Perl Subroutine Arguments

Subroutines:-

1. Retrieving arguments to a subroutine with shift:




A subroutine's arguments come in via the special @_ array. The shift without an argument defaults to @_.

   sub volume {
        my $height = shift;
        my $width = shift;
        my $depth = shift;

        return $height * $width * $depth;
    }

2. Assign arguments to a subroutine with list assignment:

You can also assign arguments en masse with list assignment:

   sub volume {
        my ($height, $width, $depth) = @_;

        return $height * $width * $depth;
    }

3. Handle arguments directly by accessing @_:




In some cases, but we hope very few, you can access arguments directly in the @_ array.

   sub volume {
        return $_[0] * $_[1] * $_[2];
    }

references:

• http://perl101.org/subroutines.html
• https://www.tutorialspoint.com/perl/perl_subroutines.htm

This note explains how Perl subroutines receive their arguments. All arguments arrive in the special @_ array, and a bare shift inside a subroutine defaults to shifting from @_, which is the idiomatic way to read them one by one.

Pulling arguments into named variables at the top of a subroutine makes the rest of the code clearer than indexing @_ directly throughout.