Php advance

PHP Date() Function
The PHP date() function is used to format a time and/or date.
The PHP Date() Function
The PHP date() function formats a timestamp to a more readable date and time.
A timestamp is a sequence of characters, denoting the date and/or time at which a certain event
occurred.
Syntax
date(format,timestamp)
Parameter Description
format Required. Specifies the format of the timestamp
timestamp Optional. Specifies a timestamp. Default is the current date and
time
PHP Date() - Format the Date
The required format parameter in the date()
function specifies how to format the date/time.
Here are some characters that can be used:
d - Represents the day of the month (01 to
31)
m - Represents a month (01 to 12)
Y - Represents a year (in four digits)
A list of all the characters that can be used in
the format parameter, can be found in our PHP
Date reference.
Other characters, like"/", ".", or "-" can also be
inserted between the letters to add additional
formatting:
<?php
echo date("Y/m/d") . "<br />";
echo date("Y.m.d") . "<br />";
echo date("Y-m-d");
?>
The output of the code above could be something
like this:
2009/05/11
2009.05.11
2009-05-11
PHP Date() - Adding a Timestamp
The optional timestamp parameter in the date()
function specifies a timestamp. If you do not

specify a timestamp, the current date and time
will be used.
The mktime() function returns the Unix
timestamp for a date.
The Unix timestamp contains the number of
seconds between the Unix Epoch (January 1 1970
00:00:00 GMT) and the time specified.
Syntax for mktime()
mktime(hour,minute,second,month,day,year,is_
dst)
To go one day in the future we simply add one to
the day argument of mktime():
<?php
$tomorrow =
mktime(0,0,0,date("m"),date("d")+1,date("Y")
);
echo "Tomorrow is ".date("Y/m/d", $tomorrow);
?>
The output of the code above could be something
like this:
Tomorrow is 2009/05/12
Complete PHP Date Reference
For a complete reference of all date functions, go to
our complete PHP Date Reference.
The reference contains a brief description, and
examples of use, for each function!
PHP Include Files
PHP include and require Statements
In PHP, you can insert the content of one PHP
file into another PHP file before the server
executes it.
The include and require statements are used to
insert useful codes written in other files, in the
flow of execution.
Include and require are identical, except upon
failure:
require will produce a fatal error
(E_COMPILE_ERROR) and stop the script
include will only produce a warning
(E_WARNING) and the script will
continue
So, if you want the execution to go on and show
users the output, even if the include file is
missing, use include. Otherwise, in case of
FrameWork, CMS or a complex PHP application
coding, always use require to include a key file to
the flow of execution. This will help avoid
compromising your application's security and
integrity, just in-case one key file is accidentally
missing.
Including files saves a lot of work. This means
that you can create a standard header, footer, or
menu file for all your web pages. Then, when the
header needs to be updated, you can only update
the header include file.
Syntax
include 'filename';
or

require 'filename';
PHP include and require Statement
Basic Example
Assume that you have a standard header file,
called "header.php". To include the header file in
a page, use include/require:
<html>
<body>
<?php include 'header.php'; ?>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
</body>
</html>
Example 2
Assume we have a standard menu file that
should be used on all pages.
"menu.php":
<a href="/default.php">Home</a>
<a href="/tutorials.php">Tutorials</a>
<a href="/references.php">References</a>
<a href="/examples.php">Examples</a>
<a href="/about.php">About Us</a>
<a href="/contact.php">Contact Us</a>
All pages in the Web site should include this
menu file. Here is how it can be done:
<html>
<body>
<div class="leftmenu">
<?php include 'menu.php'; ?>
</div>
<h1>Welcome to my home page.</h1>
<p>Some text.</p>
</body>
</html>
Example 3
Assume we have an include file with some
variables defined ("vars.php"):
<?php
$color='red';
$car='BMW';
?>
Then the variables can be used in the calling file:
<html>
<body>
<h1>Welcome to my home page.</h1>
<?php include 'vars.php';
echo "I have a $color $car"; // I have a red BMW
?>
</body>
</html>
PHP File Handling
The fopen() function is used to open files in PHP.
Opening a File
The fopen() function is used to open files in PHP.

The first parameter of this function contains the
name of the file to be opened and the second
parameter specifies in which mode the file should
be opened:
<html>
<body>
<?php
$file=fopen("welcome.txt","r");
?>
</body>
</html>
The file may be opened in one of the following modes:
Modes Description
r Read only. Starts at the beginning of the file
r+ Read/Write. Starts at the beginning of the file
w Write only. Opens and clears the contents of file; or creates a new
file if it doesn't exist
w+ Read/Write. Opens and clears the contents of file; or creates a new
file if it doesn't exist
a Append. Opens and writes to the end of the file or creates a new file if
it doesn't exist
a+ Read/Append. Preserves file content by writing to the end of the file
x Write only. Creates a new file. Returns FALSE and an error if file
already exists
x+ Read/Write. Creates a new file. Returns FALSE and an error if file
already exists
Note: If the fopen() function is unable to open the specified file, it returns 0 (false).
Example
The following example generates a message if the
fopen() function is unable to open the specified
file:
<html>
<body>
<?php
$file=fopen("welcome.txt","r") or exit("Unable
to open file!");
?>
</body>
</html>
Closing a File
The fclose() function is used to close an open file:

