Web Technology - Overview of PHP Data Types and Concepts (Jntu-Anantapur)

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY KURNOOL

SUB: WEB TECHNOLOGIES (R09)

UNIT-3

Important Points about PHP:

PHP stands for PHP: Hypertext Preprocessor

PHP is a server-side scripting language that is embedded in HTML. It is used to manage dynamic content, databases, session tracking, even build entire e-commerce sites, like ASP

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

PHP supports a large number of major protocols such as POP3, IMAP, and LDAP. PHP4 added support for Java and distributed object architectures (COM and CORBA), making n-tier development a possibility for the first time.

What exactly PHP:

ü PHP files can contain text, HTML tags and scripts.

ü PHP files are returned to the browser as plain HTML

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

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

ü PHP is compatible with almost all servers used today (Apache, IIS, etc.)

ü PHP is case sensitive

Common uses of PHP:

· PHP performs system functions, i.e. from files on a system it can create, open, read, write, and close them.

· PHP can handle forms, i.e. gather data from files, save data to a file, thru email you can send data, return data to the user.

· You add, delete, and modify elements within your database thru PHP.

· Access cookies variables and set cookies.

· Using PHP, you can restrict users to access some pages of your website.

· It can encrypt data.

Characteristics of PHP

Five important characteristics make PHP's practical nature possible:

1. Simplicity

2. Efficiency

3. Security

4. Flexibility

5. Familiarity

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PHP Installation:

ü Download PHP for free here: http://www.php.net/downloads.php

PHP Environment Setup

In order to develop and run PHP Web pages three vital components need to be installed on your computer system.

Web Server - PHP will work with virtually all Web Server software, including Microsoft's Internet Information Server (IIS) but then most often used is freely availble Apache Server. Download Apache for free here: http://httpd.apache.org/download.cgi

Database - PHP will work with virtually all database software, including Oracle and Sybase but most commonly used is freely available MySQL database. Download MySQL for free here: http://www.mysql.com/downloads/index.html

PHP Parser - In order to process PHP script instructions a parser must be installed to generate HTML output that can be sent to the Web Browser.

Apache Configuration for PHP

Apache uses httpd.conf file for global settings, and the .htaccess file for per-directory access settings. Older versions of Apache split up httpd.conf into three files (access.conf, httpd.conf, and srm.conf), and some users still prefer this arrangement.

Apache server has a very powerful, but slightly complex, configuration system of its own. Learn more about it at the Apache Web site: www.apache.org

The following section describe settings in httpd.conf that affect PHP directly and cannot be set elsewhere. If you have standard installation then httpd.conf will be found at /etc/httpd/conf:

Timeout

This value sets the default number of seconds before any HTTP request will time out. If you set PHP's max_execution_time to longer than this value, PHP will keep grinding away but the user may see a 404 error. In safe mode, this value will be ignored; you must use the timeout value in php.ini instead

DocumentRoot

DocumentRoot designates the root directory for all HTTP processes on that server. It looks something like this on Unix:

DocumentRoot ./usr/local/apache_1.3.6/htdocs.

You can choose any directory as document root.

AddType

The PHP MIME type needs to be set here for PHP files to be parsed. Remember that you can associate any file extension with PHP like .php3, .php5 or .htm.

AddType application/x-httpd-php .php AddType application/x-httpd-phps .phps AddType application/x-httpd-php3 .php3 .phtml AddType application/x-httpd-php .html

Action

You must uncomment this line for the Windows apxs module version of Apache with shared object support:

LoadModule php4_module modules/php4apache.dll

or on Unix flavors:

LoadModule php4_module modules/mod_php.so

AddModule

You must uncomment this line for the static module version of Apache.

AddModule mod_php4.c

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PHP Syntax:

Note:

PHP code is executed on the server, and the plain HTML result is sent 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.

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

The file must have a .php extension

PHP tags can be represented in 4 ways

1. Canonical PHP tags:

Eg: <?php...... ?>

2. Short-open (SGML-style) tags:

                            Eg: <?...?>

3. ASP-style tags:

Eg: <%...%>

4. HTML script tags:

Eg : <script language="PHP">...</script>

Comment Lines in PHP:

Note: Comment lines are used in the program to understand the code

There are two commenting formats in PHP:

1. Single-line comments(# or //)



2. Multi-lines comments(/*----*/)

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PHP Variables:

A variable is used to store information.

Variables are used for storing values, like text strings, 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: Eg: $var_name = value;

Eg: creating a variable containing a string, and a variable containing a number:

<?php $txt="HelloWorld!"; $x=16; ?>

PHP is a Loosely Typed Language:

In PHP, a variable does not need to be declared before adding a value to it.

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 its value.

Naming Rules for Variables

A variable name must start with a letter or an underscore "_"

A variable name can only contain alpha-numeric characters and underscores (a-z, 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 an underscore ($my_string), or with capitalization ($myString)

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PHP String Variables: A string variable is used to store and manipulate text.

String Variables in PHP:

String variables are used for values that contain characters.

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

Eg: <?php

$txt="Hello World";


echo $txt;


?>

The output of the code above will be:

Hello World

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PHP data types:

A data type refers to the type of data a variable can store. PHP has eight (8) different data types you can work with. These are:

PHP has eight data types:

Scalar types

• boolean



• integer



• float



• string

Compound types

• array



• object

Special types

• resources



• NULL

Boolean values:

In PHP the boolean data type is a primitive data type having one of two values: True or False. This is a fundamental data type.

<?php   $male = False;   $r = rand(0, 1);   $male = $r ? True: False;   if ($male) {     echo "We will use name John\n"; } else {     echo "We will use name Victoria\n"; } ?>

The script uses a random integer generator to simulate our case.

$r = rand(0, 1);

The rand() function returns a random number from the given integer boundaries. In our case 0 or 1.

$male = $r ? True: False;

We use the ternary operator to set a $male variable. The variable is based on the random $r value. If $r equals to 1, the $male variable is set to True. If $r equals to 0, the $male variable is set to False.

if ($male) {

echo "We will use name John\n";

} else {

echo "We will use name Victoria\n";

}

We print the name. The if command works with boolean values. If the variable $male is True, we print the "We will use name John" to the console. If it has a False value, we print the other string.

The following script shows some common values that are considered to be True or False. For example, empty string, empty array, 0 are considered to be False.

