Perl: Variables and Functions

I have written Perl scripts for a long time (around 3 years?). However, since my programming style is so mixed: Perl, Matlab, C, Fortran, Mathematica, and their concept/syntax confuse me after not using it for some time. Here I summarize how the variables and functions are used.

Variables: Scalar, Arrays, Hash (not used much)

1. Scalar

    Define:  $variable

    Access:  $variable

2. Array

    Define:  @variable

    Access:  For each element, $variable[0]; to get the whole array @variable

Functions: define function, function input, function return

1. Define a Function: use sub to define, use & to call the function

#! /usr/bin/perl -w

use strict;

sub TestPrint{

    return "Test and Print\n";

}

&TestPrint;

2. Reference: similar as pointer in C, it is often used to pass value into/out of subroutine.

Subroutine take zero or more scalar arguments as input (and possibly output), and they return zero or one scalar as a return value.

2. Function Input: the @_ is input arguments, better to first convert it into private variables

#! /usr/bin/perl -w

use strict;

sub TestPrint {

   my($test1, @test2) = @_;

   my $test_print;

   foreach my $test_tmp (@test2) {

       $test_print .= "$test1, $test_tmp!\n";

   }

   print "$test_print\n";

}

my @name;

$name[0] = "Pan";

$name[1] = "Yue";

$name[2] = "TinTin";

&TestPrint("Hi", @name);

&TestPrint("Hi", "Pan", "Yue", "TinTin");

3. Function Return: return can be scaler, arrays or hash, better to use explicitly "return"

Good Reference from "http://www.troubleshooters.com/codecorn/littperl/perlsub.htm"