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Published byAmber Davidson Modified over 9 years ago
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PHP PHP: Hypertext Preprocesor Personal Home Page Tools
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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
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Example......
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Basic Syntax statements terminated with ; comments: shell script style: #... (to end of line) C++ style: //... (to end of line) C style: /*... */
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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
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Arrays indexed: $a1 = array( “dog”, “cat”, “ant”, “mouse” ); $a1[2] = “snake”; associative: $a2 = array( 'bob'=>24, 'alice'=>33, 'ted'=>12 ); $a2['alice'] = 41;
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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
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Built-in Variables $_SERVER: associative array containing web server environment variables e.g. $_SERVER['GATEWAY_INTERFACE'] $_SERVER['REMOTE_ADDR'] $_SERVER['HTTP_ACCEPT']
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Built-in Variables $_GET: form fields submitted with GET $_POST: form fields submitted with POST
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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
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Built-in Variables $_REQUEST: everything from the $_GET, $_POST, and $_FILES variables
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Variable Scope unlike most languages global variables are not visible inside a funciton unless explicitly declared so$a = “hello”; function foo() {funtion foo() { print $a; // nothing !global $a; }print $a; // “hello” }
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Operators pretty much as in C/C++ no separate set of comparison operators for strings. operator for concatenating strings + operator for concatenating arrays
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Control Flow – if if ( $a > 2 ) {... } elseif ( $b < 10 ) {... } else {... }
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Control Flow – for, while, do... while for ( expr1; expr2; expr3 ) {... } while ( expr ) {... } do {... } while ( expr ); continue; break;
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foreach used with indexed or associative arrays foreach ( $array_var as $value ) {... } foreach ( $assoc_array as $key => $value ) {...}
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Funcitons funciton foo( $arg1, $arg2,..., $argn ) {... return $arg1 + $arg3; }... $a = foo( 1, 2, 3,... ); // $a gets 4
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Functions – default args funciton foo( $name, $weight = 27 ) {... echo $weight; }... foo( 'Bob', 33 ); // outputs 33 foo( 'Ted' ); // outputs 27 all default args should be rightmost in the args list
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Functions – reference args funciton foo( &$xyz ) {... $xyz = 'Carol'; }... $name = 'Alice'; foo( $name ); echo $name; // outputs 'Carol'
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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
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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
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mysql_connect $link = mysql_connect( $host, $user, $password ); returns a link identifier on success, FALSE on failure
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mysql_select_db mysql_select_db( $dbname, [ $link ] ); returns TRUE on success, FALSE on failure
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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
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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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3 Tier Architectures
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