Regex, query

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

HI,

i am trying to create a variable which contains a reference number matched from within a text string.

example,

textstring = Michael please look at E123456

where E123456 is a reference number i need to look at. i want this reference number to be added to a variable called $lookatref. The string is always in the same format, NAME please look at REF. The ref can be either one letter followed by 6 numbers or just 7 numbers

the code im using is

$lookatref = "";
$mystring2 = 'please look at ';
if ($reqtext =~ m/$mystring2(.*?) /i) {$lookatref = $1;}
[download]

$reqtext is the text i want to match. this is read into the variable earlier in the script. i think it is something to do with the regex syntax, but i just cant figure out what it wrong.

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Re: Regex, query by Ratazong (Monsignor) on Jan 24, 2013 at 15:55 UTC
It works for me. Are you sure there is a whitespace after E123456? If you are sure that the REF is the last element in the input, you might want to use a greedy capture instead: change `(.?)` to `(.)` Alternatively, you could append a whitespace to your input before applying the regex (`$reqtext .= " ";`) HTH, Rata	[reply] [d/l] [select]
Re^2: Regex, query by dmsparts (Sexton) on Jan 24, 2013 at 16:13 UTC
Thanks. adding the whitespace at the end did the trick.	[reply]
Re: Regex, query by SuicideJunkie (Vicar) on Jan 24, 2013 at 15:57 UTC
The non-greedy `.*?` will happily match zero characters and quit if it can. Why not have it capture the thing you're looking for (`[a-z]?[0-9]{6,7}`) instead?	[reply] [d/l] [select]
Re: Regex, query by kennethk (Abbot) on Jan 24, 2013 at 16:03 UTC
Assuming your input string is `'Michael please look at E123456'`, your regular expression expects a trailing space that is not there. Rather than looking for trailing white space, perhaps you'd like the non-whitespace character class `\S` (`m/$mystring2\s(\S)/i`)? See Using character classes. #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]