/ 
Perl-Tutorial-0.001
River stage zero No dependents
/ Perl::Tutorial::HelloWorld

NAME

Perl::Tutorial::HelloWorld - Hello World for Perl

SYNOPSIS


            

              
              
#!/usr/bin/perl
#
# The traditional first program.
# Strict and warnings are recommended.
use strict;
use warnings;
# Print a message.
print "Hello, World!\n";

DESCRIPTION

Running the program

Open a text editor, and type in the above program. Save it in a file named "hello". Then open a terminal window.

First ensure the file is given executable permissions:


            

              
              
chmod u+x hello

Then you can run the program using either of the following:


            

              
              
./hello
perl hello

You should see it print "Hello, World!" to the console.

The first line

Every Perl program should start with a line similar to one of these:


            

              
              
#!/usr/bin/perl
#!/usr/bin/env perl

or on Windows:


            

              
              
#!C:\Perl\bin\perl.exe
#!C:\strawberry\perl\bin\perl.exe

The first line is known as the "shebang line", and is used by UNIX-like systems to look up the path to the Perl interpreter.

Comments

Comments in Perl always start with a '#' character:


            

              
              
# This is a single-line comment.
# This comment extends over two lines
# to illustrate multi-line comments.
print 'hello'; # And here is an inline comment.

Anything to the right of a '#' will be ignored.

Statements

Statements always end with a semicolon in Perl:


            

              
              
print 'hello';
print 'This statement extends over two lines
because there is no semicolon on the first line.';

It is possible to have more than one statement on a single line, but generally this would not be very readable.

Strict and Warnings

These two statements turn on the 'strict' and 'warnings' pragmas:


            

              
              
use strict;
use warnings;

These are strongly encouraged for all Perl programs - they tell the Perl interpreter to check for programming errors like undeclared variables.

Printing to standard output

To print some output to the terminal, you can use the 'print' function:


            

              
              
print "Hello, World!\n";

In this case, the double-quoted string "Hello, World!\n" is being printed. You should see that the "\n" sequence does not appear on the console - it is used to mark the end of a line. Double-quoted strings can contain various other escape sequences.

SEE ALSO

Perl::Tutorial

COPYRIGHT AND LICENSING

Copyright (C) 2011 Copperly Ltd.

This documentation is free software; you can redistribute it and/or modify it under the same terms as Perl itself.