<?php

class Object {};

var_dump((bool) "");

var_dump((bool) 0);

var_dump((bool) -1);

var_dump((bool) "PHP");

var_dump((bool) array(32));

var_dump((bool) array());

var_dump((bool) "false");

var_dump((bool) new Object());

var_dump((bool) NULL);

?>

In this script, we inspect some values in a boolean context. The var_dump()function shows information about a variable. The (bool) construct is called casting. In its casual context, the 0 value is a number. In a boolean context, it is False. The boolean context is when we use (bool) casting, when we use certain operators (negation, comparison operators) and when we use if/else, while keywords.

$ php boolean.php

bool(false)

bool(false)

bool(true)

bool(true)

bool(true)

bool(false)

bool(true)

bool(true)

bool(false)

Here is the outcome of the script.

Integers

Integers are a subset of the real numbers. They are written without a fraction or a decimal component. Integers fall within a set Z = {..., -2, -1, 0, 1, 2, ...} Integers are infinite.

In computer languages, integers are primitive data types. Computers can practically work only with a subset of integer values, because computers have finite capacity. Integers are used to count discrete entities. We can have 3, 4, 6 humans, but we cannot have 3.33 humans. We can have 3.33 kilograms.

Integers can be specified in three different notations in PHP. Decimal, hexadecimal and octal. Octal values are preceded by 0, hexadecimal by 0x.

<?php

$var1 = 31;

$var2 = 031;

$var3 = 0x31;

echo "$var1\n";

echo "$var2\n";

echo "$var3\n";

?>

We assign 31 to three variables using three notations. And we print them to the console.

$ php notation.php

31

25

49

The default notation is the decimal. The script shows these three numbers in decimal.

Integers in PHP have a fixed maximum size. The size of integers is platform dependent. PHP has built-in constants to show the maximum size of an integer.

$ uname -mo

i686 GNU/Linux

$ php -a

Interactive shell

php > echo PHP_INT_SIZE;

4

php > echo PHP_INT_MAX;

2147483647

php >

On my 32bit Ubuntu system, an integer value size is four bytes. The maximum integer value is 2147483647.

In Java and C, if an integer value is bigger than the maximum value allowed, integer overflow happens. PHP works differently. In PHP, the integer becomes a float number. Floating point numbers have greater boundaries.

<?php

$var = PHP_INT_MAX;

echo var_dump($var);

$var++;

echo var_dump($var);

?>

We assign a maximum integer value to the $var variable. We increase the variable by one. And we compare the contents.

$ php boundary.php

int(2147483647)

float(2147483648)

As we have mentioned previously, internally, the number becomes a floating point value.

In Java, the value after increasing would be -2147483648. This is where the term integer overflow comes from. The number goes over the top and becomes the smallest negative integer value assignable to a variable.

If we work with integers, we deal with discrete entities. We would use integers to count apples.

<?php

# number of baskets

$baskets = 16;

# number of apples in each basket

$apples_in_basket = 24;

# total number of apples

$total = $baskets * $apples_in_basket;

echo "There are total of $total apples \n";

?>

In our script, we count the total amount of apples. We use the multiplication operation.

$ php apples.php

There are total of 384 apples

Floating point numbers

Floating point numbers represent real numbers in computing. Real numbers measure continuous quantities. Like weight, height or speed. Floating point numbers in PHP can be larger than integers and they can have a decimal point. The size of a float is platform dependent.

We can use various syntax to create floating point values.

<?php

$a = 1.245;

$b = 1.2e3;

$c = 2E-10;

$d = 1264275425335735;

var_dump($a);

var_dump($b);

var_dump($c);

var_dump($d);

?>

In this example, we have two cases of notations, that are used by scientists to denote floating point values. Also the $d variable is assigned a large number, so it is automatically converted to float type.

$ php floats.php

float(1.245)

float(1200)

float(2.0E-10)

float(1264275425340000)

This is the output of the above script.

According to the documentation, floating point numbers should not be tested for equality. We will show an example why.

$ php -a

Interactive shell

php > echo 1/3;

0.333333333333

php > $var = (0.333333333333 == 1/3);

php > var_dump($var);

bool(false)

php >

In this example, we compare two values that seem to be identical. But they yield unexpected result.

Let's say a sprinter for 100m ran 9.87s. What is his speed in km/h?

<?php

# 100m is 0.1 km

$distance = 0.1;

# 9.87s is 9.87/60*60 h

$time = 9.87 / 3600;

$speed = $distance / $time;

echo "The average speed of a sprinter is $speed \n";

?>

ü In this example, it is necessary to use floating point values.

$speed = $distance / $time;

ü To get the speed, we divide the distance by the time.

$ php sprinter.php

The average speed of a sprinter is 36.4741641337

This is the output of the sprinter script. 36.4741641337 is a floating point number.

Strings

ü String is a data type representing textual data in computer programs. Probably the single most important data type in programming.

ü Since string are very important in every programming language, we will dedicate a whole chapter to them. Here we only drop a small example.

<?php

$a = "PHP ";

$b = 'PERL';

echo $a, $b;

echo "\n";

?>

ü We can use single quotes and double quotes to create string literals.

$ php strings.php

PHP PERL

ü The script outputs two strings to the console. The \n is a special sequence, a new line. The effect of this character is like if you hit the enter key when typing text.

Arrays

ü Array is a complex data type which handles a collection of elements. Each of the elements can be accessed by an index. In PHP, arrays are more diverse. Arrays can be treated as arrays, lists or dictionaries. In other words, arrays are all what in other languages we call arrays, lists, dictionaries.

ü Because collections are very important in all computer languages, we dedicate two chapters to collections - arrays. Here we show only a small example.

<?php

$names = array("Jane", "Lucy", "Timea", "Beky", "Lenka");

print_r($names);

?>

The array keyword is used to create a collection of elements. In our case we have names. The print_r function prints a human readable information about a variable to the console.

$ php init.php

Array

(

[0] => Jane

[1] => Lucy

[2] => Timea

[3] => Beky

[4] => Lenka

)

Output of the script. The numbers are indeces by which we can access the names.

Objects

So far, we have been talking about built-in data types. Objects are user defined data types. Programmers can create their data types that fit their domain. More about objects in chapter about object oriented programming, OOP.

Resources

Resources are special data types. They hold a reference to an external resource. They are created by special functions. Resources are handlers to opened files, database connections or image canvas areas.

NULL

There is another special data type - NULL. Basically, the data type means non existent, not known or empty.

In PHP, a variable is NULL in three cases:

• it was not assigned a value



• it was assigned a special NULL constant



• it was unset with the unset() function

<?php

$a;

$b = NULL;

$c = 1;

unset($c);

$d = 2;

if (is_null($a)) echo "\$a is null\n";

if (is_null($b)) echo "\$b is null\n";

if (is_null($c)) echo "\$c is null\n";

if (is_null($d)) echo "\$d is null\n";

?>

ü In our example, we have four variables. Three of them are considered to be NULL. We use the is_null() function to determine, if the variable is NULL.

