Re^2: Non-greedy regex behaves greedily

Your regex doesn't force a non-greedy behaviour.

I'll try to explain with a simplified text example:

my $text = <<TEXT;
000ABCDEFABCGHI
TEXT

if ( $text =~ m{(ABC.*?)$} ) {
    print $1, $/;
}
[download]

The engine reads $text from left to right and will have a try with starting at the first "ABC", using the complete following string until end of line. As that's exactly what the regex requested, this result is returned. There's no condition which forces the engine to search for a shorter result. There will be no second run which checks, if the current result may contain a shorter result.

The first valid match will be returned; this isn't always the best match.

Comment on Re^2: Non-greedy regex behaves greedily Download Code

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Re^3: Non-greedy regex behaves greedily by kovacsbv (Novice) on Jul 27, 2008 at 23:36 UTC
Ok, is there a nice detailed description of the engine that would fill in what causes a second run and what the "?" does exactly? This behavior isn't very intuitive. Also, is there another way to get the desired result other than the ugly hack I posted below?	[reply]
Re^4: Non-greedy regex behaves greedily by ysth (Canon) on Jul 28, 2008 at 10:03 UTC
You can force the regex engine to start looking for `</a>` at the end of the string and work forwards by consuming all the string to start with and backtracking character by character: `my $string = q!Back to STATES Menu</font></a></h3> <p align="center">< +a href="index.htm"><img src="home2.gif" alt="Home" border="0" width=" +106" height="30"></a></p> </body> </html>!; if ( $string =~ m!^.(</a>.?)$! ) { print "got $1\n"; }` [download] but there's usually a better way to get what you want done. -- Online Fortune Cookie Search Office Space merchandise	[reply] [d/l] [select]


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