Php Basics

PHP BASICSPHP BASICS
Prepared By:Prepared By:
CHIRAG PAHUJACHIRAG PAHUJA
Email Id:Email Id:
chiragpahuja14@hotmchiragpahuja14@hotm
ail.comail.com

What is PHP?
• PHP stands for PHP: Hypertext Preprocessor
• PHP is a server-side scripting language, 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
04/30/13

What is a PHP File?
• PHP files can contain text, HTML tags and scripts
• PHP files are returned to the browser as plain HTML
• PHP files have a file extension of ".php", ".php3", or ".phtml"

Why PHP?
• PHP runs on different platforms (Windows, Linux, Unix, etc.)
• PHP is compatible with almost all servers used today (Apache,
IIS, etc.)
• PHP is FREE to download from the official PHP resource:
www.php.net
• PHP is easy to learn and runs efficiently on the server side

Where to Start?
• To get access to a web server with PHP support, you can:
• Install Apache (or IIS) on your own server, install PHP, and
MySQL
• Or find a web hosting plan with PHP and MySQL support

PHP Syntax
• PHP code is executed on the server, and the plain HTML result
is sent to the browser.

Basic PHP Syntax
• A PHP scripting block always starts with <?php and ends
with ?>.
• A PHP scripting block can be placed anywhere in the
document.
• On servers with shorthand support enabled you can start a
scripting block with <? and end with ?>.

• For maximum compatibility, we recommend that you use the
standard form (<?php) rather than the shorthand form.
<?php
?>
• A PHP file normally contains HTML tags, just like an HTML file,
and some PHP scripting code.

An example of a simple PHP script
<html>
<body>
<?php
echo "Hello World";
?>
</body>
</html>

• There are two basic statements to output text with PHP: echo
and print.
• Note: The file must have a .php extension. If the file has a
.html extension, the PHP code will not be executed.

Comments in PHP
• In PHP, we use // to make a single-line comment or /* and */
to make a large comment block.

PHP Variables
• Variables are used for storing a 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:
$var_name = value;
Example:
<?php
$txt="Hello World!";
$x=16;
?>

PHP is a Loosely Typed Language
• In PHP, a variable does not need to be declared before adding
a value to it.
• In the example above, 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 its value.
• 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.

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)

PHP String Variables
• String variables are used for values that contains characters.
• After we create a string we can manipulate it. A string can be
used directly in a function or it can be stored in a variable.

Example:
<?php
$txt="Hello World";
echo $txt;
?>

The Concatenation Operator
• There is only one string operator in PHP.
• The concatenation operator (.) is used to put two string
values together.
• To concatenate two string variables together, use the
concatenation operator:

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

The strlen() function
• The strlen() function is used to return the length of a string.
Let's find the length of a string:
<?php
echo strlen("Hello world!");
?>

The strpos() function
• The strpos() function is used to search for character within a
string.
• If a match is found, this function will return the position of the
first match. If no match is found, it will return FALSE.

Example:
<?php
echo strpos("Hello world!","world");
?>
Output: 6

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

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

PHP Arrays
• An array stores multiple values in one single variable.
• A variable is a storage area holding a number or text. The
problem is, a variable will hold only one value.
• 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";

PHP Arrays
• 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

Numeric Arrays
• A numeric array stores each array element with a numeric
index.
• There are two methods to create a numeric array.
In the following example the index are automatically assigned
(the index starts at 0):
$cars=array("Saab","Volvo","BMW","Toyota");

In the following example we assign the index manually:
$cars[0]="Saab";
$cars[1]="Volvo";
$cars[2]="BMW";
$cars[3]="Toyota";

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.

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.

PHP Loops
• Often when you write code, you want the same block of code
to run over and over again in a row. Instead of adding several
almost equal lines in a script we can use loops to perform a
task like this.
• In PHP, we have the following looping statements:
• while - loops through a block of code while a specified
condition is true
• do...while - loops through a block of code once, and then
repeats the loop as long as a specified condition is true

Contd…
• 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

The while Loop
• The while loop executes a block of code while a condition is
true.
Syntax
while (condition)
{
code to be executed;
}

Example:
<html>
<body>
<?php
$i=1;
while($i<=5)
{
echo "The number is " . $i . "<br />";
$i++;
}
?> </body> </html>

The do...while Statement
• The do...while statement will always execute the block of
code once, it will then check the condition, and repeat the
loop while the condition is true.
Syntax
do
{
}
while (condition);

Example:
<html>
<body>
<?php
$i=1;
Do
{
$i++;
} while ($i<=5);
?> </body> </html>

The for Loop
• The for loop is used when you know in advance how many
times the script should run.
Syntax
for (init; condition; increment)
{
}

Contd….
Parameters:
• init: Mostly used to set a counter (but can be any code to be
executed once at the beginning of the loop)
• condition: Evaluated for each loop iteration. If it evaluates to
TRUE, the loop continues. If it evaluates to FALSE, the loop
ends.
• increment: Mostly used to increment a counter (but can be
any code to be executed at the end of the loop)

Example:
<html>
<body>
<?php
for ($i=1; $i<=5; $i++)
{
}
?>
</body>
</html>

The foreach Loop
• The foreach loop is used to loop through arrays.
Syntax:
foreach ($array as $value)
{
}
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 Functions
• In PHP, there are more than 700 built-in functions.
A function will be executed by a call to the function
Syntax:
function functionName()
{
}

PHP function guidelines:
• Give the function a name that reflects what the function does
• The function name can start with a letter or underscore (not a
number)

PHP Functions - Adding
parameters
• To add more functionality to a function, we can add
parameters. A parameter is just like a variable
• Parameters are specified after the function name, inside the
parentheses

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.

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

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.
• user will then get the error messages on the same page as the
form. This makes it easier to discover the error.

The $_GET Function
• The built-in $_GET function is used to collect values from a
form sent with method="get".
• Information sent from a form with the GET method is visible
to everyone (it will be displayed in the browser's address bar)
and has limits on the amount of information to send (max.
100 characters).

When to use method="get"?
• When using method="get" in HTML forms, all variable names
and values are displayed in the URL.
Note: This method should not be used when sending
passwords or other sensitive information!
• However, because the variables are displayed in the URL, it is
possible to bookmark the page. This can be useful in some
cases.
• Note: The get method is not suitable for large variable
values; the value cannot exceed 100 characters

The $_POST Function
• The built-in $_POST function is used to collect values from a
form sent with method="post".
• Information sent from a form with the POST method is
invisible to others and has no limits on the amount of
information to send.
• Note: However, there is an 8 Mb max size for the POST
method, by default (can be changed by setting the
post_max_size in the php.ini file).

When to use method="post"?
• Information sent from a form with the POST method is
invisible to others and has no limits on the amount of
information to send.
• However, because the variables are not displayed in the
URL, it is not possible to bookmark the page.

The PHP $_REQUEST Function
• The PHP built-in $_REQUEST function
contains the contents of both $_GET,
$_POST, and $_COOKIE.
• The$_REQUESTfunctioncanbeusedtocollectformdatasentwithboththeGETandPOSTmethods.

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