$ php null.php

$a is null

$b is null

$c is null

The Concatenation Operator

ü There is only one string operator in PHP.

ü The concatenation operator (.)  is used to put two string values together.

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

<?php $txt1="Hello World!"; $txt2="What a nice day!"; echo $txt1 . " " . $txt2; ?>

The output of the code above will be: Hello World! What a nice day!

The strlen() function:

ü The strlen() function is used to return the length of a string.

Let's find the length of a string:

Eg: <?php

echo strlen("Hello world!");


?>

The output of the code above will be: 12

The strpos() function:

ü The strpos() function is used to search for a character/text within a string.

Let's see if we can find the string "world" in our string:

Eg: <?php

echo strpos("Hello world!","world");


?>

The output of the code above will be: 6(position starts with ZERO)

Note: if match is found then it return character position other wise returns FALSE

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PHP Operators:

PHP Operators

This section lists the different operators used in PHP.

Arithmetic Operators

Operator	Description	Example	Result
+	Addition	x=2 x+2	4
-	Subtraction	x=2 5-x	3
*	Multiplication	x=4 x*5	20
/	Division	15/5 5/2	3 2.5
%	Modulus (division remainder)	5%2 10%8 10%2	1 2 0
++	Increment	x=5 x++	x=6
--	Decrement	x=5 x--	x=4

Assignment Operators

Operator	Example	Is The Same As
=	x=y	x=y
+=	x+=y	x=x+y
-=	x-=y	x=x-y
*=	x*=y	x=x*y
/=	x/=y	x=x/y
.=	x.=y	x=x.y
%=	x%=y	x=x%y

Comparison Operators

Operator	Description	Example
==	is equal to	5==8 returns false
!=	is not equal	5!=8 returns true
<>	is not equal	5<>8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

Logical Operators

Operator	Description	Example
&&	and	x=6 y=3 (x < 10 && y > 1) returns true
||	or	x=6 y=3 (x==5 || y==5) returns false
!	not	x=6 y=3 !(x==y) returns true

Conditional operators:

Operator	Description	Example
? :	Conditional Expression	If Condition is true ? Then value X : Otherwise value Y

PHP supports following three decision making statements:

• if...else statement - use this statement if you want to execute a set of code when a condition is true and another if the condition is not true



• elseif statement - is used with the if...else statement to execute a set of code if one of several condition are true



• switch statement - is used 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.

The If...Else Statement

If you want to execute some code if a condition is true and another code if a condition is false, use the if....else statement.

Syntax

if (condition)   code to be executed if condition is true; else   code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":

<html> <body> <?php $d=date("D"); if ($d=="Fri")   echo "Have a nice weekend!"; else   echo "Have a nice day!"; ?> </body>   </html>

If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:

<html>   <body> <?php $d=date("D"); if ($d=="Fri")   {   echo "Hello!<br />";   echo "Have a nice weekend!";   echo "See you on Monday!";   } ?> </body> </html>

The ElseIf Statement

If you want to execute some code if one of several conditions are true use the elseif statement

Syntax

if (condition)   code to be executed if condition is true; elseif (condition)   code to be executed if condition is true; else   code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":

<html> <body> <?php $d=date("D"); if ($d=="Fri")   echo "Have a nice weekend!"; elseif ($d=="Sun")   echo "Have a nice Sunday!"; else   echo "Have a nice day!"; ?> </body> </html>

The Switch Statement

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.

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;   }

Example

The switch statement works in an unusual way. First it evaluates given expression then seeks a lable to match the resulting value. If a matching value is found then the code associated with the matching label will be executed or if none of the lables match then statement will will execute any specified default code.

<html> <body> <?php $d=date("D"); switch ($d) { case "Mon":   echo "Today is Monday";   break; case "Tue":   echo "Today is Tuesday";   break; case "Wed":   echo "Today is Wednesday";   break; case "Thu":   echo "Today is Thursday";   break; case "Fri":   echo "Today is Friday";   break; case "Sat":   echo "Today is Saturday";   break; case "Sun":   echo "Today is Sunday";   break; default:   echo "Wonder which day is this ?"; } ?> </body> </html>

PHP supports following four loop types.

• for - loops through a block of code a specified number of times.



• while - loops through a block of code if and as long as a specified condition is true.



• do...while - loops through a block of code once, and then repeats the loop as long as a special condition is trur.



• foreach - loops through a block of code for each element in an array.

We will discuss about continue and break keywords used to control the loops execution.

The for loop statement

The for statement is used when you know how many times you want to execute a statement or a block of statements.

Syntax

for (initialization; condition; increment) {   code to be executed; }

The initializer is used to set the start value for the counter of the number of loop iterations. A variable may be declared here for this purpose and it is tradional to name it $i.

Example

The following example makes five iterations and changes the assigned value of two variables on each pass of the loop:

<html> <body> <?php $a = 0; $b = 0;   for( $i=0; $i<5; $i++ ) {     $a += 10;     $b += 5; } echo ("At the end of the loop a=$a and b=$b" ); ?> </body> </html>

This will produce following result:

At the end of the loop a=50 and b=25

The while loop statement

The while statement will execute a block of code if and as long as a test expression is true.

If the test expression is true then the code block will be executed. After the code has executed the test expression will again be evaluated and the loop will continue until the test expression is found to be false.

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Syntax

while (condition) {     code to be executed; }

Example

This example decrements a variable value on each iteration of the loop and the counter increments until it reaches 10 when the evaluation is false and the loop ends.

<html> <body> <?php $i = 0; $num = 50;   while( $i < 10) {    $num--;    $i++; } echo ("Loop stopped at i = $i and num = $num" ); ?> </body> </html>

This will produce following result:

Loop stopped at i = 1 and num = 40

The do...while loop statement

The do...while statement will execute a block of code at least once - it then will repeat the loop as long as a condition is true.

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Syntax

do {    code to be executed; }while (condition);

Example

The following example will increment the value of i at least once, and it will continue incrementing the variable i as long as it has a value of less than 10:

<html> <body> <?php $i = 0; $num = 0; do {   $i++; }while( $i < 10 ); echo ("Loop stopped at i = $i" ); ?> </body> </html>

This will produce following result:

Loop stopped at i = 10

The foreach loop statement

The foreach statement is used to loop through arrays. For each pass the the value of the current array element is assigned to $value and the array pointer is moved by one and in the next pass next element will be processed.

