1. An Introduction to Perl – Part I
Emily Goldberg
Perl, a compact Unix-type scripting language created in the 1980’s, is an easy to write language with multiple uses. The primary uses of Perl are administrative tasks and server-side scripting for web pages.

2. Scalar Data Scalar – holds one piece of data Numbers: Floating-Point
Integer
Non-decimal
-12
0377 octal
-2.7e32
3_814_524_705
0xff hex
0b binary
The basic unit of data is scalar data. Scalars can be numbers or strings. If a box is a container that holds one pair of shoes, then a crate is a container that holds multiple boxes. Similarly, scalar data (i.e.- strings, integers) hold one piece of data as opposed to a list which is a collection of scalars.

3. Scalar Data (cont’d.) Strings: Single-Quoted Double-Quoted
'hello\nthere'
hello\nthere
“hello\nthere”
hello
there
$string="world";
print "hi $string \n!";
hi world !

4. Variables Use $ prefix to denote a variable Ex.- $_points=5;
$name2=‘Larry’;
Variable names can contain letters, numbers, and underscores, but may NOT begin with a number.

5. Operators Number Operators Operation Operator Example Add + Subtract -
Multiply *
Divide /
Modulus %
10.5%3.2 = 1
Exponentiation **
2**3 = 8
Assign
=, *=. +=
Comparison
==, !=, <,>,<=,>=

6. Operators (cont’d.) String Operators Operation Operator Example
Concatenation .
"hello"."world"
helloworld
Repetition x
“hello”x3
hellohellohello
Comparison
eq, ne, lt, gt, le, ge
Assignment
=, *=. +=, .=
$name2.=‘ Lee’
larry Lee

7. Automatic Conversion Operations Results "hello“ . 3 * 5 “hello15"
“12” * “3” 36
"12fred34" * " 3"
12 - ”fred” 12

8. Standard Input/Output
Ex. - print "The answer is ", 6 * 7, ".\n";
Input
Ex. - $line=<STDIN>;
Remove “\n”- chomp($line);

9. Control Structures: if-else
if ($language eq “Perl”)
{ print “Always use curly braces!” ;}
else
{ print “ Who knows?!”;}

10. Control Structures: while
while(defined($line=<STDIN>))
{chomp($line);
print “This line was: $line \n”; }
while(<>)
{ chomp;
print “This line was: $_ \n”; }

11. Lists and Arrays A list is an ordered collection of scalars.
An array is a variable that contains a list.
A list with five elements

12. Lists and Arrays(cont’d.)
@numbers=(1,2,3,4);
@numbers=(1..4);
numbers[0]=‘one’;
print $numbers[$#numbers];
$a+3);

13. Questions?

14. Refrences
Learning Perl by Randal Schwartz and Tom Phoenix (Via Drexel Library electronic resources)
“Perl Basics” (