The document discusses the PHP programming language, noting that it uses variables, values, expressions, and other constructs to model and create "worlds" through code, and introduces some basic PHP concepts like variables, arrays, control structures, functions, and sigils. Exercises are provided to emulate the 10 PRINT program in PHP and learn about arrays, control structures, and functions by riffing on the 10 PRINT model to produce other outcomes.

1. PHP 2
Prof Alvarado
MDST 3705
24 January 2013

2. Business
• Reference materials posted
• Use the principle of “TMI filtering”
– Filter out what has not been covered
– Be comfortable with knowing a little

3. Review
• Programming languages were invented so
that people could more easily control
computers
– Human like to interact with objects in the
world through language
• But like natural languages, programming
languages involve worlds
– Worlds are implied by code
– Worlds are modeled in code
– Worlds are created by code

5. We live in “Barricell’s Universe”
A world that has emerged from the
use of a a specific kind of computer

6. PHP as a language
• Variables
– Variables are like nouns
– Refer to locations in memory (pigeon holes)
• Values
– Values are like meanings
– Strings and numbers that are stored in
memory
• Expressions
– Expressions, e.g. $x + 1, are like clauses
– Expressions always “return” a value

7. Sentences
• Code is written in sentences called
“instructions”
Imperative and inquisitive modes
– Imperative
• $x = $y; // Like saying, “Let $x = $y”
• $x = 1 * 50 + $z;
– Inquisitive
• If ($x == 1) {} // Like asking, “Is $x equal to 1?”

8. Sigils
• $ as a prefix to variables
– Common in languages – Perl, Java,
JavaScript
– Useful mnemonic device – avoids “Hungarian
notation”
• Derives from medieval and renaissance
magic
– Sigil as a seal representing an angel or
demon – a “logo”
• Also used as a personal logo

9. Todays Exercises
• Emulate the 10 PRINT program in PHP
• Learn about arrays, control structures,
and functions
• Riff on the model to produce other
outcomes

10. Resources
• PHP
– Manual from PHP’s Home Page
– PHP for Absolute Beginners
• HTML and CSS
– W3Schools