PHP

PHP is one of many interpreted languages written in C.

Development Environment

PHP CLI

Xochipilli says
Many Linux distributions package the PHP CLI separately

• php -l check syntax
• php -v version
• php -e oneliner

Variables and data types

PHP is a dynamically-typed language.

User-Defined Functions

Defining functions in PHP is accomplished using the function keyword, followed by the function name and comma delimited arguments, surrounded by parenthesis:

function myFunction(arg1, arg2) { ... }

If the function is encapsulated in an object, you may specify the visibility of the function, public, protected or private.

class MyClass { public function myFunction(arg1, arg2) { ... } ... }

Unlike some programming languages, like Perl or Python, PHP member functions implicitly extract their parent into the $this variable.

Security

• Type Handling
• XSS
• SQL Injection

Preventing SQL injection in PHP applications is relatively simple, so long as you are thorough. String input, surrounded by single quotes can be sanitized with mysql_real_escape_string(), which will escape dangerous characters such as single quotes (as well as \, so that you cannot escape the escapes!). Sanitizing integer input can be done simply by casting the input to int, like so:

$clean_int = (int)$dangerous_int;