Perl Programming/First programs

A first taste of Perl

Here's a simple program written in Perl to get us started:

#!/usr/bin/perl

# Outputs Hello World to the screen.
 
print "Hello World!\n";

Let's take a look at this program line by line:

#!/usr/bin/perl

On Unix systems this tells the Operating System to execute this file with the program located at /usr/bin/perl. This is the default Unix location for the perl interpreter, on Windows #!C:\Perl\bin\perl.exe or #!C:\strawberry\perl\bin\perl.exe (depending on whether ActivePerl or Strawberry Perl was installed) should be used instead.

Shebang: A line at the start of a file, beginning with #!, that gives instructions to the operating system.

# Outputs ...

This line is a comment - it is ignored by the perl interpreter, but is very useful. It helps you to debug and maintain your code, and explain it to other programmers.

Comment: A line of plain text ignored by the interpreter in a file of code.

print "Hello World!\n";

The print instruction writes whatever follows it to the screen. The \n at the end of the string puts a new line to the screen. The semicolon at the end of the line tells the perl interpreter that the instruction is finished; you must put a semicolon at the end of every instruction in Perl code.

String: A sequence of characters used as data by a program.