s/// operator

perlUser345 has asked for the wisdom of the Perl Monks concerning the following question:

I've used the s/// operator with great success before. However, this time I'm getting some weird results.

I have this:

$test = "mouse_eatsCat_andDog.txt";
$test =~ s/"_(.+)"/$1/; #because I want to get "eatsCat_andDog.txt"
print "$test";
#result is "mouse_eatsCat_andDog.txt"
[download]

I'm very puzzled by this! I've tried this with no success as well:

$test =~ s/"^mouse_(.+)"/$1/;

I made it work using a different method so that I got only "eatsCat_andDog.txt" but I want to know why the above method doesn't work. Thanks!

Comment on s/// operator Select or Download Code

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Re: s/// operator by BrowserUk (Patriarch) on Nov 19, 2015 at 19:22 UTC
`$test = "mouse_eatsCat_andDog.txt"; $test =~ s/"_(.+)"/$1/; #because I want to get "eatsCat_andDog.txt"` [download] Your string doesn't contain a quote(") followed by an underscore(_), so your regex never matches. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^2: s/// operator by perlUser345 (Acolyte) on Nov 19, 2015 at 19:25 UTC
OMG!!! The dumbest mistake ever! Thank you very much!	[reply]
Re: s/// operator by stevieb (Canon) on Nov 19, 2015 at 19:26 UTC
The latter regex `$test =~ s/"^mouse_(.+)"/$1/;` is very close. The problem is that when you assign a string to a variable (eg: `$test = "blah";`), the quotes are stripped off. So it's the double-quote at the beginning of the regex that is breaking things. To further, `^` denotes the beginning of the string, so the `"` would never match even if there was one embedded in the string. Note though that the second double-quote at the end of the regex will allow the regex to match even though there isn't one in the string, because you capture everything `(.+)` up to it. This works: `$test =~ s/^mouse_(.+)/$1/;` [download]	[reply] [d/l] [select]
Re^2: s/// operator by perlUser345 (Acolyte) on Nov 19, 2015 at 19:31 UTC
Thank you! That was it :)	[reply]
Re: s/// operator by GotToBTru (Prior) on Nov 19, 2015 at 19:26 UTC
Your s/// is not finding any matches to change. "_, for one example, never occurs in your string. Dum Spiro Spero	[reply]