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in reply to Re^2: Regex help
in thread Regex help

What is the reason to put \E at the end of a regexp?

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Re^4: Regex help
by moritz (Cardinal) on May 06, 2009 at 11:53 UTC
    It doesn't make a difference, but if you want to write something after the variable, it's treated literally unless there's an \E. That's a common mistake I made, so I always haven an \E for every \Q.

    Example: 

    $ perl -Mre=debug -e 'my $x= "*"; /\Q$x.+/'
Compiling REx "\*\.\+"
Final program:
   1: EXACT <*.+> (3)
   3: END (0)
anchored "*.+" at 0 (checking anchored isall) minlen 3 
Freeing REx: "\*\.\+"

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    You see that the .+ is also treated literally.
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Re^4: Regex help
by ikegami (Patriarch) on May 06, 2009 at 15:21 UTC
    It's easier to say

    Use /\Q$variable\E/

    than

    Use /\Q$variable/ except if that's not the entire regexp pattern. You probably have to use /\Q$variable\E/ then.

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