PHP PHP: Hypertext Preprocesor Personal Home Page Tools

Features scripting to generate dynamic content is embedded inside an XHTML page similar in syntax to Perl (sort of)‏ similar to server side inculdes:  web server parses.php file  executes scripts  sends result to client Built-in DB support

Example......

Basic Syntax statements terminated with ; comments:  shell script style: #... (to end of line)‏  C++ style: //... (to end of line)‏  C style: /*... */

Scalar Types boolean: true, false (case insensitive)‏ integer: usual decimal, octal and hex notations floating point: usual notations string:  single quote: 'xyz $abc': no variable interpolation  double quotes: “$abc xyz”: variable interpolation  heredoc: <<<END: multiline strings with varialbe interpolation

Arrays indexed: $a1 = array( “dog”, “cat”, “ant”, “mouse” ); $a1[2] = “snake”; associative: $a2 = array( 'bob'=>24, 'alice'=>33, 'ted'=>12 ); $a2['alice'] = 41;

Variables begin with a $ followed by the variable name variable variables: $xyz = 'abc'; $$xyz = 123; // actualy sets the value of $abc ! echo $abc; // prints out 123

Built-in Variables $_SERVER:  associative array containing web server environment variables  e.g. $_SERVER['GATEWAY_INTERFACE'] $_SERVER['REMOTE_ADDR'] $_SERVER['HTTP_ACCEPT']

Built-in Variables $_GET:  form fields submitted with GET $_POST:  form fields submitted with POST

Built-in Variables $_FILES:  form fields of the file type (uploaded files)‏ $_FILES['x']['name'] – name of the file on the client machine $_FILES['x']['type'] – mime type e.g. image/jpeg $_FILES['x']['size'] – file size in bytes $_FILES['x']['tmp_name'] – path specification to a local file containing the contents of the uploaded file

Built-in Variables $_REQUEST:  everything from the $_GET, $_POST, and $_FILES variables

Variable Scope unlike most languages global variables are not visible inside a funciton unless explicitly declared so$a = “hello”; function foo() {funtion foo() { print $a; // nothing !global $a; }print $a; // “hello” }

Operators pretty much as in C/C++ no separate set of comparison operators for strings. operator for concatenating strings + operator for concatenating arrays

Control Flow – if if ( $a > 2 ) {... } elseif ( $b < 10 ) {... } else {... }

Control Flow – for, while, do... while for ( expr1; expr2; expr3 ) {... } while ( expr ) {... } do {... } while ( expr ); continue; break;

foreach used with indexed or associative arrays foreach ( $array_var as $value ) {... } foreach ( $assoc_array as $key => $value ) {...}

Funcitons funciton foo( $arg1, $arg2,..., $argn )‏ {... return $arg1 + $arg3; }... $a = foo( 1, 2, 3,... ); // $a gets 4

Functions – default args funciton foo( $name, $weight = 27 )‏ {... echo $weight; }... foo( 'Bob', 33 ); // outputs 33 foo( 'Ted' ); // outputs 27 all default args should be rightmost in the args list

Functions – reference args funciton foo( &$xyz )‏ {... $xyz = 'Carol'; }... $name = 'Alice'; foo( $name ); echo $name; // outputs 'Carol'

Functions – reference returns $a = 7; $b = 3; funciton &foo( $x )‏ { global $a, $b; if ( $x ) return $a; else return $b; } $c =& foo( 1 ); // $c and $a the same $d =& foo( 0 ); // $d and $b the same

require textual inclusion require 'vars.php'; drops out of php mode into XHTML mode, so included file must have around any code require_once 'vars.php'  ensures a file is included only once per page

mysql_connect $link = mysql_connect( $host, $user, $password ); returns a link identifier on success, FALSE on failure

mysql_select_db mysql_select_db( $dbname, [ $link ] ); returns TRUE on success, FALSE on failure

mysql_query $result = mysql_query( $query, [ $link ] ); returns TRUE or a result set on success, FALSE on failure mysql_affected_rows( [ $link ] );  returns number of affected rows for non-SELECT queries mysql_num_rows( [ $link ] );  returns number of rows in result set for SELECT queries

mysql_fetch_* $iarray = mysql_fetch_row( $result ); fetches the next row in the result set as a regular indexed array $aarray = mysql_fetch_assoc( $result ); fetches the next row in the result set as an associative array

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