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Back References
Regular Expressions - Extra Elements example from a Well House Consultants training course
More on Regular Expressions - Extra Elements [link] Source code: bref Module: Q803
=head1 Backreference Demonstration A back reference in a regular expression says "now match something that I already matched earlier in this operation". In the following example, we capture the first character of a parameter using () and then check that it's also the last character by using a back reference to the first capture - that's \1 =cut if ($ARGV[0] =~ /^(.).*\1$/) { print "balanced\n"; } else { print "UNbalanced\n"; } __END__ Here's a sample of this running Dorothy:~/j7p grahamellis$ perl bref cheese UNbalanced Dorothy:~/j7p grahamellis$ perl bref melksham balanced Dorothy:~/j7p grahamellis$ Learn about this subject
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This example comes from our "Regular Expressions - Extra Elements" training module. You'll find a description of the topic and some
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