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Syntax

foreach (array as value) {     code to be executed;   }

Example

Try out following example to list out the values of an array.

<html> <body> <?php $array = array( 1, 2, 3, 4, 5); foreach( $array as $value ) {   echo "Value is $value <br />"; } ?> </body> </html>

This will produce following result:

Value is 1 Value is 2 Value is 3 Value is 4 Value is 5

The break statement

The PHP break keyword is used to terminate the execution of a loop prematurely.

The break statement is situated inside the statement block. If gives you full control and whenever you want to exit from the loop you can come out. After coming out of a loop immediate statement to the loop will be executed.

Example

In the following example condition test becomes true when the counter value reaches 3 and loop terminates.

<html> <body>   <?php $i = 0;   while( $i < 10) {    $i++;    if( $i == 3 )break; } echo ("Loop stopped at i = $i" ); ?> </body> </html>

This will produce following result:

Loop stopped at i = 3

The continue statement

The PHP continue keyword is used to halt the current iteration of a loop but it does not terminate the loop.

Just like the break statement the continue statement is situated inside the statement blokc containing the code that the loop executes, preceded by a conditional test. For the pass encountering continue statement, rest of the loop code is skipped and next pass starts.

Example

In the following example loop prints the value of array but for which condition bceoms true it just skip the code and next valuye is printed.

<html> <body> <?php $array = array( 1, 2, 3, 4, 5); foreach( $array as $value ) {   if( $value == 3 )continue;   echo "Value is $value <br />"; } ?> </body> </html>

This will produce following result

Value is 1 Value is 2 Value is 4 Value is 5

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PHP Arrays:

ü An array stores multiple values in one single variable.

ü A variable is a storage area holding a number or text. The problem is, a variable will hold only one value.

ü 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 variables could look like this:

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

ü 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?

ü The best solution here is to use an array!

ü An array can hold all your variable values under a single name. And you can access the values by referring to the array name.

ü Each element in the array has its own index so that it can be easily accessed.

In PHP, there are three kind of arrays:

• Numeric array - An array with a numeric index



• Associative array - An array where each ID key is associated with a value



• Multidimensional array - An array containing one or more arrays

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Numeric Arrays

ü A numeric array stores each array element with a numeric index.

ü There are two methods to create a numeric array.

1. In the following example the index are automatically assigned (the index starts at 0):

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

2. In the following example we assign the index manually:

$cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota";

Example

In the following example you access the variable values by referring to the array name and index:

<?php $cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota"; echo $cars[0] . " and " . $cars[1] . " are Swedish cars."; ?>

The code above will output:

Saab and Volvo are Swedish cars.

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Associative Arrays

An associative array, each ID key is associated with a value.

When storing data about specific named values, a numerical array is not always the best way to do it.

With associative arrays we can use the values as keys and assign values to them.

Example 1

In this example we use an array to assign ages to the different persons:

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

Example 2

This example is the same as example 1, but shows a different way of creating the array:

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

The ID keys can be used in a script:

<?php $ages['Peter'] = "32"; $ages['Quagmire'] = "30"; $ages['Joe'] = "34"; echo "Peter is " . $ages['Peter'] . " years old."; ?>

The code above will output:

Peter is 32 years old.

---

Multidimensional Arrays

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

Example

In this example we create a multidimensional array, with automatically assigned ID keys:

$families = array   (   "Griffin"=>array   (   "Peter",   "Lois",   "Megan"   ),   "Quagmire"=>array   (   "Glenn"   ),   "Brown"=>array   (   "Cleveland",   "Loretta",   "Junior"   )   );

The array above would look like this if written to the output:

Array ( [Griffin] => Array   (   [0] => Peter   [1] => Lois   [2] => Megan   ) [Quagmire] => Array   (   [0] => Glenn   ) [Brown] => Array   (   [0] => Cleveland   [1] => Loretta   [2] => Junior   ) )

Example 2

Lets try displaying a single value from the array above:

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

The code above will output:

Is Megan a part of the Griffin family?

---

PHP Strings:

ü They are sequences of characters, like "PHP supports string operations".

Following are valid examples of string

$string_1 = "This is a string in double quotes"; $string_2 = "This is a somewhat longer, singly quoted string"; $string_39 = "This string has thirty-nine characters"; $string_0 = ""; // a string with zero characters

ü Singly quoted strings are treated almost literally, whereas doubly quoted strings replace variables with their values as well as specially interpreting certain character sequences.

<? $variable = "name"; $literally = 'My $variable will not print!\\n'; print($literally); $literally = "My $variable will print!\\n"; print($literally); ?>

This will produce following result:

My $variable will not print!\n My name will print

There are no artificial limits on string length - within the bounds of available memory, you ought to be able to make arbitrarily long strings.

Strings that are delimited by double quotes (as in "this") are preprocessed in both the following two ways by PHP:

• Certain character sequences beginning with backslash (\) are replaced with special characters



• Variable names (starting with $) are replaced with string representations of their values.

The escape-sequence replacements are:

• \n is replaced by the newline character



• \r is replaced by the carriage-return character



• \t is replaced by the tab character



• \$ is replaced by the dollar sign itself ($)



• \" is replaced by a single double-quote (")



• \\ is replaced by a single backslash (\)

String Concatenation Operator

To concatenate two string variables together, use the dot (.) operator:

<?php $string1="Hello World"; $string2="1234"; echo $string1 . " " . $string2; ?>

This will produce following result:

Hello World 1234

If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string.

Between the two string variables we added a string with a single character, an empty space, to separate the two variables.

---

Using the strlen() function

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

Let's find the length of our string "Hello world!":

<?php echo strlen("Hello world!"); ?>

This will produce following result:

12

The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string)

Using the strpos() function

The strpos() function is used to search for a string or character within a string.

If a match is found in the string, this function will return the position 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:

<?php echo strpos("Hello world!","world"); ?>

This will produce following result:

6

As you see the position of the string "world" in our string is position 6. The reason that it is 6, and not 7, is that the first position in the string is 0, and not 1.

---

PHP Functions:

ü The real power of PHP comes from its functions.

ü In PHP, there are more than 700 built-in functions.

A function is a piece of code which takes one more input in the form of parameter and does some processing and returns a value.

You already have seen many functions like fopen() and fread() etc. They are built-in functions but PHP gives you option to create your own functions as well.

There are two parts which should be clear to you:

• Creating a PHP Function



• Calling a PHP Function

In fact you hardly need to create your own PHP function because there are already more than 1000 of built-in library functions created for different area and you just need to call them according to your requirement.