<?php
$file = fopen("test.txt","r");
//some code to be executed
fclose($file);
?>
Check End-of-file
The feof() function checks if the "end-of-file"
(EOF) has been reached.
The feof() function is useful for looping through
data of unknown length.
Note: You cannot read from files opened in w, a,
and x mode!
if (feof($file)) echo "End of file";
Reading a File Line by Line
The fgets() function is used to read a single line
from a file.
Note: After a call to this function the file pointer
has moved to the next line.
Example
The example below reads a file line by line, until
the end of file is reached:
<?php
$file = fopen("welcome.txt", "r") or exit("Unable
to open file!");
//Output a line of the file until the end is reached
while(!feof($file))
{
echo fgets($file). "<br />";
}
fclose($file);
?>
Reading a File Character by Character
The fgetc() function is used to read a single
character from a file.
Note: After a call to this function the file pointer
moves to the next character.
Example
The example below reads a file character by
character, until the end of file is reached:
<?php
$file=fopen("welcome.txt","r") or exit("Unable
to open file!");
while (!feof($file))
{
echo fgetc($file);
}
fclose($file);
?>
PHP Filesystem Reference
For a full reference of the PHP filesystem
functions, visit our PHP Filesystem Reference.

PHP File Upload
With PHP, it is possible to upload files to the
server.
Create an Upload-File Form
To allow users to upload files from a form can be
very useful.
Look at the following HTML form for uploading
files:
<html>
<body>
<form action="upload_file.php" method="post"
enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file" />
<br />
<input type="submit" name="submit"
value="Submit" />
</form>
</body>
</html>
Notice the following about the HTML form above:
The enctype attribute of the <form> tag
specifies which content-type to use when
submitting the form. "multipart/form-
data" is used when a form requires binary
data, like the contents of a file, to be
uploaded
The type="file" attribute of the <input>
tag specifies that the input should be
processed as a file. For example, when
viewed in a browser, there will be a browse-
button next to the input field
Note: Allowing users to upload files is a big
security risk. Only permit trusted users to perform
file uploads.
Create The Upload Script
The "upload_file.php" file contains the code for
uploading a file:
<?php
if ($_FILES["file"]["error"] > 0)
{
echo "Error: " . $_FILES["file"]["error"] . "<br
/>";
}
else
{
echo "Upload: " . $_FILES["file"]["name"] .
"<br />";
echo "Type: " . $_FILES["file"]["type"] . "<br
/>";
echo "Size: " . ($_FILES["file"]["size"] / 1024)
. " Kb<br />";
echo "Stored in: " .
$_FILES["file"]["tmp_name"];
}
?>
By using the global PHP $_FILES array you can
upload files from a client computer to the remote
server.
The first parameter is the form's input name and
the second index can be either "name", "type",
"size", "tmp_name" or "error". Like this:

$_FILES["file"]["name"] - the name of
the uploaded file
$_FILES["file"]["type"] - the type of the
uploaded file
$_FILES["file"]["size"] - the size in bytes
of the uploaded file
$_FILES["file"]["tmp_name"] - the
name of the temporary copy of the file
stored on the server
$_FILES["file"]["error"] - the error code
resulting from the file upload
This is a very simple way of uploading files. For
security reasons, you should add restrictions on
what the user is allowed to upload.
Restrictions on Upload
In this script we add some restrictions to the file
upload. The user may only upload .gif or .jpeg files
and the file size must be under 20 kb:
<?php
$allowedExts = array("jpg", "jpeg", "gif",
"png");
$extension = end(explode(".",
$_FILES["file"]["name"]));
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] ==
"image/pjpeg"))
&& ($_FILES["file"]["size"] < 20000))
&& in_array($extension, $allowedExts))
{
{
echo "Error: " . $_FILES["file"]["error"] . "<br
/>";
}
else
{
"<br />";
/>";
. " Kb<br />";
echo "Stored in: " .
$_FILES["file"]["tmp_name"];
}
}
else
{
echo "Invalid file";
}
?>
Note: For IE to recognize jpg files the type must be
pjpeg, for FireFox it must be jpeg.
Saving the Uploaded File
The examples above create a temporary copy of the
uploaded files in the PHP temp folder on the
server.
The temporary copied files disappears when the
script ends. To store the uploaded file we need to
copy it to a different location:
<?php
$allowedExts = array("jpg", "jpeg", "gif",
"png");
$extension = end(explode(".",
$_FILES["file"]["name"]));
if ((($_FILES["file"]["type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type"] ==
"image/pjpeg"))

