PHP Syntax

You cannot view the PHP source code by selecting "View source" in the browser - you will only see the output from the PHP file, which is plain HTML. This is because the scripts are executed on the server before the result is sent back to the browser.

Basic PHP Syntax

A PHP scripting block always starts with 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 .

However, for maximum compatibility, we recommend that you use the standard form (

?>

A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.

Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:

echo "Hello World";

?>

Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.

There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".

Comments in PHP

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

//This is a comment

/*

This is

a comment

block

*/

?>

Chapter 4

PHP Variables

Variables are used for storing values, such as numbers, strings or function results, so that they can be used many times in a script.

Variables in PHP

All variables in PHP start with a $ sign symbol. Variables may contain strings, numbers, or arrays.

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

$txt="Hello World";

echo $txt;

?>

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

$txt1="Hello World";

$txt2="1234";

echo $txt1 . " " . $txt2 ;

?>

The output of the script above will be: "Hello World 1234".

Variable Naming Rules

• A variable name must start with a letter or an underscore "_"
• A variable name can only contain alpha-numeric characters and underscores (a-Z, 0-9, and _ )
• A variable name should not contain spaces. If a variable name should be more than one word, it should be separated with underscore ($my_string), or with capitalization ($myString)

Chapter 5

PHP Operators

Operators are used to operate on values.

PHP Operators

This section lists the different operators used in PHP.

Arithmetic Operators

Assignment Operators

Comparison Operators

Logical Operators

Chapter 6

PHP If...Else Statements

The if, elseif and else statements in PHP are used to perform different actions based on different conditions.

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.

You can use conditional statements in your code to do this.

• if...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

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!":

$d=date("D");

if ($d=="Fri")

  echo "Have a nice weekend!"; 

else

  echo "Have a nice day!"; 

?>

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

$d=date("D");

if ($d=="Fri")

  {

  echo "Hello!

"; 

  echo "Have a nice weekend!";

  echo "See you on Monday!";

  }

?>

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!":

$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!"; 

?>

Chapter 7

PHP Switch Statement

The Switch statement in PHP is used to perform one of several different actions based on one of several different conditions.

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

This is how it works:

• A single expression (most often a variable) is evaluated once
• The value of the expression is compared with the values for each case in the structure
• If there is a match, the code associated with that case is executed
• After a code is executed, break is used to stop the code from running into the next case
• The default statement is used if none of the cases are true

switch ($x)

{

case 1:

  echo "Number 1";

  break;

case 2:

  echo "Number 2";

  break;

case 3:

  echo "Number 3";

  break;

default:

  echo "No number between 1 and 3";

}

?>

Chapter 8

PHP Arrays

An array can store one or more values in a single variable name.

What is an array?

When working with PHP, sooner or later, you might want to create many similar variables.

Instead of having many similar variables, you can store the data as elements in an array.

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

There are three different kind of arrays:

• Numeric array - An array with a numeric ID key
• 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 element with a numeric ID key.

There are different ways to create a numeric array.

Example 1

In this example the ID key is automatically assigned:

$names = array("Peter","Quagmire","Joe");

Example 2

In this example we assign the ID key manually:

$names[0] = "Peter";

$names[1] = "Quagmire";

$names[2] = "Joe";

The ID keys can be used in a script:

$names[0] = "Peter";

$names[1] = "Quagmire";

$names[2] = "Joe";

echo $names[1] . " and " . $names[2] . 

" are ". $names[0] . "'s neighbors";

?>

The code above will output:

Quagmire and Joe are Peter's neighbors

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:

$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

  )

) 

Chapter 9

PHP Looping

Looping statements in PHP are used to execute the same block of code a specified number of times.

Looping

Very often when you write code, you want the same block of code to run a number of times. You can use looping statements in your code to perform this.

In PHP we have the following looping statements:

• 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 true
• for - loops through a block of code a specified number of times
• foreach - loops through a block of code for each element in an array

The while Statement

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

Syntax

while (condition)

code to be executed;

Example

The following example demonstrates a loop that will continue to run as long as the variable i is less than, or equal to 5. i will increase by 1 each time the loop runs:

$i=1;

while($i<=5)

  {

  echo "The number is " . $i . "

";

  $i++;

  }

?>

The do...while 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.

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 5:

$i=0;

do

  {

  $i++;

  echo "The number is " . $i . "

";

  }

while ($i<5);

?>

The for Statement

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

Syntax

for (initialization; condition; increment)

{

  code to be executed;

}

Note: The for statement has three parameters. The first parameter initializes variables, the second parameter holds the condition, and the third parameter contains the increments required to implement the loop. If more than one variable is included in the initialization or the increment parameter, they should be separated by commas. The condition must evaluate to true or false.

