CS 335/535 Web Programming - Week 6: Perl Programming

Chapter 13 - Perl and the Internet
- What is Perl? - Practical Extraction and Reporting Language
  Perl is an interpreted language optimized for scanning arbitrary text files, extracting information from those files, and printing reports based on that information.
  Perl combines the best features of C, sed, awk and sh.
- What are the Benefits of Perl?
  - Cost and Licensing (usually free)
  - Availability (most UNIX sites and NT Resource Kit)
  - Interpreted Language (fast development)
  - Language Capabilities (optimized for text processing)
  - Uses C libraries
  - Specialized Extensions to Perl for most database
  - TCP/IP Socket Capability
  - Easy to Learn
  - Has Built-in Debugging Facilities
  - Help is Readily Available - Perl language home page
  - Perl Examples are Readily Available CPAN ftp site
- What are the Negatives of Using Perl?
  - Interpreted Language - execution is not as fast
  - GNU CopyLeft License Agreement - can't distribute applications for sale
- What Can Perl Do?
  - CGI Scripts
  - Mail Processing
  - Automated Web Site Maintenance
  - Automating File Retrieval
- Is Perl for You?
The Perl Language
- About the Perl Chapters - man pages for Perl
- Writing Perl ScriptsHello World example
- Perl Data Types
  - Scalars [$a = "hello there";] simple I/O
  - Arrays of Scalars [@a = (2, 'hello there', 3.14);]printing a list
    copying and printing arrays
    Array Slice
    Sorting an array
  - Associative arrays of scalars ("hashes") [%stuff = (thing1, 'abcde', thing2, 'defgh', thing3, 'ijklm');] example of associative arrays
- Perl Line Oriented Formatting ex.
```
print <<EOF;
<HTML>
<HEAD>
	<TITLE>Untitled</TITLE>
<BODY>
..
</BODY>
</HTML>
EOF
     ;
```
- Predefined Variables - [see pp. 343-351]
- Perl Syntax - free-form language
- Perl Operators
  - arithmetic - +, -, *, /, **, % [conversion program]
  - arithmetic comparison <, >, ==, , <=, >=, !=, <=>
  - incrementation operator
  - string comparison lt, gt, eq, le, ge, ne, cmp
  - logical operators ||, &&, !, or, and, not, xor
  - bit manipulation &, |, ^, ~, <<, >>
  - string concatenation (.), repetition (x) [Concatenating Strings]
  - conditional operator [password checker]
  - matching operator
- Perl Built-in Functions [see pp. 359-389]
  - rand, srandDice simulation
  - Array Functions
- Perl Regular Expressions
- Perl Subroutines
  - Countdown Examples
  - Calculator