Regexp find all matches

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

Hi,

I have a long html text. For this text I want to get all database
Identifiers (4 letters, beginning with a digit (not 0)) e.g 1TGS
These IDs are introduced by the database name (PDB) e.g.
PDB ID 1TGS || PDB code ID 1TGS || PDB 1TGS.
These terms can occure multiple times in the text.

$string = "<html>Test text PDB code ID 1TGS 1O6S 1TGS bla bla \nPDB code
 1ILW 1ILV"; 
I want to get all these IDs.
this is not correct:
while($string=~/(?<=PDB).+?([1-9][A-Z0-9]{3})/g){ print $1, "\n";}

but how to get all IDs?? Thanks in advance! Yours Murcia

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Re: Regexp find all matches by holli (Abbot) on Mar 03, 2005 at 10:05 UTC
`$string = qq { <html>Test text PDB code ID 1TGS 1O6S 1TGS bla bla PDB code 1ILW 1ILV PDB 2XXX }; while($string=~/PDB (?:code )?(?:ID )?(([1-9][A-Z0-9]{3} ?)+)+/mg){ pr +int $1, "\n";}` [download] holli, /regexed monk/	[reply] [d/l]
Re: Regexp find all matches by tphyahoo (Vicar) on Mar 03, 2005 at 12:43 UTC
In the future when posting about regex help, you may want to use the __DATA__ feature for your test data, explaining which data you want matched/substited/whatever, and which data isn't working. For example, look at Celsius to Fahrenheit using s///. Then it is easier for your brother monks to help you with your problem.	[reply]
Re: Regexp find all matches by manav (Scribe) on Mar 03, 2005 at 10:13 UTC
Is there any reason you are using look-behind?? Your requirement that you state amount to `my (@arr) = $string =~ /[1-9][a-zA-Z0-9]{3}/g ;` Or am I missing something here?? Manav	[reply] [d/l]
Re^2: Regexp find all matches by Murcia (Monk) on Mar 03, 2005 at 10:14 UTC
The reason is, not to find many false positives!	[reply]
Re^3: Regexp find all matches by manav (Scribe) on Mar 03, 2005 at 11:37 UTC
Can you manually list what will be the true positives in this $string $string = "<html>Test text PDB code ID 1TGS 1O6S 1TGS bla bla \nPDB code 1ILW 1ILV"; Manav	[reply]