Perl Regular Expressions

This tutorial is also available for download as PDF document Learn Perl by Example - Perl Handbook for Beginners - Basics of Perl Scripting - Perl Regular Expressions. Searching for a string ------------------------------ #!/usr/bin/perl -w $exp = "This is a string"; if ($exp =~ /This/) {         print ("String Matches!\n"); } Searching for a string using case insensitive -------------------------------------------------------------- #!/usr/bin/perl -w $exp = "This is a string"; if ($exp =~ /tHis/i) {         print ("String Matches!\n"); } Searching for a digit ---------------------------- #!/usr/bin/perl -w $exp = "This is 8 string"; if ($exp =~ /\d/) {         print ("String Matches!\n"); } Searching for 2 digits ----------------------------- #!/usr/bin/perl -w $exp = "This is 88 string"; if ($exp =~ /\d\d/) {         print ("String Matches!\n"); } Searching for whitespaces ------------------------------------- #!/usr/bin/perl -w $exp = "This is string"; if ($exp =~ /\s/) {         print ("String Matches!\n"); } Searching for a string that begins with a pattern ---------------------------------------------------------- #!/usr/bin/perl -w $exp = "This is string"; if ($exp =~ /^This/) {         print ("String Matches!\n"); } Searching for a string that ends with a pattern ---------------------------------------------------------------- #!/usr/bin/perl -w $exp = "This is string"; if ($exp =~ /string$/) {         print ("String Matches!\n"); } Search for a digit with white space in front and after it. -------------------------------------------------------------------------- #!/usr/bin/perl -w $exp = "This 1 is string"; if ($exp =~ /\s\d\s/) {         print ("String Matches!\n"); } Search for a blank line ------------------------------ This is usefull  to check for blank lines in a file. For that, instead of $exp variable you will need an array that will contain every line from that file. #!/usr/bin/perl -w $exp = ""; if ($exp =~ /^$/) {         print ("String Matches!\n"); }  Replace a pattern ------------------------ #!/usr/bin/perl -w $exp = "This is a string"; if ($exp =~ s/This is/Test/) {         print ("$exp\n"); }

 

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