Server Scripting Language -PHP

Server Scripting Language -PHP

• 1.
  Server-Side Scripting CIVE-IPT 2014Day 8 Presented by Deo Shao
• 2.
  Server-Side Scripting • Inorder to generate dynamic pages we use a server- side scripting language. • There are different types of server-side scripting languages such as PHP, ASP,ASP.NET, ColdFusion, JSP, Perl and others. • Each scripting languages is being interpreted by an application. • The application which interprets the server-side script is installed on the sever just like any other application. • PHP uses apache which comes with XAMPP & WAMP
• 3.
  Server-Side Scripting • Server-sidescripting languages are also operating systems dependent. • Each server-side scripting languages supports basic programming concepts such as variables, arrays, functions, loops, conditional statement and others. • They also contain more specific elements such as special objects, commands used to communicate with the server and a database and much more.
• 4.
  Server-Side Scripting • Whenthere is a need to store and retrieve information (user names, items in stock etc.) a database will be used to contain the data. • Sever-side script can communicate to a database using a structured query language (SQL) which manipulates the database (add, remove, update etc.) • More on that next week.
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  Three Tier Web Applications
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  PHP - HypertextPreprocessor In 1994 he created the PHP scripting language, authoring the first two versions of the language Some really large PHP websites • Facebook • Wikipedia • Flickr • Yahoo! Answers • Yahoo! Bookmarks • SourceForge • Photobucket • YouTube Rasmus Lerdorf (born 22 November 1968)
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  Basic PHP Syntax •You cannot view the PHP source code by selecting "View source" in the browser – you will only see the output from the PHP file, which is plain HTML. • This is because the scripts are executed on the server before the result is sent back to the browser. • A PHP scripting block always starts with <?php and ends with ?>. • A PHP scripting block can be placed anywhere in the document.
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  Basic PHP Syntax •On servers with shorthand support enabled you can start a scripting block with <? • and end with ?>. • However, for maximum compatibility, we recommend that you use the standard form (<?php) rather than the shorthand form. • A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.
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  Basic PHP Syntax •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. • There are two basic statements to output text with PHP: echo and print. In the • example above we have used the echo statement to output the text "Hello World".
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  PHP Variables • Variablesare used for storing a values, like text strings, numbers or arrays. • When a variable is set it can be used over and over again in your script • All variables in PHP start with a $ sign symbol. • The correct way of setting a variable in PHP: $var_name = value;
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  PHP Variables • InPHP a variable does not need to be declared before being set. • In the previous example, you see that you do not have to tell PHP which data type the variable is. • PHP automatically converts the variable to the correct data type, depending on how they are set. • In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it. • In PHP the variable is declared automatically when you use it.
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  PHP Variables • Avariable name must start with a letter or an underscore "_" • A variable name can only contain alpha-numeric characters and underscores (a-Z, 0-9, and _ ) • A variable name should not contain spaces. • If a variable name is more than one word, it should be separated with underscore ($my_string), or with capitalization ($myString)
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  Conditional Statements • Veryoften when you write code, you want to perform different actions for different decisions. • You can use conditional statements in your code to do this. If (condition) …code1 Else …code 2
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  The Switch Statement- Syntax • If you want to select one of many blocks of code to be executed, use the Switch statement. • The switch statement is used to avoid long blocks of if..elseif..else code.
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  The Switch Statement- Syntax switch (expression) { case label1: code to be executed if expression = label1; break; case label2: code to be executed if expression = label2; break; default: code to be executed if expression is different from both label1 and label2; }
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  The For loop-Syntax for(initialization; test_condition;loop_update) { statement(s) } • The test_condition uses relational and logical operators (<,>,>=,<, &&, ||, etc). • It is checked at the end of each iteration of the loop. • If the condition is still true then another iteration of the loop is undertaken
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  The While Loop-Syntax while (condition=TRUE) { statement(s) } • The lines of code within {} brackets are repeated as long as the condition specified in the while statement is TRUE. • The condition is checked BEFORE each iteration of the loop. • The actual condition can be a single condition or a logical combination of individual conditions (using logical operators - &&, || or !).
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  The Do WhileLoop - Syntax do { //statement(s); } while (condition=TRUE); • Statement(s) is/are executed, and condition is evaluated if the value of condition is TRUE, then control passes back to the beginning of the do statement, and the process repeats itself. • When condition is FALSE, then control passes to next statement bellow the loop block.