replace / with \ using regular expressions?

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

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Re: replace / with \ using regular expressions? by davorg (Chancellor) on Jun 20, 2009 at 13:33 UTC
For replacing a single, known character, then regular expressions are the wrong tool. You need the `tr///` operator as has already been pointed out. The difference in performance is impressive: `$ cat bench #!/usr/bin/perl use strict; use warnings; use Benchmark 'cmpthese'; sub regex_subst { $_ = 'this/is/a/string'; s\|/\|\\\|g; } sub tr_subst { $_ = 'this/is/a/string'; tr\|/\|\\\|; } cmpthese(1_000_000, { s => \&regex_subst, tr => \&tr_subst, }); $ ./bench Rate s tr s 287356/s -- -75% tr 1162791/s 305% -- $` [download] -- See the Copyright notice on my home node. Perl training courses	[reply] [d/l]
Re^2: replace / with \ using regular expressions? by Juerd (Abbot) on Jun 21, 2009 at 23:09 UTC
You need the tr/// operator No, you don't need it. TIMTOWTDI, and s///g is as understandable and easy to write just like tr///. The difference in performance is impressive But typically completely irrelevant for the performance of scripts/programs of any size. This optimization feels pretty immature. When will doing 287356 of these operations per second ever be anything other than fast enough?	[reply]
Re^2: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 14:22 UTC
hi daveorg, Thanks for making this clear to me.	[reply]
Re^3: replace / with \ using regular expressions? by Marshall (Canon) on Jun 20, 2009 at 15:40 UTC
I would just point out that the Perl functions on Windows don't care about / vs \. If you calling a Perl function leave it in a/b/xyz format. Of course a command to the Windows shell is different.	[reply]
Re: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 07:42 UTC
`$command =~ s!/!\\!g; # Swap '/' for '\'`	[reply] [d/l]
Re^2: replace / with \ using regular expressions? by afoken (Chancellor) on Jun 20, 2009 at 08:03 UTC
`tr\|/\|\\\|` should be more efficient. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l]
Re^3: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 14:26 UTC
thanks Alex.	[reply]
Re^2: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 07:46 UTC
I have string say C:/this/is/atest/ i need to replace this with C:\this\is\atest\?	[reply]
Re^3: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 07:56 UTC
What the problem is? `$command = 'C:/this/is/atest/'; $command =~ s!/!\\!g; # Swap '/' for '\' die $command; __END__ C:\this\is\atest\ at - line 3.` [download]	[reply] [d/l]
Re^4: replace / with \ using regular expressions? by Anonymous Monk on Jun 20, 2009 at 08:08 UTC


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