Introduction to PHP and Server Side Technology

Slide 2 PHP History Created in 1995 PHP 5.0 is the current version It’s been around since 2004

Slide 3 General PHP Characteristics (1) PHP is made up of a PHP scripting block PHP scripting blocks can appear anywhere in a Web page In addition to PHP scripting blocks, PHP documents typically contain HTML A page having embedded PHP script must have a file suffix of.php

Slide 4 General PHP Characteristics (2) Like ASP.NET PHP is server-side technology It runs on nearly all Web servers There is an IIS version It’s open source It talks to databases MySQL and others Facebook is a PHP application

Slide 5 General PHP Characteristics (2) PHP works with XML PHP supports AJAX PHP supports cookies

Slide 6 The Basics of PHP Syntax PHP scripts always appears between PHP statements always end in a semi-colon Comments have the same format as JavaScript PHP KEYWORDS ARE NOT CASE SENSITIVE BUT VARIABLE NAMES ARE

Slide 7 A First PHP Program As in

Slide 8 PHP Variables Like JavaScript, variables are ‘loosely typed’ Variables can be declared anywhere in a PHP script Variable names Must begin with a letter or underscore ‘_’ character The remaining characters can be letters, numbers or the underscore Variables cannot contain spaces

Slide 9 PHP Variables (Declaring) Variable declarations begin with the dollar sign ‘$’, followed by the variable name An equals sign and value follow the declaration Examples: $userName = “joe”; $pi = 3.14;

Slide 10 PHP Variables (Scope) Global variables are declared outside of a function Use the global keyword to access variables from a function Local variables are declared within a function Works the same way as JavaScript

Slide 11 Using Numeric Variables (1) Arithmetic operations work similarly in PHP and JavaScript Use print or echo to write output print returns 1 while echo returns nothing Use the $ to reference all variable names $x = 10; $y = 100; print $x + $y; /* 110 */

Slide 12 Using Numeric Variables (2) The following prints because the value is quoted $x = 10; $y = 100; print "$x + $y";

Slide 13 PHP Strings (Introduction) Strings work in PHP the same way they work in other languages There are several string functions: The dot (.) is the concatenation operator

Slide 14 PHP Data Types Similar to JavaScript

Slide 15 A First Server Round Trip Using Forms (1) Remember form widgets from JavaScript and so on Remember widgets are contained in a form Widgets are visible from PHP script so we can process their contents on the server

Slide 16 A First Server Round Trip Using Forms (2) The following form posts to the page named Welcome.php ( action attribute) Name: Age:

Slide 17 A First Server Round Trip Using Forms (3) Welcome.php contains the script to process the posted data Welcome ! You are years old.

Slide 18 A First Server Round Trip Using Forms (4)

Slide 19 GET and POST (Introduction) There are two basic ways to send data back to a Web server We call these HTTP verbs In all there are about 30 verbs Both GET and POST send data to Web servers

Slide 20 HTTP GET GET sends is data through the URL itself as a query string The URL looks something like this ?fname=zaphod&age=42 ?fname=zaphod&age=42 values appear after the ? Data appears as key=value pairs A & separates each key=value pair You don’t write the URL – HTTP does!

Slide 21 HTTP POST The request data does not appear inside the query string Data is sent in the HTTP header itself It’s possible to pull this data out of the header

Slide 22 HTTP GET and POST (Comparison) GET Query strings are small (100 characters) Posted data is visible It’s possible to bookmark the page PUT Large data blocks can be posted Posted data is hidden Page cannot be bookmarked

Slide 23 Reading Posted Data $_GET and $_POST retrieve data send to the server via a GET or POST, respectively They are built-in functions Pass the ID of the input control as an argument

Slide 24 Example Welcome ! You are years old.

Slide 25 PHP Functions (Introduction) PHP has built-in functions just like any language In all, there are about 700 so we will not get to all of them Refer to for a categorized list

Slide 26 PHP Functions (Syntax) It all looks just about like JavaScript (except the $ notation for variables) Functions and accept 0, 1 or many arguments Functions and return a value Again, the arguments are loosely typed

Slide 27 Declaring a PHP Function (Example) Declare a function named ShowFooter <?php function ShowFooter() { print(" "); print(“Rendered ". date("y-m-d")); print(" "); } ?>

Slide 28 Calling a Function (Example) Call the ShowFooter function shown previously