Please refer to PHP Function Reference for a complete set of useful functions.

Creating PHP Function:

Its very easy to create your own PHP function. Suppose you want to create a PHP function which will simply write a simple message on your browser when you will call it. Following example creates a function called writeMessage() and then calls it just after creating it.

Note that while creating a function its name should start with keyword function and all the PHP code should be put inside { and } braces as shown in the following example below:

<html> <head> <title>Writing PHP Function</title> </head> <body> <?php /* Defining a PHP Function */ function writeMessage() { echo "You are really a nice person, Have a nice time!"; } /* Calling a PHP Function */ writeMessage(); ?> </body> </html>

This will display following result:

You are really a nice person, Have a nice time!

PHP Functions with Paramters:

PHP gives you option to pass your parameters inside a function. You can pass as many as parameters your like. These parameters work like variables inside your function. Following example takes two integer parameters and add them together and then print them.

<html> <head> <title>Writing PHP Function with Parameters</title> </head> <body> <?php function addFunction($num1, $num2) { $sum = $num1 + $num2; echo "Sum of the two numbers is : $sum"; } addFunction(10, 20); ?> </body> </html>

This will display following result:

Sum of the two numbers is : 30

Passing Arguments by Reference:

It is possible to pass arguments to functions by reference. This means that a reference to the variable is manipulated by the function rather than a copy of the variable's value.

Any changes made to an argument in these cases will change the value of the original variable. You can pass an argument by reference by adding an ampersand to the variable name in either the function call or the function definition.

Following example depicts both the cases.

<html> <head> <title>Passing Argument by Reference</title> </head> <body> <?php function addFive($num) { $num += 5; } function addSix(&$num) { $num += 6; } $orignum = 10; addFive( &$orignum ); echo "Original Value is $orignum<br />"; addSix( $orignum ); echo "Original Value is $orignum<br />"; ?> </body> </html>

This will display following result:

Original Value is 15 Original Value is 21

PHP Functions retruning value:

A function can return a value using the return statement in conjunction with a value or object. return stops the execution of the function and sends the value back to the calling code.

You can return more than one value from a function using return array(1,2,3,4).

Following example takes two integer parameters and add them together and then returns their sum to the calling program. Note that return keyword is used to return a value from a function.

<html> <head> <title>Writing PHP Function which returns value</title> </head> <body> <?php function addFunction($num1, $num2) { $sum = $num1 + $num2; return $sum; } $return_value = addFunction(10, 20); echo "Returned value from the function : $return_value ?> </body> </html>

This will display following result:

Returned value from the function : 30

Setting Default Values for Function Parameters:

You can set a parameter to have a default value if the function's caller doesn't pass it.

Following function prints NULL in case use does not pass any value to this function.

<html> <head> <title>Writing PHP Function which returns value</title> </head> <body> <?php function printMe($param = NULL) { print $param; } printMe("This is test"); printMe(); ?> </body> </html>

This will produce following result:

This is test

Dynamic Function Calls:

It is possible to assign function names as strings to variables and then treat these variables exactly as you would the function name itself. Follwoing example depicts this behaviour.

<html> <head> <title>Dynamic Function Calls</title> </head> <body> <?php function sayHello() { echo "Hello<br />"; } $function_holder = "sayHello"; $function_holder(); ?> </body> </html>

This will display following result:

Hello

---

PHP Forms and User Input:

The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.

PHP Form Handling

The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.

Example

The example below contains an HTML form with two input fields and a submit button:

<html> <body> <form action="welcome.php" method="post"> Name: <input type="text" name="fname" /> Age: <input type="text" name="age" /> <input type="submit" /> </form> </body> </html>

When a user fills out the form above and click on the submit button, the form data is sent to a PHP file, called "welcome.php":

"welcome.php" looks like this:

<html> <body> Welcome <?php echo $_POST/GET["fname"]; ?>!<br /> You are <?php echo $_POST/GET["age"]; ?> years old. </body> </html>

Output could be something like this:

Welcome John!

You are 28 years old.

The PHP $_GET and $_POST variables will be explained in the next chapters.

---

Form Validation

User input should be validated on the browser whenever possible (by client scripts). Browser validation is faster and reduces the server load.

You should consider server validation if the user input will be inserted into a database. A good way to validate a form on the server is to post the form to itself, instead of jumping to a different page. The user will then get the error messages on the same page as the form. This makes it easier to discover the error.

---

PHP Files & I/O

Explain following functions related to files:

• Opening a file



• Reading a file



• Writing a file



• Closing a file

Opening and Closing Files

The PHP fopen() function is used to open a file. It requires two arguments stating first the file name and then mode in which to operate.

Files modes can be specified as one of the six options in this table.

Mode	Purpose
r	Opens the file for reading only. Places the file pointer at the beginning of the file.
r+	Opens the file for reading and writing. Places the file pointer at the beginning of the file.
w	Opens the file for writing only. Places the file pointer at the beginning of the file. and truncates the file to zero length. If files does not exist then it attemts to create a file.
w+	Opens the file for reading and writing only. Places the file pointer at the beginning of the file. and truncates the file to zero length. If files does not exist then it attemts to create a file.
a	Opens the file for writing only. Places the file pointer at the end of the file. If files does not exist then it attemts to create a file.
a+	Opens the file for reading and writing only. Places the file pointer at the end of the file. If files does not exist then it attemts to create a file.

If an attempt to open a file fails then fopen returns a value of false otherwise it returns a file pointer which is used for further reading or writing to that file.

After making a changes to the opened file it is important to close it with the fclose() function. The fclose() function requires a file pointer as its argument and then returns true when the closure succeeds or false if it fails.

---

Reading a file

Once a file is opend using fopen() function it can be read with a function called fread(). This function requires two arguments. These must be the file pointer and the length of the file expressed in bytes.

The files's length can be found using the filesize() function which takes the file name as its argument and returns the size of the file expressed in bytes.

So here are the steps required to read a file with PHP.

• Open a file using fopen() function.



• Get the file's length using filesize() function.



• Read the file's content using fread() function.



• Close the file with fclose() function.

The following example assigns the content of a text file to a variable then displays those contents on the web page.

