perl - Extracting string with regex stored in hash -

i'm trying parse out specific values text file, , output different file.

i'm using regular expressions stored in hash (matched descriptive name) search through string (scalar), , storing discovered values in array, written out file.

i've got working, except searching/extracting part. (i've learned perl in past couple days, wouldn't surprised if making simple mistakes.)

$inputstring = 'lorem ipsum dolor date: 20110131 quis semper egestas.';  %myregexhash = ( date => '/([12][09][0-9][0-9][0-1][0-2][0-9][0-9])/' );  @foundvaluesarray=();  while ( ($thefieldname, $theregex) = each (%myregexhash)) {     if ($inputstring =~ $theregex)      {         push(@foundvaluesarray, "$thefieldname: $&\n");         $inputstring = $';     } }  print "@foundvaluesarray"; 

the array fills field names ("date:"), not values i'm looking ("20110131").

any idea i'm doing wrong?

make 1 small change:

%myregexhash = ( date => qr/([12][09][0-9][0-9][0-1][0-2][0-9][0-9])/ ); 

note use of qr//, compiles regex.

you're new, i'd recommend few other changes.

any non-trivial program should begin following front matter:

#! /usr/bin/env perl  use strict; use warnings; 

the strict pragma has nice benefits such catching misspelled variable names @ compile time , checking use of references. warnings pragma turns on warning diagnostics can alert questionable cases in code.

now must predeclare:

my $inputstring = 'lorem ipsum dolor date: 20110131 quis semper egestas.';  %myregexhash = ( date => qr/([12][09][0-9][0-9][0-1][0-2][0-9][0-9])/ );  @foundvaluesarray=(); 

the = () implied in array or hash declaration, don't see in idiomatic perl.

you don't want use $& if can because slows down entire program.

warning: once perl sees need 1 of $&, $`, or $' anywhere in program, has provide them every pattern match. may substantially slow program. perl uses same mechanism produce $1, $2, etc., pay price each pattern contains capturing parentheses. (to avoid cost while retaining grouping behaviour, use extended regular expression (?: ... ) instead.) if never use $&, $` or $', patterns without capturing parentheses not penalized. avoid $&, $' , , $` if can, if can't (and algorithms appreciate them), once you've used them once, use them @ will, because you've paid price. of 5.005, $& not costly other two.

because surrounded pattern parentheses, substring matched captured in $1, grab there.

also, way chopped off front of $inputstring more naturally expressed in perl s///.

while (my ($thefieldname, $theregex) = each (%myregexhash)) {     if ($inputstring =~ s/$theregex//)      {         push(@foundvaluesarray, "$thefieldname: $1\n");     } }  print "@foundvaluesarray"; 

output:

date: 20110131