#PERL PROGRAMMING LANGUAGE INSTALL#
#PERL PROGRAMMING LANGUAGE CODE#
#PERL PROGRAMMING LANGUAGE PLUS#

To fix that bug before it becomes a problem, the next line adds 1 to the random number and prints the total as the die-roll result. That's fine for computers and programmers, but to most users, that's confusing, so it can be considered a bug. That means that a 6-sided die in this program can never roll a 6, but it can roll a 0. The roller subroutine or function, created with the sub keyword, uses the rand function of Perl to generate a pseudo-random number up to, and not including, the number provided as an argument. The die function gets triggered when no arguments are provided. Perl treats this as a stack and uses the shift function to assign it to the variable $sides. In this case, the expected argument is the desired side of a virtual die. The main part of the script begins by parsing the argument provided to the script when it is launched from a terminal.

#PERL PROGRAMMING LANGUAGE CODE#

The use strict setting tells Perl not to run the script when errors are found.īoth of these settings help you find errors in your code before they cause problems, so it's usually best to have them active in your scripts. The use warnings setting tells Perl to check for errors and issue warnings in the terminal about problems it finds. The next five lines are boilerplate includes and settings. The first line tells your POSIX terminal what executable to use to run the script. The syntax is similar to C or Java:ĭie ' You must provide a number of sides for the dice. The if statement is one of the most intuitive: Perl can test for a specific condition, and Perl decides how the program proceeds based on that condition. Most programs require a decision to be made, and those choices are defined and controlled by conditional statements and loops. These simple statements create a variable $var containing the strings 'Hello' and 'Perl' and then prints the contents of the variable to your terminal: $ perl -e '$var = 'hello perl' print ('$var ') ' Flow control Variable names in Perl are always preceded by a dollar sign ( $).

In Perl, you create variables by declaring a variable name and then its contents. Variables are how computers identify and track data. 'Find my phone and bring it to me' really means 'Find my phone and bring my phone to me.'įor computers, variables aren't a convenience but a necessity. For instance, the word 'it' can refer to any noun, so we use it as a convenient placeholder. Humans use variables every day without thinking about it. Python defines scope with whitespace, LISP uses parentheses, while C and Java use braces. Blocks are a useful organizational tool, but they also provide scope for data that you may only need to use for a small section of your program.

To try running your own Perl statement, open a terminal and type: $ perl -e 'print ('Hello Perl ') ' Perl blocksĪ block of Perl statements can be grouped together with braces ( ). Perl statementsĪ Perl statement is made up of expressions.

#PERL PROGRAMMING LANGUAGE PLUS#

The expression $a + $b contains variables (placeholders for data) and the plus symbol ( +), which is a math operator. The expression 2 returns the value of 2, and a returns the letter a.Įxpressions can be more complex.

The basic unit of Perl source code is an expression, which is anything that returns a value.įor instance, 1 is an expression.

#PERL PROGRAMMING LANGUAGE INSTALL#

On Windows, download and install it from the Perl website. On Linux and macOS, you already have Perl installed.

eBook: An introduction to programming with Bash.

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Perl programming language