<html> <head> <title>Reading a file using PHP</title> </head> <body> <?php $filename = "/home/user/guest/tmp.txt"; $file = fopen( $filename, "r" ); if( $file == false ) { echo ( "Error in opening file" ); exit(); } $filesize = filesize( $filename ); $filetext = fread( $file, $filesize ); fclose( $file ); echo ( "File size : $filesize bytes" ); echo ( "<pre>$text</pre>" ); ?> </body> </html>

---

Writing a file

A new file can be written or text can be appended to an existing file using the PHP fwrite()function. This function requires two arguments specifying a file pointer and the string of data that is to be written. Optionally a third intger argument can be included to specify the length of the data to write. If the third argument is included, writing would will stop after the specified length has been reached.

The following example creates a new text file then writes a short text heading insite it. After closing this file its existence is confirmed using file_exist() function which takes file name as an argument

<?php $filename = "/home/user/guest/newfile.txt"; $file = fopen( $filename, "w" ); if( $file == false ) { echo ( "Error in opening new file" ); exit(); } fwrite( $file, "This is a simple test\n" ); fclose( $file ); ?> <html> <head> <title>Writing a file using PHP</title> </head> <body> <?php if( file_exist( $filename ) ) { $filesize = filesize( $filename ); $msg = "File created with name $filename "; $msg .= "containing $filesize bytes"; echo ($msg ); } else { echo ("File $filename does not exit" ); } ?> </body> </html>

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Web Technology - Introduction to Web Servers (Jntu-Anantapur)

G.PULLAIAH COLLEGE OF ENGINEERING & TECHNOLOGY KURNOOL.

SUB: WEB TECHNOLOGIES (R09)

UNIT-1

Lecture notes:

Introduction to web servers:

What is web?

A collection of cross-linked “websites” which uses URI.

The consistent use of URIs to represent resources.

HTTP, HTML, and everything built around them(web)

Which provides to invoke the data across universally over the net

What is server?

A server is a computer or device on a network that manages network resources.

Most servers are dedicated. This means that they perform only one task rather than multiple tasks on multiprocessing operating systems, however, a single computer can execute several programs at once

What is web server?

A Web server is a program that generates and transmits responses to client requests for Web resources.

Handling a client request consists of several key steps:

Parsing the request message

Checking that the request is authorized

Associating the URL in the request with a file name

Constructing the response message

Transmitting the response message to the requesting client

The server can generate the response message in a variety of ways:

The server simply retrieves the file associated with the URL and returns the contents to the client.

The server may invoke a script that communicates with other servers or a back-end database to construct the response message.

Web Site versus Web Server?

Web site and Web server are different:

A Web site consists of a collection of Web pages associated with a particular hostname.

A Web server is a program to satisfy client requests for Web resources.

Types Of Web Servers:

1. Apache Web Server

1. IIS Server
2. Xampp Server
3. WAMP Server

Apache Web Server:

Introduction:

Apache Web server is the most commonly used http server today. About 80% of all websites and Intranets use Apache web server to deliver their content to requesting Browsers.

Server side programming languages such as PHP, Perl, Python, Java and many others

The name "Apache" derives from the word "patchy" that the Apache developers used to describe early versions of their software.

The Apache Web server provides a full range of Web server features, including CGI, SSL, and virtual domains. Apache also supports plug-in modules for extensibility. Apache is reliable, free, and relatively easy to configure.

Apache is free software distributed by the Apache Software Foundation. The Apache Software Foundation promotes various free and open source advanced Web technologies.

It can be downloaded and used completely free of cost. The first version of Apache web server, based on the NCSA httpd Web server, was developed in 1995.

Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.

The Internet’s Request / Response Way Of Working

Here’s the Internet’s Request / Response paradigm works.

Whenever a Browser makes an http request such as:http://www.google.com/index.html
the following happens:

http	This is the protocol used for communication between the Browser and the Web server. Since the Browser initiated the communication it has the privilege of setting the communication protocol.
://	This is a separator that separates the protocol from the URL.
www.google.com	This will be translated into a name:value pair i.e. ip:URL by DNS servers. Hence this will translate to an ip74.86.170.172:www.google.com

Download Apache Web Server:

The latest stable build of Apache http server can be downloaded from URLhttp://httpd.apache.org/download.cgi

Downloading the Apache web server

 

Open a browser window and enter http://www.google.com in the address bar and hit GO.

Installing the Apache web server

I recommend to run the Apache HTTP server as a service. This way it is always running and you don't need to start it manually. If you consider manually start and stop because of security issues, then reconsider and use a firewall, preferable one running on an external device like a router.

The next step allows you to select the install type of the Apache web server. The default (Typical program features) is probably right for your situation, so press Next.

Next, you can select the destination folder of the installation. Unless you prefer to use a different folder for some or all of the software you install, I recommend to use the default setting: C:\Program Files\Apache Group\

Finally, after clicking on the Next button you can start the actual installation by pressing the Install button. A few windows pop up and go automatically, and then a Windows Security Alert window appears asking if you want to keep blocking this (Apache HTTP server) program.

 

Windows Security Alert for the Apache HTTP server.

The download process of the Apache Web Server setup file is successfully finished.

Testing the Apache HTTP server installation

In order to test your Apache web server installation, open a browser and enter http://localhost/ into the address bar (unless you used a different value then localhost in the Apache server information step). The Test Page for Apache installation should be displayed into your browser.

Part of the Apache HTTP server test page in Mozilla Firefox

Understanding the Apache server folder structure

The bin folder

The bin folder contains amongst other files the server executable: Apache.exe and a program to control the Apache HTTP server when ran as service: ApacheMonitor.exe. Also contained in this folder are htpasswd.exe and htdigest.exe for making parts of your site(s) restricted.

The cgi-bin folder

The cgi-bin folder has one CGI program written in Perl, printenv.pl, which you can use to test if your Perl installation is working in combination with the Apache HTTP server. If you get a "500 Internal Server Error" when you enter http://localhost/cgi-bin/printenv.pl in the address bar of your browser, you either have Perl not installed, or the configuration of the web server is not right. You might want to check the error.log file in the logs folder in the latter case.

The conf folder

This folder holds the configuration files used by the Apache web server. Of each file used by the server there is a copy which has .default in its name, e.g. httpd.default.conf. The access.conf and srm.conf files are empty (except for comments) by default, and I recommend to not use those files for configuring the server. The httpd.conf file has already been updated by the installation process. I list some of those modified settings below, including a short description and the line number (which might differ with your version).

• Listen 80 - The port the Apache server is using. If you have already a web server running, for example as part of Microsoft Internet Information Services (IIS), you might want to change the number to something different (line 120).
• ServerAdmin admin@localhost - The email address of the server administrator, which is used on, for example, error pages generated by the server (line 198).
• ServerName localhost:80 - The hostname and port the server uses (line 212).