&& ($_FILES["file"]["size"] < 20000))
&& in_array($extension, $allowedExts))
{
{
echo "Return Code: " . $_FILES["file"]["error"]
. "<br />";
}
else
{
"<br />";
/>";
. " Kb<br />";
echo "Temp file: " .
$_FILES["file"]["tmp_name"] . "<br />";
if (file_exists("upload/" .
$_FILES["file"]["name"]))
{
echo $_FILES["file"]["name"] . " already
exists. ";
}
else
{
move_uploaded_file($_FILES["file"]["tmp_n
ame"],
"upload/" . $_FILES["file"]["name"]);
echo "Stored in: " . "upload/" .
$_FILES["file"]["name"];
}
}
}
else
{
echo "Invalid file";
}
?>
The script above checks if the file already exists, if
it does not, it copies the file to the specified folder.
Note: This example saves the file to a new folder
called "upload"
PHP Cookies
A cookie is often used to identify a user.
What is a Cookie?
A cookie is often used to identify a user. A cookie is
a small file that the server embeds on the user's
computer. Each time the same computer requests a
page with a browser, it will send the cookie too.
With PHP, you can both create and retrieve
cookie values.
How to Create a Cookie?
The setcookie() function is used to set a cookie.
Note: The setcookie() function must appear
BEFORE the <html> tag.
Syntax
setcookie(name, value, expire, path, domain);
Example 1
In the example below, we will create a cookie
named "user" and assign the value "Alex Porter"
to it. We also specify that the cookie should expire
after one hour:

<?php
setcookie("user", "Alex Porter", time()+3600);
?>
<html>
.....
Note: The value of the cookie is automatically
URLencoded when sending the cookie, and
automatically decoded when received (to prevent
URLencoding, use setrawcookie() instead).
Example 2
You can also set the expiration time of the cookie
in another way. It may be easier than using
seconds.
<?php
$expire=time()+60*60*24*30;
setcookie("user", "Alex Porter", $expire);
?>
<html>
.....
In the example above the expiration time is set to
a month (60 sec * 60 min * 24 hours * 30 days).
How to Retrieve a Cookie Value?
The PHP $_COOKIE variable is used to retrieve a
cookie value.
In the example below, we retrieve the value of the
cookie named "user" and display it on a page:
<?php
// Print a cookie
echo $_COOKIE["user"];
// A way to view all cookies
print_r($_COOKIE);
?>
In the following example we use the isset()
function to find out if a cookie has been set:
<html>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "Welcome " . $_COOKIE["user"] . "!<br
/>";
else
echo "Welcome guest!<br />";
?>
</body>
</html>
How to Delete a Cookie?
When deleting a cookie you should assure that
the expiration date is in the past.
Delete example:
<?php
// set the expiration date to one hour ago
setcookie("user", "", time()-3600);
?>
What if a Browser Does NOT Support Cookies?
If your application deals with browsers that do
not support cookies, you will have to use other

methods to pass information from one page to
another in your application. One method is to pass
the data through forms (forms and user input are
described earlier in this tutorial).
The form below passes the user input to
"welcome.php" when the user clicks on the
"Submit" button:
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>
Retrieve the values in the "welcome.php" file like
this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br
/>
You are <?php echo $_POST["age"]; ?> years
old.
</body>
</html>
PHP Sessions
A PHP session variable is used to store information
about, or change settings for a user session. Session
variables hold information about one single user,
and are available to all pages in one application.
PHP Session Variables
When you are working with an application, you
open it, do some changes and then you close it. This
is much like a Session. The computer knows who
you are. It knows when you start the application
and when you end. But on the internet there is
one problem: the web server does not know who you
are and what you do because the HTTP address
doesn't maintain state.
A PHP session solves this problem by allowing you
to store user information on the server for later use
(i.e. username, shopping items, etc). However,
session information is temporary and will be
deleted after the user has left the website. If you
need a permanent storage you may want to store
the data in a database.
Sessions work by creating a unique id (UID) for
each visitor and store variables based on this UID.
The UID is either stored in a cookie or is propagated
in the URL.
Starting a PHP Session
Before you can store user information in your
PHP session, you must first start up the session.
Note: The session_start() function must appear
BEFORE the <html> tag:
<?php session_start(); ?>
<html>
<body>

</body>
</html>
The code above will register the user's session with
the server, allow you to start saving user
information, and assign a UID for that user's
session.
Storing a Session Variable
The correct way to store and retrieve session
variables is to use the PHP $_SESSION variable:
<?php
session_start();
// store session data
$_SESSION['views']=1;
?>
<html>
<body>
<?php
//retrieve session data
echo "Pageviews=". $_SESSION['views'];
?>
</body>
</html>
Output:
Pageviews=1
In the example below, we create a simple page-
views counter. The isset() function checks if the
"views" variable has already been set. If "views"
has been set, we can increment our counter. If
"views" doesn't exist, we create a "views"
variable, and set it to 1:
<?php
session_start();
if(isset($_SESSION['views']))
$_SESSION['views']=$_SESSION['views']+1;
else
$_SESSION['views']=1;
echo "Views=". $_SESSION['views'];
?>
Destroying a Session
If you wish to delete some session data, you can use
the unset() or the session_destroy() function.
The unset() function is used to free the specified
session variable:
<?php
session_start();
if(isset($_SESSION['views']))
unset($_SESSION['views]);
?>
You can also completely destroy the session by
calling the session_destroy() function:
<?php
session_destroy();
?>
Note: session_destroy() will reset your session and
you will lose all your stored session data

