lec 1what is php

8/4/2019 Lec 1What is PHP

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What is PHP?


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What is PHP?

PHP stands for PHP: Hypertext Preprocessor

PHP is a server-side scripting language, likeASP

PHP scripts are executed on the server

PHP supports many databases (MySQL,Informix, Oracle, Sybase, Solid, PostgreSQL,

Generic ODBC, etc.) PHP is an open source software

PHP is free to download and use


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What is a PHP File?

PHP files can contain text, HTML tags andscripts

PHP files are returned to the browser asplain HTML

PHP files have a file extension of ".php",".php3", or ".phtml"


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What is MySQL?

MySQL is a database server

MySQL is ideal for both small and largeapplications

MySQL supports standard SQL

MySQL compiles on a number of platforms

MySQL is free to download and use


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PHP + MySQL

PHP combined with MySQL are cross-platform (you can develop in Windows andserve on a Unix platform)


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Why PHP?

PHP runs on different platforms (Windows,Linux, Unix, etc.)

PHP is compatible with almost all serversused today (Apache, IIS, etc.)

PHP is FREE to download from the officialPHP resource: www.php.net

PHP is easy to learn and runs efficientlyon the server side
http://www.php.net/http://www.php.net/


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Where to Start?

To get access to a web server with PHPsupport, you can:

Install Apache (or IIS) on your own server,install PHP, and MySQL

Or find a web hosting plan with PHP andMySQL support


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What do you Need?

If your server supports PHP you don't need to doanything.

Just create some .php files in your webdirectory, and the server will parse them for you.

Because it is free, most web hosts offer PHPsupport.

However, if your server does not support PHP,you must install PHP.

Here is a link to a good tutorial from PHP.net onhow to install PHP5:http://www.php.net/manual/en/install.php
http://www.php.net/manual/en/install.phphttp://www.php.net/manual/en/install.php


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Basic PHP Syntax

Basic PHP Syntax A PHP scripting block always starts with . A PHP scripting block can be placedanywhere in the document.

On servers with shorthand support enabled you can starta scripting block with . For maximum compatibility, we recommend that you use

the standard form (


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Code Example

Each code line in PHP must end with a semicolon. The semicolon isa 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 tooutput the text "Hello World".


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Variables in PHP

Variables are used for storing a values, like textstrings, numbers or arrays.

When a variable is declared, it can be used over

and over again in your script. All variables in PHP start with a $ sign symbol.

The correct way of declaring a variable in PHP:

$var_name = value;

New PHP programmers often forget the $ sign atthe beginning of the variable. In that case it willnot work.


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Let's try creating a variable containing astring, and a variable containing a number:

In PHP, the variable is declared

automatically when you use it.


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Naming Rules for Variables

A variable name must start with a letter oran underscore "_"

A variable name can only contain alpha-numeric

characters and underscores (a-z, A-Z, 0-9, and _)

A variable name should not containspaces. If a variable name is more than

one word, it should be separated with anunderscore ($my_string), or withcapitalization ($myString)


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String Variables in PHP

String variables are used for values thatcontains characters.

After we create a string we can manipulateit. A string can be used directly in afunction or it can be stored in a variable.

Below, the PHP script assigns the text"Hello World" to a string variable called$txt:


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The Concatenation Operator

There is only one string operator in PHP.

The concatenation operator (.) is used to puttwo string values together.

To concatenate two string variables together,use the concatenation operator:


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The strlen() function

The strlen() function is used to returnthe length of a string.

Let's find the length of a string:


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The strpos() function

The strpos() function is used to search for characterwithin a string.

If a match is found, this function will return theposition of the first match. If no match is found, it

will return FALSE. Let's see if we can find the string "world" in our

string:

See Complete String Reference

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


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PHP Operators

PHP Operators


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PHP If...Else Statements

Conditional Statements

if statement - use this statement to execute somecode only if a specified condition is true

if...else statement - use this statement to executesome code if a condition is true and another code ifthe condition is false

if...elseif....else statement - use this statement toselect one of several blocks of code to be executed

switch statement - use this statement to select oneof many blocks of code to be executed


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The if Statement


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The if...else Statement


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The if...elseif....else Statement


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PHP Switch Statement


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PHP Arrays

A variable is a storage area holding a number ortext. The problem is, a variable will hold only onevalue.

An array is a special variable, which can store

multiple values in one single variable. If you have a list of items (a list of car names, for

example), storing the cars in single variablescould look like this:

$cars1="Saab";$cars2="Volvo";$cars3="BMW";


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In PHP, there are three kind of arrays

Numeric array - An array with a numericindex

Associative array - An array where each IDkey is associated with a value

Multidimensional array - An array containing

one or more arrays


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Numeric Arrays

A numeric array stores each array elementwith a numeric index.

There are two methods to create anumeric array.

In the following example the index areautomatically assigned (the index starts at 0):

$cars=array("Saab","Volvo","BMW","Toyota");


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In the following example we assign theindex manually:

$cars[0]="Saab";

$cars[1]="Volvo";$cars[2]="BMW";$cars[3]="Toyota";


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Associative Arrays

An associative array, each ID key isassociated with a value.

When storing data about specific namedvalues, a numerical array is not always thebest way to do it.

With associative arrays we can use the

values as keys and assign values to them.


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$ages = array("Peter"=>32,"Quagmire"=>30, "Joe"=>34);


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$ages['Peter'] = "32";$ages['Quagmire'] = "30";$ages['Joe'] = "34";


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Multidimensional Arrays

In a multidimensional array, each elementin the main array can also be an array.And each element in the sub-array can be

an array, and so on.


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$families = array("Griffin"=>array("Peter","Lois","Megan" ),

"Quagmire"=>array( "Glenn" ),"Brown"=>array("Cleve","Loret","Junior"));


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Array([Griffin] => Array([0] => Peter[1] => Lois[2] => Megan

)[Quagmire] => Array([0] => Glenn)

[Brown] => Array(

[0] => Cleveland[1] => Loretta[2] => Junior)

)


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Lets try displaying a single value from thearray above:

echo "Is " . $families['Griffin'][2] ." a part of the Griffin family?";

Is Megan a part of the Griffin family?


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PHP Looping - While Loops

PHP Loops while - loops through a block of code while a

specified condition is true

do...while - loops through a block of codeonce, and then repeats the loop as long as aspecified condition is true

for - loops through a block of code a specified

number of times foreach - loops through a block of code for

each element in an array


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While


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The do...while Statement


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The for Loop


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The foreach Loop


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PHP Functions

The real power of PHP comes from its functions.

In PHP, there are more than 700 built-infunctions.

To keep the script from being executed when thepage loads, you can put it into a function.

A function will be executed by a call to thefunction.

You may call a function from anywhere within apage.


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Create a PHP Function


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Thi d Ch1 d 2 D f


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This ends Ch1 and 2 Demos ofCh1 and 2 Covered.

Printing Example

Comments

Variables

Strings

Concatenation Operator

Numbers Tax Rate Example

Single And Double Quotation Marks

Array and if and Loops

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