PERL

Basic of Perl

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1) Variable

Variable is a place to store a value, so we can refer to it or manipulate it throughout program. Perl has three types of variables; scalars, arrays and hases.

Scalar ($) 

Scalar variable stores a single (scalar) value. Perl scalar names are prefixed with a dollar sign ($), so for example, $x, $y, $z, $username, and $url are all examples of scalar variable names. A scalar can hold data of any type, be it a string, a number, or whatnot.

ex) 

$name = "Byeongeun Lee";

Array (@)

An array stores a list of values. While a scalar variable can only store one value, an array can store many. Perl array names are prefixed with an at-sign (@). In Perl, array indices start with 0, so to refer to the first element of the array @colors, you use $colors[0]. Note that when you're referring to a single element of an array, you prefix the name with a $ instead of the @. The $-sign again indicates that it's a single (scalar) value; the @-sign means you're talking about the entire array.

ex)

@Grades = ("A","B","C");

 

Hash (%)

A hash is a special kind of array - an associative array, or paired group of elements. Perl hash names are prefixed with a percent sign (%), and consist of pairs of elements - a key and a data value.

ex)

my %courses = (
    "Cell bio" => "prof.P",
    "Micro" => "prof.M",
);

 

Assignment study

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