Re^2: Unknown numbers show up

Dear Athanasius,

I would like to thanks you for the detail explaining the logic behind why the extra number show up.

However, I still not really know how to solve the issue. As I am dealing with 2 files with each 8 million of line. I have to use your second proposal on the assertion to match the comma.

As this is my first write up, I am not really sure how to edit this particular code:- $command_line = "perl -pi\.bak -e s\/".$search."\/".$replace."\/g\; CombineDie1Die2.txt";

to what you had mentioned :- s/WL0,BL1(?=,)/WL0,BL1,1708/g;

I meant how to insert or where to include this (?=) specifically.

Regards, Vkhaw

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Re^3: Unknown numbers show up
by Athanasius (Archbishop) on Apr 12, 2015 at 16:02 UTC

Like this:

my $command_line = 'perl -pi.bak -e s/' . $search . '(?=,)/' . $replac
+e . '/g; CombineDie1Die2.txt';
#                                           Add this ^^^^^
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(See “Look-Around Assertions” in perlre#Extended-Patterns.)

By the way, there is another problem with your code: the command switch -pi.bak makes a backup of the target file each time a substitution is applied. This means that CombineDie1Die2.txt.bak ends up almost the same as CombineDie1Die2.txt (only the final substitution is omitted). This is almost certainly not what you want. It provides yet another reason to follow flexvault’s advice and remove the nested calls to Perl one-liners from within your script. Much better to re-cast the logic and use Perl’s substitution facilities, etc., directly, rather than invoking a new Perl interpreter millions of times!

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re^4: Unknown numbers show up

by Vkhaw (Novice) on Apr 12, 2015 at 16:24 UTC

Yes, I will try to further change to script to more effective. The bak file was created because I was using the liner command and without the .bak file created it show error.

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