PHP

1. PHP: Hypertext Preprocesor Personal Home Page Tools PHP

2. 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

3. Example ... <input type="submit" /> </form> <br /> <?php echo $a + $b ?> </body> </html> ...

4. <?php if ( $a ) { ?> <table border="1"> <?php for( $i=0; $i<$a; $i++ ) { ?> <tr><td> <?php echo $i ?> </td></tr> <?php } ?> </table> <?php } ?>

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

6. 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

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

8. 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

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

10. Built-in Variables • $_GET: • form fields submitted with GET • $_POST: • form fields submitted with POST

11. 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

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

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

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

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

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

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

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

19. 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

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

21. 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

22. Functions

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

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

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

26. 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

27. 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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