Example

The following example prints the text "Hello World!" five times:

for ($i=1; $i<=5; $i++)

{

  echo "Hello World!

";

}

?>

The foreach Statement

The foreach statement is used to loop through arrays.

For every loop, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop, you'll be looking at the next element.

Syntax

foreach (array as value)

{

    code to be executed;

}

Example

The following example demonstrates a loop that will print the values of the given array:

$arr=array("one", "two", "three");

foreach ($arr as $value)

{

  echo "Value: " . $value . "

";

}

?>

Chapter 10

PHP Functions

The real power of PHP comes from its functions.

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

PHP Functions

In this tutorial we will show you how to create your own functions.

For a reference and examples of the built-in functions, please visit our PHP Reference.

Create a PHP Function

A function is a block of code that can be executed whenever we need it.

Creating PHP functions:

• All functions start with the word "function()"
• Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
• Add a "{" - The function code starts after the opening curly brace
• Insert the function code
• Add a "}" - The function is finished by a closing curly brace

Example

A simple function that writes my name when it is called:

function writeMyName()

  {

  echo "Kai Jim Refsnes";

  }

writeMyName();

?>

ml>

Use a PHP Function

Now we will use the function in a PHP script:

function writeMyName()

  {

  echo "Kai Jim Refsnes";

  }

echo "Hello world!

";

echo "My name is ";

writeMyName();

echo ".

That's right, ";

writeMyName();

echo " is my name.";

?>

The output of the code above will be:

Hello world!

My name is Kai Jim Refsnes.

That's right, Kai Jim Refsnes is my name.

PHP Functions - Adding parameters

Our first function (writeMyName()) is a very simple function. It only writes a static string.

To add more functionality to a function, we can add parameters. A parameter is just like a variable.

You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.

Example 1

The following example will write different first names, but the same last name:

function writeMyName($fname)

  {

  echo $fname . " Refsnes.

";

  }

echo "My name is ";

writeMyName("Kai Jim");

echo "My name is ";

writeMyName("Hege");

echo "My name is ";

writeMyName("Stale");

?>

The output of the code above will be:

My name is Kai Jim Refsnes.

My name is Hege Refsnes.

My name is Stale Refsnes.

Example 2

The following function has two parameters:

function writeMyName($fname,$punctuation)

  {

  echo $fname . " Refsnes" . $punctuation . "

";

  }

echo "My name is ";

writeMyName("Kai Jim",".");

echo "My name is ";

writeMyName("Hege","!");

echo "My name is ";

writeMyName("Ståle","...");

?>

The output of the code above will be:

My name is Kai Jim Refsnes.

My name is Hege Refsnes!

My name is Ståle Refsnes...

PHP Functions - Return values

Functions can also be used to return values.

Example

function add($x,$y)

  {

  $total = $x + $y;

  return $total;

  }

echo "1 + 16 = " . add(1,16)

?>

The output of the code above will be:

1 + 16 = 17

Chapter 11

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.

Form example:

Name: 
Age: 

The example HTML page above contains two input fields and a submit button. When the user fills in this form and click on the submit button, the form data is sent to the "welcome.php" file.

The "welcome.php" file looks like this:

Welcome .

You are  years old.

A sample output of the above script may be:

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 (JavaScript)). Browser validation is faster and you reduce the server load.

You should consider using 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.

Chapter 12

PHP $_GET

The $_GET variable is used to collect values from a form with method="get".

The $_GET Variable

The $_GET variable is an array of variable names and values sent by the HTTP GET method.

The $_GET variable is used to collect values from a form 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 it has limits on the amount of information to send (max. 100 characters).

Example

Name: 
Age: 

When the user clicks the "Submit" button, the URL sent could look something like this:

http://www.w3schools.com/welcome.php?name=Peter&age=37

The "welcome.php" file can now use the $_GET variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_GET array):

Welcome .

You are  years old!

Why use $_GET?

Note: When using the $_GET variable all variable names and values are displayed in the URL. So 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 HTTP GET method is not suitable on large variable values; the value cannot exceed 100 characters.

The $_REQUEST Variable

The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.

The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.

Example

Welcome .

You are  years old!

Chapter 13

PHP $_POST

The $_POST variable is used to collect values from a form with method="post".

The $_POST Variable

The $_POST variable is an array of variable names and values sent by the HTTP POST method.

The $_POST variable is used to collect values from a form 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.

Example

Enter your name: 
Enter your age: 

When the user clicks the "Submit" button, the URL will not contain any form data, and will look something like this:

http://www.w3schools.com/welcome.php

The "welcome.php" file can now use the $_POST variable to catch the form data (notice that the names of the form fields will automatically be the ID keys in the $_POST array):

Welcome .

