PHPلغة PHP

The most popular server-side scripting language for creating dynamic web pages. PHP is open source and platform independent, and supports a large number of databases.

Returns the current type of its argument.

Takes a variable and its new type. Can result in loss of data: doubles are truncated when converted to integers.

Uses the number at the beginning of the string; if there is none, the string evaluates to 0.

e.g. (integer) $data — does not change the variable's content; it creates a temporary copy of its value.

Combines multiple strings.

Creates a named constant: the name and the value; an optional third boolean makes it case insensitive (constants are case sensitive by default). Assigning a value to a constant after it is declared is a syntax error.

An array with nonnumeric indices, created with => (index on the left, value on the right).

Sets the internal pointer to the first element.

Returns the index of the element currently referenced.

Moves the internal pointer to the next element.

Designed for iterating through arrays: the array, the keyword as, then two variables — the first gets the index, the second the value. With only one variable after as, it gets the value.

Compares two strings and returns -1 if the first alphabetically precedes the second, 0 if they are equal, 1 if the first follows the second.

A series of characters that serve as pattern-matching templates (search criteria) in strings, text files and databases.

Searches a string for a pattern (PCRE). The optional third argument stores the matches: element 0 = whole match, then each parenthetical part.

Beginning of a string; end of a string; any single character.

Match any single character from the list; ranges use a dash, e.g. [a-zA-Z].

Beginning / end of a word — matches whole words.

How often a character or set of characters can appear in a match.

Character classes are enclosed by [: and :]; inside another set of brackets they match all characters in the class.

Returns the modified string; used to remove matches before searching again.

Associative arrays predefined by PHP holding variables from user input, the environment or the web server, accessible in any variable scope. $_GET and $_POST hold data sent by HTTP get and post requests.

Escapes the normal meaning of a character in a string.

Terminates script execution; its optional string argument is printed as the script exits.

A piece of information stored by a server in a text file on a client's computer to maintain information about the client during and between browsing sessions. A server can access only the cookies it has placed.

No expiration → session cookie (until the browser closes); with expiration → persistent cookie. Only the name → the cookie is deleted. Must be called before any other output (sent with the HTTP header).

Superglobal array with all cookie values indexed by their names.

Determines whether the $_POST array contains keys for the form fields.

A variable variable: the value of the variable whose name equals the value of $variable.

Inserts a backslash (\) before any special characters in the passed string.