Perl Programming/First Programs
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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:
- 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.|
Hello your_name! How are you?
Remember: if you add another print instruction you will need to put a semicolon after it.