perl - help understanding pattern matching in regex

Posted by hatorade on Stack Overflow See other posts from Stack Overflow or by hatorade
Published on 2010-04-29T07:53:30Z Indexed on 2010/04/29 7:57 UTC
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perl

|

regex

$line =~ /^(\d+)\s/; 
next if(!defined($1) ) ;
$paperAnnot{$1} = $line;

What is the $1? Is that the match found for (\d+)?

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