mdst3705 2013-01-24-php2
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PHP 2
Prof AlvaradoMDST 3705
24 January 2013
Business• Reference materials posted• Use the principle of “TMI filtering”
– Filter out what has not been covered– Be comfortable with knowing a little
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
We live in “Barricell’s Universe”
A world that has emerged from the use of a a specific kind of
computer
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
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?”
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
Todays Exercises• Emulate the 10 PRINT program in PHP• Learn about arrays, control structures,
and functions • Riff on the model to produce other
outcomes
Resources• PHP
– Manual from PHP’s Home Page– PHP for Absolute Beginners
• HTML and CSS– W3Schools