Introducing php A Server Scripting Language

What Is php? 

Stands for PHP: Hypertext Processor 

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Recursive acronym

“a powerful tool for making dynamic and interactive Web pages.” –w3schools.com PHP runs on different platforms (Windows, Linux, Unix, Mac OS X, etc.) PHP is compatible with almost all servers used today (Apache, IIS, etc.) PHP has support for a wide range of databases PHP is free. Download it from the official PHP resource: www.php.net PHP is easy to learn and runs efficiently on the server side

What Can PHP Do? 

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PHP can generate dynamic page content PHP can create, open, read, write, and close files on the server PHP can collect form data PHP can send and receive cookies PHP can add, delete, modify data in your database PHP can restrict users to access some pages on your website PHP can encrypt data With PHP you are not limited to output HTML. You can output images, PDF files, and even Flash movies.You can also output any text, such as XHTML and XML.

How To Use php?  

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PHP files can contain text, HTML, JavaScript code, and PHP code PHP code are executed on the server, and the result is returned to the browser as plain HTML PHP files have a default file extension of ".php" Two parts 

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PHP source code HTML page with embedded PHP to display output

PHP Syntax The PHP script is executed on the server, and the plain HTML result is sent back to the browser.  The default file extension for PHP files is ".php".  A PHP file normally contains HTML tags, and some PHP scripting code.  A PHP script can be placed anywhere in the document.  A PHP script starts with : 

Embedded PHP Script Example

My first PHP page

More PHP Syntax 

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Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another. With PHP, there are two basic statements to output text in the browser: echo and print.

PHP Variables   

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Variables are "containers" for storing information: Example Much Like Algebra x=5 y=6 z=x+y In algebra we use letters (like x) to hold values (like 5). From the expression z=x+y above, we can calculate the value of z to be 11. In PHP these letters are called variables.

PHP Variables 

As with algebra, PHP variables can be used to hold values (x=5) or expressions (z=x+y).

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Variable can have short names (like x and y) or more descriptive names (age, carname, totalvolume).

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Rules for PHP variables:

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A variable starts with the $ sign, followed by the name of the variable A variable name must begin with a letter or the underscore character A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ ) A variable name should not contain spaces Variable names are case sensitive ($y and $Y are two different variables)

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Both PHP statements and PHP variables are case-sensitive.

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Creating (Declaring) PHP Variables 

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PHP has no command for declaring a variable. A variable is created the moment you first assign a value to it: $txt="Hello world!"; $x=5; After the execution of the statements above, the variable txt will hold the value Hello world!, and the variable x will hold the value 5. Note: When you assign a text value to a variable, put quotes around the value.

PHP Arrays An array stores multiple values in one single variable:  Example 

What is an Array?   

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An array is a special variable, which can hold more than one value at a time. If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this: $cars1="Saab"; $cars2="Volvo"; $cars3="BMW"; However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300? The solution is to use an array! An array can hold many values under a single name, and you can access the values by referring to an index number. In PHP, there are three types of arrays: Numeric array - Arrays with numeric index Associative array - Arrays with named keys Multidimensional array - An array containing one or more arrays

Associative Arrays Associative arrays are arrays that use named keys that you assign to them.  There are two ways to create an associative array: $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");  or: $age['Peter']="35"; $age['Ben']="37"; $age['Joe']="43";  The named keys can then be used in a script:  Example 

PHP foreach Loop The foreach loop is used to loop through arrays.  Syntax foreach ($array as $value) { code to be executed; } 

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For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.

PHP foreach Loop Example 

The following example demonstrates a loop that will print the values of the given array: 



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Output: one two three

PHP Built-In Functions 

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The real power of PHP comes from its functions. In PHP, there are more than 700 built-in functions. Examples: 

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fetch() Fetches the next row from a result set query($sql) Executes an SQL statement, returning a result set as a PDOStatement object

PHP Examples Download source code from online textbook website: www.sitepoint.com/books/phpmysql5/ 

PHP Source Code Example

Attribution 

http://www.w3schools.com/php/default.asp