Some of the other settings are omitted since they will be overridden by the name-based virtual hosting set up discussed below.

htdocs

This folder contains the default HTML page you see when you visit http://localhost/ with your web browser. Don't start adding your HTML documents and related files to this folder, but read on.

manual

This folder contains the Apache HTTP server documentation, available as http://localhost/manual/. Note that this folder shows up under the document root thanks to the AliasMatch directive in the httpd.conf server configuration file (line 491).

logs

This folder contains (amongst others) the access.log and error.log files. If anything goes wrong, for example the notorious 500 Internal Server Error, make sure that you check the error.log file. With virtual hosting you can give each site its own log file (discussed below), so be sure to check the right file(s).

Setting up virtual Hosting

To make the configuration of virtual hosts as easy as possible I decided to store the configuration settings into a separate file instead of adding those settings to the Apache server configuration file httpd.conf.

Login to the computer with Administrator rights, and create an empty file named virtual-hosts.conf inside the conf folder of the Apache HTTP server. The default location of this folder after installation is C:\Program Files\Apache Group\Apache2\conf\.

Note: in an earlier version of this article I stored the virtual hosts file inside a folder with limted user rights which implied that this file has the same rights. Since this file is interpreted by the Apache web server this is a security risk if this limited user account is compromised.

Adding the domains to the hosts file

For each website you want to have running locally you have to think up a domain name with great care. I use the same domain name as the real site with lc. added to the front (hence a subdomain) since I am very sure that this subdomain isn't used on the Internet in my case.

Add each domain name to the hosts file used by Windows XP, which is located in the C:\WINDOWS\system32\drivers\etc folder for a default installation. An example configuration might be (comments on top not included for brevity):

127.0.0.1   localhost

127.0.0.1   lc.johnbokma.com    # my personal site

127.0.0.1   lc.castleamber.com  # my company's site

Note that everything after the # character is regarded as a comment. You can use this to add useful comments. The IP address, 127.0.0.1, means "this computer" (localhost). If you want to use the web server in a local network, you have to use an IP address that can be contacted by other computers in the network. Also, you either have to modify all hosts files on each and every computer, or set up a name server.

Including the virtual-hosts.conf file

Add the following line to the end of the httpd.conf file in the C:\Program Files\Apache Group\Apache2\conf folder in order to include the virtual-hosts.conf file and make it part of the configuration of the web server:

Include conf/virtual-hosts.conf

Since the ServerRoot in the default install is set to the folder that contains the conf folder we can use the short relative notation as given above. Note: where filenames are specified, you must use forward slashes instead of backslashes (e.g. conf/virtual-hosts.conf instead of conf\virtual-hosts.conf).

Stopping and starting Apache

After changes have been made to the httpd.conf file and/or the virtual-hosts file, Apache has to be restarted. If you are logged in with Administrator rights the easiest way to do this is by using the Apache monitor which is started when you log in and available via the system tray. Click the right mouse (context menu) button on the red feather icon in the system tray and select the Open Apache Monitor menu entry. You can restart the Apache HTTP server with a single mouse click on the Restart button.

The Apache service monitor.

Note that during installation of the Apache web server a short cut to the Apache service monitor is created in the Startup folder of "All Users" (i.e. C:\Documents and Settings\All Users\Start Menu\Programs\Startup) which is quite useless. Users with limited access rights are not able to control the Apache service but will get the Apache monitor running in their system tray anyway. You might want to move the short cut to the Startup folder of a user with Administrator rights.

Another way to restart Apache is by entering in a command prompt window NET STOP APACHE2 followed by enter, followed by NET START APACHE2 to stop and start the Apache service:

NET STOP APACHE2

The Apache2 service is stopping.

The Apache2 service was stopped successfully.

NET START APACHE2

The Apache2 service is starting.

The Apache2 service was started successfully

Creating virtual hosts on Apache 2.2

This tutorial is intended for use only in a local testing environment on Windows. For a production server, please refer to the official documentation on the Apache site.

ü Apache 2.2 adopts a modular approach to its main configuration file, httpd.conf. Although you can still put everything in the one big file, it's more efficient to use external files, and include only those that you need to implement. Consequently, it's no longer recommended to define virtual hosts at the bottom of httpd.conf. Instead, you include an external file called httpd-vhosts.conf.

ü The other change is that Apache 2.2 imposes stricter permissions than previous series, so you need to add an extra command to the virtual hosts definition to prevent getting the following message when accessing a virtual host:

• Forbidden
  
  
  You don't have permission to access /index.php on this server.

Because of the permissions issue, I recommend creating a top-level folder to hold all virtual hosts in your local development environment. The following instructions assume that all virtual hosts are located in a folder called C:\vhosts.

NOTE: Security restrictions on Windows Vista and Windows 7 prevent you from saving edits to the files referred to in these instructions, even if you are logged in as an administrator. To get around this restriction, open Notepad or your script editor from the Start menu by right-clicking the program name and selecting "Run as Administrator" from the context menu. Then open the relevant files by using File > Open inside the program you have just launched. By default, Notepad shows only files with a .txt file name extension, so you need to select the option to view All Files (*.*) in the Open dialog box. You can then save the files normally after editing them. (If you're using XAMPP, this restriction applies only to steps 2–4.)

1. Create a subfolder inside C:\vhosts for each virtual host that you want to add to your Apache server.

2. Open C:\WINDOWS\system32\drivers\etc\hosts in Notepad or a script editor. Look for the following line at the bottom:

127.0.0.1   localhost

3. On a separate line, enter 127.0.0.1, followed by some space and the name of the virtual host you want to register. For instance, to set up a virtual host called phpdw, enter the following:

127.0.0.1   phpdw

4. Add any further virtual hosts, each one on a separate line and pointing to the same IP address (127.0.0.1). Save the hosts file, and close it.

5. Open C:\Program Files\Apache Software Foundation\Apache2.2\conf\httpd.confin a text editor. If you're using XAMPP, the file is located at C:\xampp\apache\conf\httpd.conf. Scroll down to the Supplemental configuration section at the end, and locate the following section (around line 460):

6. #Virtual hosts

#Include conf/extra/httpd-vhosts.conf

7. Remove the # from the second line so the section now looks like this:

8. #Virtual hosts

Include conf/extra/httpd-vhosts.conf

9. Save httpd.conf and close it.

10. Open C:\Program Files\Apache Software Foundation\Apache2.2\conf\extra\httpd-vhosts.conf in Notepad or a text editor. If you're using XAMPP, the location is C:\xampp\apache\conf\extra\httpd-vhosts.conf. The main section looks like this:

Note: In XAMPP, all lines are commented out. You must remove the hash mark from the beginning of the line that contains the following directive:

NameVirtualHost *.80

11. Position your cursor in the blank space shown on line 15 in the preceding screenshot, and insert the following four lines of code:

12.<Directory C:/vhosts>

13.  Order Deny,Allow

14.  Allow from all

</Directory>

This sets the correct permissions for the folder that contains the sites you want to treat as virtual hosts. If you chose a location other than C:\vhosts as the top-level folder, replace the pathname in the first line. The pathname must use forward slashes in place of the Windows convention of backward slashes. Also surround the pathname in quotes if it contains any spaces.

