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

I am trying to escape a charater in a string. For example, if I have a string that looks like this: 

This is my string that has a | in it.

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I want to change it to this: 
This is my string that has a \| in it.

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Now, in this specific case I can do it with this simple statement: 

$_ =~ s/\|/\\\|/g;

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My problem is that the character that needs to be escaped is actually held in a variable ($delim). I tried this: 
$_ =~ s/\{$delim}/\\{$delim}/g;

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But it doesn't work.

I know that I could go character by character through the sring, but that seems kinda ugly.

Any ideas would be really helpful.
thanks.

Replies are listed 'Best First'.
Re: How to 'escape' a character in a string?
by moritz (Cardinal) on May 23, 2012 at 16:35 UTC
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Re: How to 'escape' a character in a string?
by toolic (Bishop) on May 23, 2012 at 16:40 UTC
    quotemeta 
    my $delim = quotemeta '|';
my $s = 'This is my string that has a | in it.';
$s =~ s/($delim)/\\$1/g;
print "$s\n";

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This is my string that has a \| in it.

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Re: How to 'escape' a character in a string?
by ikegami (Patriarch) on May 23, 2012 at 17:33 UTC

    You need to convert the delimiter into a regex pattern that matches the delimiter. That's what quotemeta does. 

    my $pat = quotemeta($delim);
s/$pat/\\$delim/g;

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    quotemeta can be accessed with \Q..\E in regex literals (among others). 

    s/\Q$delim\E/\\$delim/g;

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    or 

    s/\Q$delim/\\$delim/g;     # \E is optional at the end of the literal.

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      Thanks everyone for your help!

      Love learning about new stuff.

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