PHP Sending E-mails
PHP allows you to send e-mails directly from a script.
The PHP mail() Function
The PHP mail() function is used to send emails from inside a script.
Syntax
mail(to,subject,message,headers,parameters)
o Required. Specifies the receiver / receivers of the email
ubject Required. Specifies the subject of the email. Note: This parameter
cannot contain any newline characters
message Required. Defines the message to be sent. Each line should be separated
with a LF (n). Lines should not exceed 70 characters
headers Optional. Specifies additional headers, like From, Cc, and Bcc.
The additional headers should be separated with a CRLF (rn)
parameters Optional. Specifies an additional parameter to the sendmail program
Note: For the mail functions to be available, PHP requires an installed and working email system. The
program to be used is defined by the configuration settings in the php.ini file. Read more in ourPHP Mail
reference.
PHP Simple E-Mail
The simplest way to send an email with PHP is to
send a text email.
In the example below we first declare the
variables ($to, $subject, $message, $from,
$headers), then we use the variables in the
mail() function to send an e-mail:
<?php
$to = "someone@example.com";
$subject = "Test mail";
$message = "Hello! This is a simple email
message.";
$from = "someonelse@example.com";
$headers = "From:" . $from;
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>

PHP Mail Form
With PHP, you can create a feedback-form on
your website. The example below sends a text
message to a specified e-mail address:
<html>
<body>
<?php
if (isset($_REQUEST['email']))
//if "email" is filled out, send email
{
//send email
$email = $_REQUEST['email'] ;
$subject = $_REQUEST['subject'] ;
$message = $_REQUEST['message'] ;
mail("someone@example.com", $subject,
$message, "From:" . $email);
echo "Thank you for using our mail form";
}
else
//if "email" is not filled out, display the form
{
echo "<form method='post'
action='mailform.php'>
Email: <input name='email' type='text'
/><br />
Subject: <input name='subject' type='text'
/><br />
Message:<br />
<textarea name='message' rows='15' cols='40'>
</textarea><br />
<input type='submit' />
</form>";
}
?>
</body>
</html>
This is how the example above works:
First, check if the email input field is
filled out
If it is not set (like when the page is first
visited); output the HTML form
If it is set (after the form is filled out);
send the email from the form
When submit is pressed after the form is
filled out, the page reloads, sees that the
email input is set, and sends the email
Note: This is the simplest way to send e-mail, but
it is not secure. In the next chapter of this tutorial
you can read more about vulnerabilities in e-
mail scripts, and how to validate user input to
make it more secure.
PHP Mail Reference
For more information about the PHP mail()
function, visit our PHP Mail Reference.
PHP Secure E-mails
There is a weakness in the PHP e-mail script in
the previous chapter.
PHP E-mail Injections
First, look at the PHP code from the previous
chapter:

<html>
<body>
<?php
//if "email" is filled out, send email
{
//send email
mail("someone@example.com", "Subject:
$subject",
$message, "From: $email" );
}
else
//if "email" is not filled out, display the form
{
/><br />
/><br />
Message:<br />
</textarea><br />
</form>";
}
?>
</body>
</html>
The problem with the code above is that
unauthorized users can insert data into the mail
headers via the input form.
What happens if the user adds the following text
to the email input field in the form?
someone@example.com%0ACc:person2@example.c
om
%0ABcc:person3@example.com,person3@example.
com,
anotherperson4@example.com,person5@example.
com
%0ABTo:person6@example.com
The mail() function puts the text above into the
mail headers as usual, and now the header has an
extra Cc:, Bcc:, and To: field. When the user clicks
the submit button, the e-mail will be sent to all
of the addresses above!
PHP Stopping E-mail Injections
The best way to stop e-mail injections is to
validate the input.
The code below is the same as in the previous
chapter, but now we have added an input
validator that checks the email field in the form:
<html>
<body>
<?php
function spamcheck($field)
{
//filter_var() sanitizes the e-mail
//address using FILTER_SANITIZE_EMAIL
$field=filter_var($field,
FILTER_SANITIZE_EMAIL);
//filter_var() validates the e-mail
//address using FILTER_VALIDATE_EMAIL
if(filter_var($field,
FILTER_VALIDATE_EMAIL))

{
return TRUE;
}
else
{
return FALSE;
}
}
{//if "email" is filled out, proceed
//check if the email address is invalid
$mailcheck =
spamcheck($_REQUEST['email']);
if ($mailcheck==FALSE)
{
echo "Invalid input";
}
else
{//send email
mail("someone@example.com", "Subject:
$subject",
$message, "From: $email" );
}
}
else
{//if "email" is not filled out, display the form
/><br />
/><br />
Message:<br />
</textarea><br />
</form>";
}
?>
</body>
</html>
In the code above we use PHP filters to validate
input:
The FILTER_SANITIZE_EMAIL filter
removes all illegal e-mail characters from
a string
The FILTER_VALIDATE_EMAIL filter
validates value as an e-mail address
You can read more about filters in our PHP
Filter chapter.
PHP Error Handling
The default error handling in PHP is very simple.
An error message with filename, line number and
a message describing the error is sent to the browser.
PHP Error Handling
When creating scripts and web applications, error
handling is an important part. If your code lacks
error checking code, your program may look very
unprofessional and you may be open to security
risks.
This tutorial contains some of the most common
error checking methods in PHP.
We will show different error handling methods:

