three characters from the middle of a string

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

This is a very simple problem, and I feel pretty stupid asking. I have tried working thru this by reading the Regular Expression tutorial Perl doc, but I'm missing something here...

What I need to to match three characters from the middle of a string. For instance, the string 23D78000, I need to simply extract the D78 to input into a database table. My only stumbling point is the actual regexp match. Here is the latest of several things I have tried. Please don't hurt yourselves laughing...

$inq = "23D78000";
($junk, $emc_device, $junk1) = ($inq =~ /(\w\w)(\w\w\w*$/);
[download]

Code tags and formatting added by GrandFather

2006-07-22 Retitled by Arunbear, as per Monastery guidelines
Original title: 'Simple regex matching problem...'

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Re: Match and extract three characters from the middle of a string by ikegami (Patriarch) on Jul 21, 2006 at 19:48 UTC
`my $emc_device = substr($inq, 2, 3);` [download] which is the faster equivalent of `my ($emc_device) = $inq =~ /^..(...)/;` [download]	[reply] [d/l] [select]
Re: Match and extract three characters from the middle of a string by chargrill (Parson) on Jul 21, 2006 at 19:49 UTC
You were close :) First, your code won't compile, unless you've accidentally transposed some characters in typing it in over here. Second, This might do what you want: `$inq = '23D78000'; if( $inq =~ m/^[0-9]{2}([A-Z][0-9]{2})[0-9]+$/ ){ $emc_device = $1; }` [download] Alternatively, if you really like the style you're using above, `$inq = '23D78000'; ( $emc_device ) = $inq =~ m/^[0-9]{2}([A-Z][0-9]{2})[0-9]+$/;` [download] Note that unless you want to keep `$junk` and `$junk1`, you don't need to capture them with parens. But if you DO want to keep them, this will work: `$inq = '23D78000'; ( $junk, $emc_device, $junk1 ) = $inq =~ m/^([0-9]{2})([A-Z][0-9]{2})( +[0-9]+)$/;` [download] Also, if the number of digits in front of your emc_device changes, you'll need to slightly adjust your regex, or perhaps make it more flexible. --chargrill `$,=42;for(34,0,-3,9,-11,11,-17,7,-5){$.=pack'c'=>$,+=$_}for(reverse s +plit//=>$ ){$%++?$ %%2?push@C,$_,$":push@c,$_,$":(push@C,$_,$")&&push@c,$"}$C[$# +C]=$/;($#C >$#c)?($ c=\@C)&&($ C=\@c):($ c=\@c)&&($C=\@C);$%=$\|;for(@$c){print$_^ +$$C[$%++]}` [download]	[reply] [d/l] [select]
Re: Match and extract three characters from the middle of a string by neilwatson (Priest) on Jul 21, 2006 at 19:41 UTC
Assuming you always have 8 characters then `m/\w{2}(\w{3})\w{3}/ $emc_device = $1` [download] Neil Watson watson-wilson.ca	[reply] [d/l]
Re: Match and extract three characters from the middle of a string by planetscape (Chancellor) on Jul 22, 2006 at 02:19 UTC
FWIW, these are my most frequently used resources for constructing/understanding regexes: Mastering Regular Expressions perlrequick perlretut perlre YAPE::Regex::Explain GraphViz::Regex The Regex Coach (Win32 only, IIRC) HTH, planetscape	[reply]
Re: Match and extract three characters from the middle of a string by perlsen (Chaplain) on Jul 22, 2006 at 03:30 UTC
Hi svnipp, If you want to extract D78 like format text you may try this, `$inq = "23D78000"; ($junk, $emc_device, $junk1) = ($inq =~ /^(.*)(\w{3})(\w{3})$/); print "Result: [$junk], [$emc_device], [$junk1]"; #Result: [23], [D78], [000]` [download] Regards, perlsen	[reply] [d/l]
Re: Match and extract three characters from the middle of a string by rsriram (Hermit) on Jul 22, 2006 at 06:14 UTC
Hi, You can also use `substr` to extract a part of the stirng. `$inq="23D78000";` `print substr($inq,2,3);` prints the output you need. `substr` can be used to extract parts of variable. It takes 3 parameters. First is the variable you need to work on, second is the number of characters that needs to be stripped out from left and third is the number of characters that needs to be retained in the string. Hope this helps!!! For further information, see manpage for `substr()`	[reply] [d/l] [select]
Re: Match and extract three characters from the middle of a string by sh1tn (Priest) on Jul 22, 2006 at 10:34 UTC
Just count carefully: `# . (dot) symbol means any character # take 3rd, 4th and 5th chars $inq =~ m\|..(...)\|; print $1;` [download]	[reply] [d/l]
Re: Match and extract three characters from the middle of a string by Leviathan (Scribe) on Jul 22, 2006 at 13:26 UTC
And if the string is variable in length, `my $emc_device = substr($inq, (length($inq) - 3)/2, 3);` [download] -- Leviathan	[reply] [d/l]