As long as all your virtual hosts are in subfolders of this top-level folder, this directive sets the correct permissions for all of them. However, if they are in different top-level folders, create a separate <Directory> directive for each one.

15. The code shown on lines 27 through 42 in the preceding screenshot shows examples of how to define virtual hosts (in XAMPP, they're commented out). It shows all the commands that can be used, but only DocumentRoot and ServerName are required.

ü When you enable virtual hosting, Apache disables the main server root, so the first definition needs to reproduce the original server root. You then add each new virtual host within a pair of <VirtualHost> tags, using the location of the site’s web files as the value for DocumentRoot, and the name of the virtual host for ServerName. Again, use forward slashes, and if the path contains any spaces, enclose the whole path in quotes. If your server root is located, like mine, at C:\htdocs, and you are adding phpdw as a virtual host in C:\vhosts, change the code shown on lines 27 through 42 so they look like this (in XAMPP, just add these new directives at the bottom of the file, and set the DocumentRoot for localhost to C:/xampp/htdocs):

<VirtualHost *:80>

  DocumentRoot c:/htdocs

  ServerName localhost

</VirtualHost>

<VirtualHost *:80>

  DocumentRoot c:/vhosts/phpdw

  ServerName phpdw</VirtualHost>

16. Save httpd-vhosts.conf, and restart your computer. All sites in the server root will continue to be accessible through http://localhost/sitename/. Anything in a virtual host will be accessible through a direct address, such as http://phpdw/.

17. If you still have difficulty accessing your virtual hosts, make sure that you have addedindex.php to the DirectoryIndex directive in httpd.conf.

To create a virtual directory on a machine running Apache Web server software:

Note: The Apache Web server uses the term alias instead of virtual directory.

1. Locate the conf/httpd.conf file in the Apache install directory.

2. Add an entry near the end of the file that looks like this. Be careful that it is not in the middle of some other entry:

Alias /site_name "C:\pathname_to_site\your_site_directory"

<Directory "C:\pathname_to_site\your_site_directory">

Options Indexes FollowSymLinks MultiViews ExecCGI

AllowOverride All

Order allow,deny

Allow from all

</Directory>

3. In the entry added in step 2, replace site_name with the alias for your site and replace C:\pathname_to_site\your_site_directory with the actual file path name to your site's root directory. If the server is running on Linux, the format of the path name would be a UNIX path name rather than the Windows-style pathname shown in the example.

4. Restart the Apache server to have the change take effect.

Wamp server:

Setting Up a WAMP Server

ü A WAMP Server is a Windows Machine that has Apache, MySQL, and PHP on it (WAMP – Windows, Apache, MySQL, PHP) To install these before you would have to get the installs and binaries and configure them yourself and set everything up which can be a tedious task as well as very time consuming.

ü Now, thanks to sourceforge, you can get this functionality by simply installing an application. Once you are finished with this tutorial you will be able to follow our web-based tutorials without having a domain name and/or server. Let’s get started. First we need to download our software from wampserver.com.

Once on that site look for the above box to appear and click on Download WAMP Server 2.0

Save the file somewhere that you will be able to get to once it is finished completing. It is approximately 20 Megabytes, so depending on your connection; it may take a few minutes.

You should now see this icon wherever you chose to save the file. Double-click on it to start the installation.

Select to run the file if you are prompted to do so.

You will be prompted to not install this version over WAMP5 1.x. Click yes to continue with the installation.

This first install window simply welcomes you to the installer for this application. Click next to continue.

This window contains the GNU GENERAL PUBLIC LICENSE that will allow you to use this software. Once you review this click the I Accepts radial button and click next to continue.

This box let’s you pick where you would like to install all of the files. You can change this if you like but if you do, bear in mind that you should put it in a folder that does not contain any spaces as some browsers/servers have issues handling spaces in file names. This is also where your web files will be stored under a directory called ‘www’. If you are unsure, leave this default.

This window will allow you to create the desktop icon and the quick launch icon to start the server by the click of a button.

This window just reviews all installation options. Verify the settings are correct and click next to start installing the application.

This is installing the software.

You will get the above prompt to configure FireFox as your default browser for the WAMP Server if you would like, otherwise it will use Internet Explorer.

This window will allow you to configure your server to forward any e-mail that your php creates to a proper server and e-mail account so that they will go to the right person once you are using it. If you don’t know these values or have the ability to use them, just leave them default.

This is the completion window. You have the ability to launch the server automatically after closing this window if you would like. Click Finish to start the application.

Once the server is running, you will see the above icon and the taskbar for the WAMP Server.

INSTALLING, CONFIGURING, AND DEVELOPING WITH XAMPP

About XAMPP and Installation Requirements XAMPP is a small and light Apache distribution containing the most common web development technologies in a single package.

Its contents, small size, and portability make it the ideal tool for students developing and testing applications in PHP and MySQL. XAMPP is available as a free download in two specific packages: full and lite.

While the full package download provides a wide array of development tools, this article will focus on using XAMPP Lite which contains the necessary technologies that meet the Ontario Skills Competition standards. As the name implies, the light version is a small package containing Apache HTTP Server, PHP, MySQL, phpMyAdmin, Openssl, and SQLite. For more details on the packaging and versions

 

Obtaining and Installing XAMPP

As previously mentioned, XAMPP is a free package available for download and use for various web development tasks.

All XAMPP packages and add-ons are distributed through the Apache Friends website at the address: http://www.apachefriends.org/. Once on the website, navigate and find the Windows version of XAMPP Lite and download the self-extracting ZIP archive.

After downloading the archive, run and extract its contents into the root path of a hard disk or USB drive.

For example, the extract path for a local Windows installation would simply be C:\. If extracted properly you will notice a new xampplite directory in the root of your installation disk. In order to test that everything has been installed correctly, first start the Apache HTTP Server by navigating to the xampplite directory and run the apache_start.bat batch file.