Simple "die()" statements
Custom errors and error triggers
Error reporting
Basic Error Handling: Using the die() function
The first example shows a simple script that opens
a text file:
<?php
?>
If the file does not exist you might get an error like
this:
Warning: fopen(welcome.txt) [function.fopen]:
failed to open stream:
No such file or directory
in C:webfoldertest.php on line 2
To avoid that the user gets an error message like
the one above, we test if the file exist before we try
to access it:
<?php
if(!file_exists("welcome.txt"))
{
die("File not found");
}
else
{
}
?>
Now if the file does not exist you get an error like
this:
File not found
The code above is more efficient than the earlier
code, because it uses a simple error handling
mechanism to stop the script after the error.
However, simply stopping the script is not always
the right way to go. Let's take a look at
alternative PHP functions for handling errors
.
Creating a Custom Error Handler
Creating a custom error handler is quite simple. We simply create a special function that can be called
when an error occurs in PHP.
This function must be able to handle a minimum of two parameters (error level and error message) but can
accept up to five parameters (optionally: file, line-number, and the error context):
Syntax
error_function(error_level,error_message,
error_file,error_line,error_context)

error_level Required. Specifies the error report level for the user-defined error. Must be a value numbe
for possible error report levels
error_message Required. Specifies the error message for the user-defined error
error_file Optional. Specifies the filename in which the error occurred
error_line Optional. Specifies the line number in which the error occurred
error_context Optional. Specifies an array containing every variable, and their values, in use when t
Error Report levels
These error report levels are the different types of error the user-defined error handler can be used for:
Value Constant Description
2 E_WARNING Non-fatal run-time errors. Execution of the script is not halted
8 E_NOTICE Run-time notices. The script found something that might be an error
happen when running a script normally
256 E_USER_ERROR Fatal user-generated error. This is like an E_ERROR set by the progra
PHP function trigger_error()
512 E_USER_WARNING Non-fatal user-generated warning. This is like an E_WARNING se
programmer using the PHP function trigger_error()
1024 E_USER_NOTICE User-generated notice. This is like an E_NOTICE set by the programm
function trigger_error()
4096 E_RECOVERABLE_ERROR Catchable fatal error. This is like an E_ERROR but can be caught b
handle (see also set_error_handler())
8191 E_ALL All errors and warnings (E_STRICT became a part of E_ALL in PH
Now lets create a function to handle errors:
function customError($errno, $errstr)
{
echo "<b>Error:</b> [$errno] $errstr<br />";
echo "Ending Script";
die();
}
The code above is a simple error handling function.
When it is triggered, it gets the error level and an
error message. It then outputs the error level and
message and terminates the script.

Now that we have created an error handling
function we need to decide when it should be
triggered.
Set Error Handler
The default error handler for PHP is the built in
error handler. We are going to make the function
above the default error handler for the duration of
the script.
It is possible to change the error handler to apply
for only some errors, that way the script can
handle different errors in different ways.
However, in this example we are going to use our
custom error handler for all errors:
set_error_handler("customError");
Since we want our custom function to handle all
errors, the set_error_handler() only needed one
parameter, a second parameter could be added to
specify an error level.
Example
Testing the error handler by trying to output
variable that does not exist:
<?php
//error handler function
{
echo "<b>Error:</b> [$errno] $errstr";
}
//set error handler
set_error_handler("customError");
//trigger error
echo($test);
?>
The output of the code above should be something
like this:
Error: [8] Undefined variable: test
Trigger an Error
In a script where users can input data it is useful
to trigger errors when an illegal input occurs. In
PHP, this is done by the trigger_error() function.
Example
In this example an error occurs if the "test"
variable is bigger than "1":
<?php
$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or below");
}
?>
like this:
Notice: Value must be 1 or below
An error can be triggered anywhere you wish in a
script, and by adding a second parameter, you can
specify what error level is triggered.
Possible error types:
E_USER_ERROR - Fatal user-generated
run-time error. Errors that can not be
recovered from. Execution of the script is
halted

E_USER_WARNING - Non-fatal user-
generated run-time warning. Execution of
the script is not halted
E_USER_NOTICE - Default. User-
generated run-time notice. The script
found something that might be an error,
but could also happen when running a
script normally
Example
In this example an E_USER_WARNING occurs if
the "test" variable is bigger than "1". If an
E_USER_WARNING occurs we will use our
custom error handler and end the script:
<?php
{
echo "Ending Script";
die();
}
//set error handler
set_error_handler("customError",E_USER_WAR
NING);
//trigger error
$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or
below",E_USER_WARNING);
}
?>
like this:
Error: [512] Value must be 1 or below
Ending Script
Now that we have learned to create our own errors
and how to trigger them, lets take a look at error
logging.
Error Logging
By default, PHP sends an error log to the server's
logging system or a file, depending on how the
error_log configuration is set in the php.ini file.
By using the error_log() function you can send
error logs to a specified file or a remote destination.
Sending error messages to yourself by e-mail can
be a good way of getting notified of specific errors.
Send an Error Message by E-Mail
In the example below we will send an e-mail with
an error message and end the script, if a specific
error occurs:
<?php
{
echo "Webmaster has been notified";
error_log("Error: [$errno] $errstr",1,
"someone@example.com","From:
webmaster@example.com");
}
//set error handler
set_error_handler("customError",E_USER_WAR
NING);
//trigger error

