Web Site Design and Authoring

Web Site Design and Authoring Session 13 Scott Marino Scott Marino MSMIS Summer Session 1 - 2001

Topics • Introduction to PHP • PHP Syntax • Forms and Form Elements • Numbers and Strings • Conditionals and Loops • Arrays and Regular Expressions Scott Marino MSMIS Summer Session 1 - 2001

Introduction to PHP • Originally called Personal Home Page (PHP) • Now called Hypertext Preprocessor • Created in 1994 as an open source project • Server-Side execution • Cross Platform compatible • Unix, Windows, Mac, OS/2 • HTML embedded Scott Marino MSMIS Summer Session 1 - 2001

Why use PHP • Better, faster, and easier to learn than CGI, ASP, and JSP • PHP does much more than you can do with basic HTML • PHP was written specifically to create web pages • Perl, VBScript and Java were adapted to work on the web • Can’t do everything that other programming languages can Scott Marino MSMIS Summer Session 1 - 2001

Basic Syntax • <PHP? … ?> • Directive to PHP to interpret the code between the tags and perform the instructions • <PHP? phpinfo(); ?> • The phpinfo function prints installation information about PHP • Every instruction ends with a semicolon • Files are saved with a .php extension instead of .htm for Apache Scott Marino MSMIS Summer Session 1 - 2001

Basic Syntax • print(“Hello there”); • print(“<b>Hello there</b>”); • Print function to embed text or html into the web page • // or # denotes a single line comment • /* (several text lines) */ for commenting multiple lines Scott Marino MSMIS Summer Session 1 - 2001

Basic Syntax • Variable Types • Number • String • Array • $num_var = 1; • $float_num_var = 1.2; • $string_var = “PHP is cool!”; • Look at phpinfo(); for available environment variables Scott Marino MSMIS Summer Session 1 - 2001

Forms and PHP • PHP can access data elements from a form • Instead of calling a cgi script in the form action, the action will point to a PHP page • Can use both post and get methods • <input type=text name=lname> (on the form) • print(“$lname”); • Prints the PHP variable from the form field name Scott Marino MSMIS Summer Session 1 - 2001

Formatting Numbers • To print a $ sign, you must “escape” it • print (“total dollars = \$$total_dollars”); • The printf(); function can format numbers for printing • Supports mathematical precedence with the use of parenthesis • Has built in functions like round(); and abs(); • Can create random numbers with srand(); and rand(); Scott Marino MSMIS Summer Session 1 - 2001

String Formatting • trim(); removes leading and trailing spaces from string fields • ltrim(); and rtrim(); functions are available • $string = $astring . $bstring; • $string = $astring . “ “ . $bstring; • urlencode(); is used to convert characters to the proper format for a url • urldecode(); is used to convert an encoded url back to standard format Scott Marino MSMIS Summer Session 1 - 2001

String Formatting • strtok(); Creates a string from a token • $f_name = strtok($fullname, “ “); • substr($string,0,10); • Parses the first 10 characters of the contents of $string starting with position 0 • strlen($string); • Counts the number of characters in $string Scott Marino MSMIS Summer Session 1 - 2001

Conditionals • if (condition) {true action;} else {false action;} • If the condition or test results in “true” then execute the “true action” else execute the “false action” Scott Marino MSMIS Summer Session 1 - 2001

Conditionals • if (condition) {true action;} elseif (condition) {true action;} else {false action;} • The elseif allows for additional levels of conditions to be checked Scott Marino MSMIS Summer Session 1 - 2001

Conditionals • switch ($state) { case "AL": print ("Alabama"); break;….. default: print(”State of Confusion"); • Used for a longer list of conditions than is easily handled with elseif Scott Marino MSMIS Summer Session 1 - 2001

Looping • while (condition) {statements;} • do {statements;} while (condition); • for ($I = 1; $I <= somecount; $I++) {statements;} Scott Marino MSMIS Summer Session 1 - 2001

Arrays • $list = array(“apples”,”peaches”,”pears”); • Creates a simple array with elements in array positions 0,1, and 2 • $list = array(1=>“apples”, 2=>”peaches”, 3=>”pears”); • Creates an indexed array with elements in array positions 1, 2, and 3 • $list[] = “grapes”; • Adds element “grapes” to the end of the array Scott Marino MSMIS Summer Session 1 - 2001

Regular Expressions • PHP Supports Regular Expressions • ereg(“pattern”,”string”); • ereg is a case sensitive match • $pattern = “pattern”;$string = “string”;eregi($pattern, $string); • eregi is a case insensitive match Scott Marino MSMIS Summer Session 1 - 2001

Web Site Design and Authoring