Notes 14 - Intro to PHP

Lecture Topics:

• php syntax
• running a php script via console
• accessing php script via browser HTTP request
• data types
• variables/identifiers
• scope
• operators
• constants
• conditional statments
• control structures
• looping
• embedding php in html
• understanding php output
• developer mode and errors
• logging
• print_r($var) and var_dump($var)

:~$php myScript.php

<?php // php opens here and closes here?>
<h1>HTML and PHP</h1>
<?php // php opens here again and closes here?>

$myVariable; // $[A..Za..z_][A..Za..z0..9_]+ case sensitive

DataTypes

• integer
• float
• string
• boolean
• array
• object
• resource

string gettype(var);   bool settype(var,'type');
is_int(), is_float(), is_string(), is_bool(), is_array(), is_object, is_null(), is_resource
bool isset(var [, var[,...]]);   void unset(var [, var[,...]]);   bool empty(var);

Scope

• Superglobals: global scope
• Constants: global scope
• Global Variables: global scope of script, and func **if declared
• Static Variables: local to function definition, retians value
• Function Variables: local to function, D.N.E(xists) after func

Superglobals: $_GET, $_POST, $GLOBALS, $_COOKIE, $_SESSION, $_FILE, $_ENV, $_REQUEST, $_SERVER

Operators

• Assignment: =
• Arithmetic: + - * / %
• Arithmetic Assignment: += -= *= /= %=
• String ops: .   .=
• ++increment decrement-- pre and post
• Comparison: < > <= >= == === != !== <>
• Logic: && AND, || OR, ! NOT, xor
• Ternary/Conditional: ?:

Control Structures

• if(expression) { ... }
• if(expression) { ... } else { ... }
• if(expression) { ... } elseif( expression) { ... } else { ... }
• switch($var) { case <int, float, char, string>: ... break; default: ... }

Looping

• while(expression) { ... }
• do { ... }while(expression);
• for(init; test; update) { ... }
• foreach($arr as $key => $val) { ... }