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67 lines
1.1 KiB
Perl
67 lines
1.1 KiB
Perl
#Check the frequency!
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#!/usr/bin/perl
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use warnings;
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use strict;
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sub frequency {
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my $text = join('', @_);
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my %letters;
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foreach (split //, $text) {
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$letters{$_}++;
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}
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return %letters;
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}
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my $text = "this is a test";
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my %count = frequency($text);
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foreach (sort keys %count) {
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print "\t", $count{$_}, " '$_", ($count{$_} == 1)? "'": "'s", "\n";
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}
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#Match zero or one characters!
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$p = "This is a pattern test.";
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if ($p =~ /(\w)?/){ print "$1\n"; }
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#To specify a maximum number of occurrences, use 0 as the lower bound.!
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/de{0,3}f/ matches d, followed by no more than three es, followed by f.
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#To specify a minimum number of occurrences, leave off the upper bound.!
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/de{3,}f/ matches d, followed by at least three es, followed by f.
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#Checking for multiple occurrences!
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Pattern Interpretation
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/a{1,4}/ Matches one, two, three, or four as.
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/a{2}/ Matches two as.
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/a{0,2}/ Matches one or two as.
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