You are  years old!

Why use $_POST?

• Variables sent with HTTP POST are not shown in the URL
• Variables have no length limit

However, because the variables are not displayed in the URL, it is not possible to bookmark the page.

The $_REQUEST Variable

The PHP $_REQUEST variable contains the contents of both $_GET, $_POST, and $_COOKIE.

The PHP $_REQUEST variable can be used to get the result from form data sent with both the GET and POST methods.

Example

Welcome .

You are  years old!

Chapter 14

PHP Date()

The PHP date() function is used to format a time or a date.

The PHP Date() Function

The PHP date() function formats a timestamp to a more readable date and time.

Syntax

date(format,timestamp)

PHP Date - What is a Timestamp?

A timestamp is the number of seconds since January 1, 1970 at 00:00:00 GMT. This is also known as the Unix Timestamp.

PHP Date - Format the Date

The first parameter in the date() function specifies how to format the date/time. It uses letters to represent date and time formats. Here are some of the letters that can be used:

• d - The day of the month (01-31)
• m - The current month, as a number (01-12)
• Y - The current year in four digits

An overview of all the letters 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:

echo date("Y/m/d");

echo "

";

echo date("Y.m.d");

echo "

";

echo date("Y-m-d");

?>

The output of the code above could be something like this:

2006/07/11

2006.07.11

2006-07-11

PHP Date - Adding a Timestamp

The second parameter in the date() function specifies a timestamp. This parameter is optional. If you do not supply a timestamp, the current time will be used.

In our next next example we will use the mktime() function to create a timestamp for tomorrow.

The mktime() function returns the Unix timestamp for a specified date.

Syntax

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():

$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 2006/07/12

PHP Date - Reference

For more information about all the PHP date functions, please visit our PHP Date Reference.

Chapter 15

PHP Include File

Server Side Includes (SSI) are used to create functions, headers, footers, or elements that will be reused on multiple pages.

Server Side Includes

You can insert the content of a file into a PHP file before the server executes it, with the include() or require() function. The two functions are identical in every way, except how they handle errors. The include() function generates a warning (but the script will continue execution) while the require() function generates a fatal error (and the script execution will stop after the error).

These two functions are used to create functions, headers, footers, or elements that can be reused on multiple pages.

This can save the developer a considerable amount of time. This means that you can create a standard header or menu file that you want all your web pages to include. When the header needs to be updated, you can only update this one include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all web pages).

The include() Function

The include() function takes all the text in a specified file and copies it into the file that uses the include function.

Example 1

Assume that you have a standard header file, called "header.php". To include the header file in a page, use the include() function, like this:

<>Welcome to my home page

Some text

<>

Example 2

Now, let's assume we have a standard menu file that should be used on all pages (include files usually have a ".php" extension). Look at the "menu.php" file below:

Home |

About Us | 

Contact Us

The three files, "default.php", "about.php", and "contact.php" should all include the "menu.php" file. Here is the code in "default.php":

Welcome to my home page

Some text

If you look at the source code of the "default.php" in a browser, it will look something like this:

Home |

About Us | 

Contact Us

Welcome to my home page

Some text

And, of course, we would have to do the same thing for "about.php" and "contact.php". By using include files, you simply have to update the text in the "menu.php" file if you decide to rename or change the order of the links or add another web page to the site.

The require() Function

The require() function is identical to include(), they only handle errors differently.

The include() function generates a warning (but the script will continue execution) while the require() function generates a fatal error (and the script execution will stop after the error).

If you include a file with the include() function and an error occurs, you might get an error message like the one below.

PHP code:

include("wrongFile.php");

echo "Hello World!";

?>

Error message:

Warning: include(wrongFile.php) [function.include]:

failed to open stream:

No such file or directory in C:\home\website\test.php on line 5

Warning: include() [function.include]:

Failed opening 'wrongFile.php' for inclusion

(include_path='.;C:\php5\pear')

in C:\home\website\test.php on line 5

Hello World!

Notice that the echo statement is still executed! This is because a Warning does not stop the script execution.

Now, let's run the same example with the require() function.

PHP code:

require("wrongFile.php");

echo "Hello World!";

?>

Error message:

Warning: require(wrongFile.php) [function.require]:

failed to open stream:

No such file or directory in C:\home\website\test.php on line 5

Fatal error: require() [function.require]:

Failed opening required 'wrongFile.php'

(include_path='.;C:\php5\pear')

in C:\home\website\test.php on line 5

The echo statement was not executed because the script execution stopped after the fatal error.

It is recommended to use the require() function instead of include(), because scripts should not continue executing if files are missing or misnamed.

