Matching condition for two files

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

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Re: Matching condition for two files by Nikhil Jain (Monk) on May 02, 2011 at 07:34 UTC
Try something like `use strict; use warnings; while(<DATA>){ if($_ =~ /M8BBABONP\wM\d+/){ print "Match found\n"; } } __DATA__ M8BBABONPGM100.dat M8BBABONPYM101.dat` [download] Output: Match found Match found	[reply] [d/l]
Re^2: Matching condition for two files by CountZero (Bishop) on May 02, 2011 at 09:57 UTC
Your regex will also match filenames with more than one digit different. Also it will match filenames which will begin with anything else and which have different extensions. To avoid that you will need to anchor the regex: `/^M8BBABONP\wM10\d\.dat$/` [download] CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James	[reply] [d/l]
Re^3: Matching condition for two files by Khen1950fx (Canon) on May 02, 2011 at 16:28 UTC
CountZero++. I had tried it and got stuck in some muck, but I used your regex and a foreach: `#!/usr/bin/perl use strict; use warnings; use Data::Dumper::Concise; my(@array) = ('M8BBABONPGM100.dat', 'M8BBABONPYM101.dat'); foreach my $array(@array) { if ($array =~ /^M8BBABONP\wM10\d\.dat$/){ print "We have a match: \n"; print Dumper($array); } }` [download]	[reply] [d/l]
Re^2: Matching condition for two files by AnomalousMonk (Archbishop) on May 02, 2011 at 12:52 UTC
Assuming the differing letter and digit will always be in the same positions... The character set `\w` also matches digits and _ (underscore). A more specific character set is `[[:alpha:]]` (the set of all alphabetic characters), or `[[:upper:]]` if you know the letter will always be upper-case. Also, heed the advice of CountZero concerning anchoring the ends of the match and file name extensions. See Character Classes and other Special Escapes in perlre, and Posix Character Classes in perlrecharclass.	[reply] [d/l] [select]
Re^2: Matching condition for two files by Anonymous Monk on May 02, 2011 at 07:36 UTC
why no + after \w `if($_ =~ /M8BBABONP\w+M\d+/){` [download]	[reply] [d/l]
Re^3: Matching condition for two files by Nikhil Jain (Monk) on May 02, 2011 at 07:43 UTC
because + used for one or more matching and in this situation we know that only one letter is changing after that letter "M" will come. so for one letter \w is enough.	[reply]
Re^4: Matching condition for two files by Anonymous Monk on May 02, 2011 at 07:46 UTC
Re: Matching condition for two files by Ratazong (Monsignor) on May 02, 2011 at 07:39 UTC
`\a` is the escape-sequence for alarm. You probably want to use `\w` instead (see perlre).	[reply] [d/l] [select]
Re: Matching condition for two files by JavaFan (Canon) on May 02, 2011 at 10:42 UTC
Untested: `sub check { my ($name1, $name2) = @_; return unless length($name1) eq length($name2); my $letter_diff = 0; my $number_diff = 0; for (my $i = 0; $i < length($name1); $i++) { my $ch1 = substr $name1, $i, 1; my $ch2 = substr $name2, $i, 1; next if $ch1 eq $ch2; if ($ch1 =~ /\pL/ && $ch2 =~ /\pL/) {return if ++$letter_diff +> 1; next} if ($ch1 =~ /\pN/ && $ch2 =~ /\pN/) {return if ++$number_diff +> 1; next} return; # Differ in non-letter/non-digits } return $letter_diff == 1 && $number_diff == 1; }` [download]	[reply] [d/l]