In Object-Oriented Programming a container called a class holds a collection of functions (called methods when they are in a class). A class does nothing until an instance of it is created (instantiated). Once an instance of a class has been created the methods can be used. A program can use any number of classes.
Scope The scope is the realm or dimension in which your variables and objects exist. All the things in this dimension must have their own unique name. Function and methods can define any number of variables Global Namespace This is the highest scope level PHP has. It contains the $_GLOBAL var for the PHP instance.
Define an array // Define an array. $my_array = [a,b,c,d]; // Define an array (the old standard way < php 5.3). $my_array = array(a,b,c,d); Get the last element of an array $lastEl = array_pop((array_slice($array, -1))); Count the number of element in an array $total = count($array);
DOMDocument PHP core comes with a very handy HTML parser called DOMDocument. Parse html DOM with DOMDocument // Create a new DOMDocument object. $dom = new DOMDocument; // Load the HTML page into the object. $dom->loadHTML($html); // Once the HTML is loaded into the object, access nodes and child elements: // Get an element by
Ternary Operators $var = 5; $var_is_greater_than_two = ($var > 2 ? true : false); // returns true. Alt Syntax (for views) PHP offers an alternative syntax for some of its control structures; namely, if, while, for, foreach, and switch. In each case, the basic form of the alternate syntax is to change the opening brace
filter_input // Sanitize input if (is_numeric($_POST[$post_key])) { $filtered_db_inputs[$post_key] = filter_input(INPUT_POST, $post_key, FILTER_SANITIZE_NUMBER_INT); } else { $filtered_db_inputs[$post_key] = filter_input(INPUT_POST, $post_key, FILTER_SANITIZE_STRING); } Trimming Use trim, ltrim, and rtrim to remove substrings from the beginning and end of a string. $string = ‘ _hello_ ‘; $trimmed = trim( $string ); // Returns “_hello_” echo trim( $trimmed, ‘_’
// Report all PHP errors. ini_set(‘display_errors’, 1); ini_set(‘display_startup_errors’, 1); error_reporting(E_ALL); This alone doesn’t make PHP show parse errors. The only way to show parse errors is to set display_errors = on in the php.ini file.
PHP’s falsey problem
A cheat-sheet with reminders, references and examples for working with PHP.