$test=2;
if ($test>1)
{
trigger_error("Value must be 1 or
below",E_USER_WARNING);
}
?>
like this:
Webmaster has been notified
And the mail received from the code above looks
like this:
This should not be used with all errors. Regular
errors should be logged on the server using the
default PHP logging system.
PHP Exception Handling
Exceptions are used to change the normal flow of a
script if a specified error occurs.
What is an Exception
With PHP 5 came a new object oriented way of
dealing with errors.
Exception handling is used to change the normal
flow of the code execution if a specified error
(exceptional) condition occurs. This condition is
called an exception.
This is what normally happens when an
exception is triggered:
The current code state is saved
The code execution will switch to a
predefined (custom) exception handler
function
Depending on the situation, the handler
may then resume the execution from the
saved code state, terminate the script
execution or continue the script from a
different location in the code
We will show different error handling methods:
Basic use of Exceptions
Creating a custom exception handler
Multiple exceptions
Re-throwing an exception
Setting a top level exception handler
Note: Exceptions should only be used with error
conditions, and should not be used to jump to
another place in the code at a specified point.
Basic Use of Exceptions
When an exception is thrown, the code following
it will not be executed, and PHP will try to find
the matching "catch" block.
If an exception is not caught, a fatal error will be
issued with an "Uncaught Exception" message.
Lets try to throw an exception without catching
it:
<?php
//create function with an exception
function checkNum($number)

{
if($number>1)
{
throw new Exception("Value must be 1 or
below");
}
return true;
}
//trigger exception
checkNum(2);
?>
The code above will get an error like this:
Fatal error: Uncaught exception 'Exception'
with message 'Value must be 1 or below' in
C:webfoldertest.php:6
Stack trace: #0 C:webfoldertest.php(12):
checkNum(28) #1 {main} thrown
Try, throw and catch
To avoid the error from the example above, we need
to create the proper code to handle an exception.
Proper exception code should include:
1. Try - A function using an exception should
be in a "try" block. If the exception does not
trigger, the code will continue as normal.
However if the exception triggers, an
exception is "thrown"
2. Throw - This is how you trigger an
exception. Each "throw" must have at
least one "catch"
3. Catch - A "catch" block retrieves an
exception and creates an object containing
the exception information
Lets try to trigger an exception with valid code:
<?php
//create function with an exception
function checkNum($number)
{
if($number>1)
{
throw new Exception("Value must be 1 or
below");
}
return true;
}
//trigger exception in a "try" block
try
{
checkNum(2);
//If the exception is thrown, this text will not be
shown
echo 'If you see this, the number is 1 or below';
}
//catch exception
catch(Exception $e)
{
echo 'Message: ' .$e->getMessage();
}
?>
The code above will get an error like this:
Message: Value must be 1 or below
Example explained:
The code above throws an exception and catches it:
1. The checkNum() function is created. It
checks if a number is greater than 1. If it
is, an exception is thrown
2. The checkNum() function is called in a
"try" block

3. The exception within the checkNum()
function is thrown
4. The "catch" block retrives the exception
and creates an object ($e) containing the
exception information
5. The error message from the exception is
echoed by calling $e->getMessage() from
the exception object
However, one way to get around the "every throw
must have a catch" rule is to set a top level
exception handler to handle errors that slip
through.
Creating a Custom Exception Class
Creating a custom exception handler is quite
simple. We simply create a special class with
functions that can be called when an exception
occurs in PHP. The class must be an extension of
the exception class.
The custom exception class inherits the properties
from PHP's exception class and you can add
custom functions to it.
Lets create an exception class:
<?php
class customException extends Exception
{
public function errorMessage()
{
//error message
$errorMsg = 'Error on line '.$this->getLine().'
in '.$this->getFile()
.': <b>'.$this->getMessage().'</b> is not a
valid E-Mail address';
return $errorMsg;
}
}
$email = "someone@example...com";
try
{
//check if
if(filter_var($email,
FILTER_VALIDATE_EMAIL) === FALSE)
{
//throw exception if email is not valid
throw new customException($email);
}
}
catch (customException $e)
{
//display custom message
echo $e->errorMessage();
}
?>
The new class is a copy of the old exception class
with an addition of the errorMessage() function.
Since it is a copy of the old class, and it inherits
the properties and methods from the old class, we
can use the exception class methods like getLine()
and getFile() and getMessage().
Example explained:
The code above throws an exception and catches it
with a custom exception class:
1. The customException() class is created as
an extension of the old exception class. This
way it inherits all methods and properties
from the old exception class
2. The errorMessage() function is created.
This function returns an error message if
an e-mail address is invalid