Chapter 16

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:

$file=fopen("welcome.txt","r");

?>

The file may be opened in one of the following modes:

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:

$file=fopen("welcome.txt","r") or exit("Unable to open file!");

?>

Closing a File

The fclose() function is used to close an open file:

$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:

$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). "

";

  }

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:

$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.

Chapter 17

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:

enctype="multipart/form-data">
Filename:
 

Notice the following about the HTML form above:

• The enctype attribute of the
  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 tag specifies that the input should be possessed 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:

if ($_FILES["file"]["error"] > 0) { echo "Error: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; 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:

if (($_FILES["file"]["type"] == "image/gif") || ($_FILES["file"]["type"] == "image/jpeg") && ($_FILES["file"]["size"] <> { if ($_FILES["file"]["error"] > 0) { echo "Error: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; echo "Stored in: " . $_FILES["file"]["tmp_name"]; } } else { echo "Invalid file"; } ?>

---

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:

if (($_FILES["file"]["type"] == "image/gif") || ($_FILES["file"]["type"] == "image/jpeg") && ($_FILES["file"]["size"] <> { if ($_FILES["file"]["error"] > 0) { echo "Return Code: " . $_FILES["file"]["error"] . " "; } else { echo "Upload: " . $_FILES["file"]["name"] . " "; echo "Type: " . $_FILES["file"]["type"] . " "; echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb "; echo "Temp file: " . $_FILES["file"]["tmp_name"] . " "; if (file_exists("upload/" . $_FILES["file"]["name"])) { echo $_FILES["file"]["name"] . " already exists. "; } else { move_uploaded_file($_FILES["file"]["tmp_name"], "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.

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Chapter 18

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 for 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 tag.

Syntax

setcookie(name, value, expire, path, domain);

Example

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:

setcookie("user", "Alex Porter", time()+3600); ?>

Note: The value of the cookie is automatically URLencoded when sending the cookie, and automatically decoded when received (to prevent URLencoding, use setrawcookie() instead).

---

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:

// 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:

if (isset($_COOKIE["user"])) echo "Welcome " . $_COOKIE["user"] . "! "; else echo "Welcome guest! "; ?>

---

How to Delete a Cookie?

When deleting a cookie you should assure that the expiration date is in the past.

Delete example:

// 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:

Name: Age:

Retrieve the values in the "welcome.php" file like this:

Welcome .

You are  years old.

Chapter 19

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 tag:

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:

session_start();

// store session data

$_SESSION['views']=1;

?>

//retrieve session data

echo "Pageviews=". $_SESSION['views'];

?>

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:

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:

?>

You can also completely destroy the session by calling the session_destroy() function:

?>

Note: session_destroy() will reset your session and you will lose all your stored session data.

Chapter 20

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)

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 our PHP 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:

$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:

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: $subject",

  $message, "From: $email" );

  echo "Thank you for using our mail form";

  }

else

//if "email" is not filled out, display the form

  {

  echo "
  Email: 

  Subject: 

  Message:

  <o:p></o:p></span></pre><pre><span style="font-size: 8pt; color: black;"><span style="">  </span>

  
  ";

  }

?>

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

PHP Mail Reference

For more information about the PHP mail() function, visit our PHP Mail Reference.

Chapter 21

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:

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: $subject",

  $message, "From: $email" );

  echo "Thank you for using our mail form";

  }

else

//if "email" is not filled out, display the form

  {

  echo "
  Email: 

  Subject: 

  Message:

  <o:p></o:p></span></pre><pre><span style="font-size: 8pt; color: black;"><span style="">  </span>

  
  ";

  }

?>

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.com

%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:

function spamcheck($field)

  {

//eregi() performs a case insensitive regular expression match

  if(eregi("to:",$field) || eregi("cc:",$field)) 

    {

    return TRUE;

    }

  else

    {

    return FALSE;

    }

  }

//if "email" is filled out, send email

if (isset($_REQUEST['email']))

  {

  //check if the email address is invalid

  $mailcheck = spamcheck($_REQUEST['email']);

  if ($mailcheck==TRUE)

    {

    echo "Invalid input";

    }

  else

    { 

    //send email

    $email = $_REQUEST['email'] ; 

    $subject = $_REQUEST['subject'] ;

    $message = $_REQUEST['message'] ;

    mail("someone@example.com", "Subject: $subject",

    $message, "From: $email" );

    echo "Thank you for using our mail form";

    }

  }

else

//if "email" is not filled out, display the form

  {

  echo "
  Email: 

  Subject: 

  Message:

  <o:p></o:p></span></pre><pre><span style="font-size: 8pt; color: black;"><span style="">  </span>

  
  ";

  }

?>