1. INTRODUCTION to PERL
PART 1

2. Background Practical Extraction and Report Language → Perl
Developed in 1987 by Larry Wall

3. SCALAR — The Basic Unit of Perl
Scalar = number or string
$scalar = “that’s me!”; # ‘$’ is used to declare scalars
Default value: “undef”
0 as a number
NULL as a string

4. SCALAR — The Basic Unit of Perl
$alice = 5;
$bob = “5”;
Dynamically typed
$alice == $bob # true
Can be accessed inside a string literal
print “What comes after 4? $alice”; # What comes after 4? 5

5. Operators Operators Assignment = Arithmetic + - * / String . x
Comparison == !=
<
>
<=
>= eq ne lt gt le ge

6. ASSIGNMENT OPERATOR
$var = “value”; # value

7. ARITHMETIC OPERATORS $var = 10 + 2; # 2 $var = 10 – 2; # 8

8. STRING OPERATORS $var = “Hello ” . “world!”; # Hello world!
$var = “Yeah! ” x 3; # Yeah! Yeah! Yeah!

9. NUMBER COMPARISON OPERATORS
$alice == $bob;
$alice != $bob;
$alice < $bob;
$alice > $bob;
$alice <= $bob;
$alice >= $bob;

10. STRING COMPARISON OPERATORS
$alice eq $bob;
$alice ne $bob;
$alice lt $bob;
$alice gt $bob;
$alice le $bob;
$alice ge $bob;

11. IF — CONTROL STRUCTURES
if (condition) { # code goes here! } else {

12. While — Control Structures
while (condition) { # code goes here! }

13. STANDARD INPUT
<STDIN>
$input = <STDIN>;

14. LISTS & Arrays List = collection of scalars
(“that’s”, “me!”); # lists are enclosed in parentheses
Array = variable that stores a list
@array = (“that’s”, “me!”); # arrays are declared with
Accessed with ‘$’ and ‘[]’
$item = $array[0]; # that’s