Introduction to Perl Programming
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The document presents an introduction to Perl programming, covering various essential topics such as data types, control structures, functions, and modules. It emphasizes Perl's interpreted nature, flexibility, and historical context as a scripting language. Additionally, it provides examples for getting started with Perl and defines key concepts such as arrays and subroutines.
![Functions and Subroutines
func2.pl:
firstSub(1, 2, 3, 4, 5, 6);
firstSub(1..3);
firstSub("A".."Z");
sub firstSub() {
$numParameters = @_ ;
print("The number of parameters is $numParametersn");
}
func4.pl|:
@array = (0..5);
print("Before function call, array = @arrayn");
firstSub(@array);
print("After function call, array = @arrayn");
sub firstSub{ $_[0] = "A"; $_[1] = "B";}
This program prints:
Before function call, array = 0 1 2 3 4 5
After function call, array = A B 2 3 4 5}
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Introduction to Perl Programming
- 1. Introduction to Perl Programming www.collaborationtech.co.in Bengaluru INDIA Presentation By Ramananda M.S Rao
- 2. Content Content Overview Get Started Functions & Subroutines Regular Expressions and Patterns Basic Input and Output Formatting and Reporting System Interaction and Process OOPS Concepts Modules ,Packages and Namespaces Project About Us www.collaborationtech.co.in
- 3. Overview Perl is an interpreted language, meaning that a control program that understands the semantics of the language and its components (the interpreter) executes program components individually as they are encountered in the control flow. Interpreted execution makes Perl flexible, convenient, and fast for programming, with some penalty paid in execution speed. Perl programs are often called scripts because of its historical development as an extension of the Unix command-level command scripting notations. www.collaborationtech.co.in
- 4. Get Started #!/usr/bin/perl # This will print "Hello, World" print "Hello, worldn"; #!/usr/bin/perl print("Hello, worldn"); print "Hello, worldn"; #!/usr/bin/perl print "Hello, worldn"; print 'Hello, worldn'; www.collaborationtech.co.in
- 5. Data Types #!/usr/bin/perl $number = 2; $st1 = ‘one fine $number day’; $st2 = “$number fine day n”; print $st2; print “$st1n”; #!/usr/bin/perl $v1 = 127; $v1 = $v1 . ", and more !!"; # . Indicates to concatenate two data print $v1, “n”; $v1 = 127; print $v1 + "151 ", "n"; print $v1 + ", and more !!", "n"; www.collaborationtech.co.in
- 6. Data Types #!/usr/bin/perl my @array = (10, 20, 30); # Assign list variables to scalar variables my $scalar1; my $scalar2; my $scalar3; ($scalar1, $scalar2, $scalar3) = @array; print "Scalar one is $scalar1n"; print "Scalar two is $scalar2n"; print "Scalar three is $scalar3n"; Adding to an Array #!/usr/bin/perl # addelem.pl use warnings; use strict; my @array1 = (1, 2, 3); my @array2 = (@array1, 4, 5, 6); print "@array2n"; @array2 = (3, 5, 7, 9); @array2 = (1, @array2, 11); print "@array2n"; >perl addelem.pl 1 2 3 4 5 6 1 3 5 7 9 11 www.collaborationtech.co.in
- 7. Control Structure If / elsif / else if ($thresh < 10) { # … the ‘then’ block of the conditional } elsif ($thresh < 20) { # the next block in the decision tree } elsif ($thresh < 40) { # and the next… } else { # the final clause catches what falls through } #!/usr/bin/perl # conditional.pl use strict; use warnings; my ($x, $y) = @ARGV; if ($x == $y) { print "equaln"; } else { print "not equaln"; } www.collaborationtech.co.in
- 8. Functions and Subroutines func2.pl: firstSub(1, 2, 3, 4, 5, 6); firstSub(1..3); firstSub("A".."Z"); sub firstSub() { $numParameters = @_ ; print("The number of parameters is $numParametersn"); } func4.pl|: @array = (0..5); print("Before function call, array = @arrayn"); firstSub(@array); print("After function call, array = @arrayn"); sub firstSub{ $_[0] = "A"; $_[1] = "B";} This program prints: Before function call, array = 0 1 2 3 4 5 After function call, array = A B 2 3 4 5} www.collaborationtech.co.in
- 9. Functions and Subroutines #!/usr/bin/perl # gc.pl use strict; use warnings; while (my $seq = <>) { chomp($seq); gc($seq); 8. } sub gc { my ($seq) = @_; $seq = uc($seq); # convert to upper case to be sure my $g = $seq =~ tr/G/G/; my $c = $seq =~ tr/C/C/; my $gc = ($g + $c) / length($seq); print "GC% = $gcn"; } }; www.collaborationtech.co.in
- 10. Modules A module is a package contained within an external file of the same name .pm extension file MyMod.pm: package MyMod; #no shebang!! use strict; use warnings; our ($foo, $bar, $baz); ($foo, $bar) = split /s+/, 'Hello World'; $baz = 42; 1; www.collaborationtech.co.in
- 11. Packages #!/usr/bin/perl use warnings; #note no use strict! $foo = 'Hello'; #sets $main::foo package Bar; $foo = 'World'; #sets $Bar::foo package Lalli; print "$main::foo $Bar::foon"; prints "Hello Worldn" www.collaborationtech.co.in
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- 13. About Us