3. The $email variable is set to a string that
is not a valid e-mail address
4. The "try" block is executed and an
exception is thrown since the e-mail address
is invalid
5. The "catch" block catches the exception
and displays the error message
Multiple Exceptions
It is possible for a script to use multiple exceptions
to check for multiple conditions.
It is possible to use several if..else blocks, a switch,
or nest multiple exceptions. These exceptions can
use different exception classes and return different
error messages:
<?php
{
{
//error message
$errorMsg = 'Error on line '.$this->getLine().' in
'.$this->getFile()
.': <b>'.$this->getMessage().'</b> is not a
valid E-Mail address';
return $errorMsg;
}
}
$email = "someone@example.com";
try
{
//check if
if(filter_var($email,
FILTER_VALIDATE_EMAIL) === FALSE)
{
}
//check for "example" in mail address
if(strpos($email, "example") !== FALSE)
{
throw new Exception("$email is an example e-
mail");
}
}
{
}
catch(Exception $e)
{
echo $e->getMessage();
}
?>
Example explained:
The code above tests two conditions and throws an
exception if any of the conditions are not met:
is a valid e-mail address, but contains the
string "example"
4. The "try" block is executed and an
exception is not thrown on the first
condition

5. The second condition triggers an exception
since the e-mail contains the string
"example"
and displays the correct error message
If the exception thrown were of the class
customException and there were no
customException catch, only the base exception
catch, the exception would be handled there.
Re-throwing Exceptions
Sometimes, when an exception is thrown, you
may wish to handle it differently than the
standard way. It is possible to throw an exception
a second time within a "catch" block.
A script should hide system errors from users.
System errors may be important for the coder, but
is of no interest to the user. To make things easier
for the user you can re-throw the exception with a
user friendly message:
<?php
{
{
//error message
$errorMsg = $this->getMessage().' is not a
valid E-Mail address.';
return $errorMsg;
}
}
$email = "someone@example.com";
try
{
try
{
//check for "example" in mail address
if(strpos($email, "example") !== FALSE)
{
throw new Exception($email);
}
}
catch(Exception $e)
{
//re-throw exception
}
}
{
//display custom message
}
?>
Example explained:
The code above tests if the email-address contains
the string "example" in it, if it does, the exception
is re-thrown:
is a valid e-mail address, but contains the
string "example"

4. The "try" block contains another "try"
block to make it possible to re-throw the
exception
5. The exception is triggered since the e-mail
contains the string "example"
and re-throws a "customException"
7. The "customException" is caught and
displays an error message
If the exception is not caught in its current "try"
block, it will search for a catch block on "higher
levels".
Set a Top Level Exception Handler
The set_exception_handler() function sets a user-
defined function to handle all uncaught
exceptions.
<?php
function myException($exception)
{
echo "<b>Exception:</b> " , $exception-
>getMessage();
}
set_exception_handler('myException');
throw new Exception('Uncaught Exception
occurred');
?>
like this:
Exception: Uncaught Exception occurred
In the code above there was no "catch" block.
Instead, the top level exception handler triggered.
This function should be used to catch uncaught
exceptions.
Rules for exceptions
Code may be surrounded in a try block, to
help catch potential exceptions
Each try block or "throw" must have at
least one corresponding catch block
Multiple catch blocks can be used to catch
different classes of exceptions
Exceptions can be thrown (or re-thrown)
in a catch block within a try block
A simple rule: If you throw something, you have
to catch it.
PHP Filter
PHP filters are used to validate and filter data
coming from insecure sources, like user input.
What is a PHP Filter?
A PHP filter is used to validate and filter data
coming from insecure sources.
To test, validate and filter user input or custom
data is an important part of any web
application.
The PHP filter extension is designed to make data
filtering easier and quicker.
Why use a Filter?

Almost all web applications depend on external
input. Usually this comes from a user or another
application (like a web service). By using filters
you can be sure your application gets the correct
input type.
You should always filter all external data!
Input filtering is one of the most important
application security issues.
What is external data?
Input data from a form
Cookies
Web services data
Server variables
Database query results
Functions and Filters
To filter a variable, use one of the following filter
functions:
filter_var() - Filters a single variable
with a specified filter
filter_var_array() - Filter several
variables with the same or different filters
filter_input - Get one input variable and
filter it
filter_input_array - Get several input
variables and filter them with the same or
different filters
In the example below, we validate an integer
using the filter_var() function:
<?php
$int = 123;
if(!filter_var($int, FILTER_VALIDATE_INT))
{
echo("Integer is not valid");
}
else
{
echo("Integer is valid");
}
?>
The code above uses the
"FILTER_VALIDATE_INT" filter to filter the
variable. Since the integer is valid, the output of
the code above will be: "Integer is valid".
If we try with a variable that is not an integer
(like "123abc"), the output will be: "Integer is
not valid".
For a complete list of functions and filters, visit
our PHP Filter Reference.
Validating and Sanitizing
There are two kinds of filters:
Validating filters:
Are used to validate user input
Strict format rules (like URL or E-Mail
validating)
Returns the expected type on success or
FALSE on failure
Sanitizing filters:
Are used to allow or disallow specified
characters in a string
No data format rules
Always return the string

