Am trying to replace all `` with a HTML code tag
replace:
$string = "Foo `FooBar` Bar";
with:
$string = "Foo <code>FooBar</code> Bar";
i tried these
$pattern = '`(.*?)`';
my $replace = "<code/>$&</code>";
$subject =~ s/$pattern/$replace/im;
#And
$subject =~ s/$pattern/<code/>$&</code>/im;
but none of them works.
Assuming you meant $string instead of $subject...
use strict;
use warnings;
use v5.10;
my $string = "Foo `FooBar` Bar";
my $pattern = '`(.*?)`';
my $replace = "<code/>$&</code>";
$string =~ s{$pattern}{$replace}im;
say $string;
This results in...
$ perl ~/tmp/test.plx
Use of uninitialized value $& in concatenation (.) or string at /Users/schwern/tmp/test.plx line 9.
Foo <code/></code> Bar
There's some problems here. First, $& means the string matched by the last match. That would be all of `FooBar`. You just want FooBar which is inside capturing parens. You get that with $1. See Extracting Matches in the Perl Regex Tutorial.
Second is $& and $1 are variables. If you put them in double quotes like $replace = "<code/>$&</code>" then Perl will immediately interpolate them. That means $replace is <code/></code>. This is where the warning comes from. If you want to use $1 it has to go directly into the replace.
Finally, when quoting regexes it's best to use qr{}. That does special regex quoting. It avoids all sorts of quoting issues.
Put it all together...
use strict;
use warnings;
use v5.10;
my $string = "Foo `FooBar` Bar";
my $pattern = qr{`(.*?)`};
$string =~ s{$pattern}{<code/>$1</code>}im;
say $string;
$1 without putting it directly to replace. like making something like $replace = '<code>$i</code>'
s{}{}e the right hand side will be eval'd as if it were code. But now you're vulnerable to code injection. It works like interpolation. my $foo = 23; my $bar = q[this $foo]; print "$bar" will say this $foo. But if you print eval qq["$bar"] you get this 23... but $bar could contain any code.$1 in strings like PHP does in Example #1. There might be away to do it, but I don't know it. I'd suggest asking that as a new question.
$stringbut you're doing thes///on$subject. Could you show your actual code? And could you show what doesn't work?