Options and Flags
Options and flags are used to add additional
filtering options to the specified filters.
Different filters have different options and flags.
In the example below, we validate an integer
using the filter_var() and the "min_range" and
"max_range" options:
<?php
$var=300;
$int_options = array(
"options"=>array
(
"min_range"=>0,
"max_range"=>256
)
);
if(!filter_var($var, FILTER_VALIDATE_INT,
$int_options))
{
echo("Integer is not valid");
}
else
{
echo("Integer is valid");
}
?>
Like the code above, options must be put in an
associative array with the name "options". If a
flag is used it does not need to be in an array.
Since the integer is "300" it is not in the specified
range, and the output of the code above will be:
"Integer is not valid".
For a complete list of functions and filters, visit
our PHP Filter Reference. Check each filter to see
what options and flags are available.
Validate Input
Let's try validating input from a form.
The first thing we need to do is to confirm that the
input data we are looking for exists.
Then we filter the input data using the
filter_input() function.
In the example below, the input variable "email"
is sent to the PHP page:
<?php
if(!filter_has_var(INPUT_GET, "email"))
{
echo("Input type does not exist");
}
else
{
if (!filter_input(INPUT_GET, "email",
FILTER_VALIDATE_EMAIL))
{
echo "E-Mail is not valid";
}
else
{
echo "E-Mail is valid";
}
}
?>
Example Explained
The example above has an input (email) sent to
it using the "GET" method:

1. Check if an "email" input variable of the
"GET" type exist
2. If the input variable exists, check if it is a
valid e-mail address
Sanitize Input
Let's try cleaning up an URL sent from a form.
First we confirm that the input data we are
looking for exists.
Then we sanitize the input data using the
filter_input() function.
In the example below, the input variable "url" is
sent to the PHP page:
<?php
if(!filter_has_var(INPUT_POST, "url"))
{
echo("Input type does not exist");
}
else
{
$url = filter_input(INPUT_POST,
"url", FILTER_SANITIZE_URL);
}
?>
Example Explained
The example above has an input (url) sent to it
using the "POST" method:
1. Check if the "url" input of the "POST"
type exists
2. If the input variable exists, sanitize (take
away invalid characters) and store it in
the $url variable
If the input variable is a string like this
"http://www.W3ååSchøøools.com/", the $url
variable after the sanitizing will look like this:
http://www.W3Schools.com/
Filter Multiple Inputs
A form almost always consist of more than one
input field. To avoid calling the filter_var or
filter_input functions over and over, we can use
the filter_var_array or the filter_input_array
functions.
In this example we use the filter_input_array()
function to filter three GET variables. The
received GET variables is a name, an age and an
e-mail address:
<?php
$filters = array
(
"name" => array
(
"filter"=>FILTER_SANITIZE_STRING
),
"age" => array
(
"filter"=>FILTER_VALIDATE_INT,
"options"=>array
(
"min_range"=>1,
"max_range"=>120
)
),
"email"=> FILTER_VALIDATE_EMAIL
);
$result = filter_input_array(INPUT_GET,

$filters);
if (!$result["age"])
{
echo("Age must be a number between 1 and
120.<br />");
}
elseif(!$result["email"])
{
echo("E-Mail is not valid.<br />");
}
else
{
echo("User input is valid");
}
?>
Example Explained
The example above has three inputs (name, age
and email) sent to it using the "GET" method:
1. Set an array containing the name of
input variables and the filters used on the
specified input variables
2. Call the filter_input_array() function
with the GET input variables and the
array we just set
3. Check the "age" and "email" variables in
the $result variable for invalid inputs. (If
any of the input variables are invalid,
that input variable will be FALSE after
the filter_input_array() function)
The second parameter of the filter_input_array()
function can be an array or a single filter ID.
If the parameter is a single filter ID all values in
the input array are filtered by the specified filter.
If the parameter is an array it must follow these
rules:
Must be an associative array containing
an input variable as an array key (like
the "age" input variable)
The array value must be a filter ID or an
array specifying the filter, flags and
options
Using Filter Callback
It is possible to call a user defined function and use
it as a filter using the FILTER_CALLBACK
filter. This way, we have full control of the data
filtering.
You can create your own user defined function or
use an existing PHP function
The function you wish to use to filter is specified
the same way as an option is specified. In an
associative array with the name "options"
In the example below, we use a user created
function to convert all "_" to whitespaces:
<?php
function convertSpace($string)
{
return str_replace("_", " ", $string);
}
$string = "Peter_is_a_great_guy!";
echo filter_var($string, FILTER_CALLBACK,
array("options"=>"convertSpace"));
?>
The result from the code above should look like
this:
Peter is a great guy!

Example Explained
The example above converts all "_" to whitespaces:
1. Create a function to replace "_" to
whitespaces
2. Call the filter_var() function with the
FILTER_CALLBACK filter and an array
containing our function

Php advance

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