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 (OSS)
- PHP is free to download and use
What is a PHP File?
- PHP files may 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"
What is MySQL?
- MySQL is a small database server
- MySQL is ideal for small and medium applications
- MySQL supports standard SQL
- MySQL compiles on a number of platforms
- MySQL is free to download and use
PHP + MySQL
- PHP combined with MySQL are cross-platform (means that you can develop in Windows and serve on a Unix platform)
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?
- Install an Apache server on a Windows or Linux machine
- Install PHP on a Windows or Linux machine
- Install MySQL on a Windows or Linux machine
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 ?>.
However, for maximum compatibility, we recommend that you use the standard form (<?php) rather than the shorthand form.
<?php
?>
|
Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:
<html>
<body>
<?php
echo "Hello World";
?>
</body>
</html>
|
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.<html>
<body>
<?php
//This is a comment
/*
This is
a comment
block
*/
?>
</body>
</html>
|
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:
<html>
<body>
<?php
$txt="Hello World";
echo $txt;
?>
</body>
</html>
|
<html>
<body>
<?php
$txt1="Hello World";
$txt2="1234";
echo $txt1 . " " . $txt2 ;
?>
</body>
</html>
|
Variable Naming Rules
- A variable name must start with a letter or an underscore "_"
- A variable name can only contain alpha-numeric characters and underscores (a-Z, 0-9, and _ )
- A variable name should not contain spaces. If a variable name should be more than one word, it should be separated with underscore ($my_string), or with capitalization ($myString)
PHP Operators
This section lists the different operators used in PHP.Arithmetic Operators
Operator
|
Description
|
Example
|
Result
|
+
|
Addition
|
x=2
x+2 |
4
|
-
|
Subtraction
|
x=2
5-x |
3
|
*
|
Multiplication
|
x=4
x*5 |
20
|
/
|
Division
|
15/5
5/2 |
3
2.5 |
%
|
Modulus (division remainder)
|
5%2
10%8 10%2 |
1
2 0 |
++
|
Increment
|
x=5
x++ |
x=6
|
--
|
Decrement
|
x=5
x-- |
x=4
|
Operator
|
Example
|
Is The Same As
|
=
|
x=y
|
x=y
|
+=
|
x+=y
|
x=x+y
|
-=
|
x-=y
|
x=x-y
|
*=
|
x*=y
|
x=x*y
|
/=
|
x/=y
|
x=x/y
|
%=
|
x%=y
|
x=x%y
|
Operator
|
Description
|
Example
|
==
|
is equal to
|
5==8 returns false
|
!=
|
is not equal
|
5!=8 returns true
|
>
|
is greater than
|
5>8 returns false
|
<
|
is less than
|
5<8 returns true
|
>=
|
is greater than or equal to
|
5>=8 returns false
|
<=
|
is less than or equal to
|
5<=8 returns true
|
Operator
|
Description
|
Example
|
&&
|
and
|
x=6
(x < 10 && y > 1)
returns truey=3 |
||
|
or
|
x=6
(x==5 || y==5) returns falsey=3 |
!
|
not
|
x=6
!(x==y) returns truey=3 |
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!":<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>
</body>
</html>
|
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
{
echo "Hello!<br />";
echo "Have a nice weekend!";
echo "See you on Monday!";
}
?>
</body>
</html>
|
The ElseIf Statement
If you want to execute some code if one of several conditions are true use the elseif statementSyntax
if (condition)
code to be executed if condition is true;
elseif (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
|
Example
The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
elseif ($d=="Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
?>
</body>
</html>
|
The Switch Statement
If you want to select one of many blocks of code to be executed, use the Switch statement.The switch statement is used to avoid long blocks of if..elseif..else code.
Syntax
switch (expression)
{
case label1:
code to be executed if expression = label1;
break;
case label2:
code to be executed if expression = label2;
break;
default:
code to be executed
if expression is different
from both label1 and label2;
}
|
Example
This is how it works:- A single expression (most often a variable) is evaluated once
- The value of the expression is compared with the values for each case in the structure
- If there is a match, the code associated with that case is executed
- After a code is executed, break is used to stop the code from running into the next case
- The default statement is used if none of the cases are true
<html>
<body>
<?php
switch ($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";
}
?>
</body>
</html>
|
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";
|
<?php
$names[0] = "Peter";
$names[1] = "Quagmire";
$names[2] = "Joe";
echo $names[1] . " and " . $names[2] .
" are ". $names[0] . "'s neighbors";
?>
|
Quagmire and Joe are Peter's neighbors
|
Associative Arrays
An associative array, each ID key is associated with a value.When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.
Example 1
In this example we use an array to assign ages to the different persons:$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";
|
<?php
$ages['Peter'] = "32";
$ages['Quagmire'] = "30";
$ages['Joe'] = "34";
echo "Peter are " . $ages['Peter'] . " years old.";
?>
|
Peter are 32 years old.
|
Multidimensional Arrays
In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.Example
In this example we create a multidimensional array, with automatically assigned ID keys:$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
)
)
|
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:<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 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:<html>
<body>
<?php
$i=0;
do
{
$i++;
echo "The number is " . $i . "<br />";
}
while ($i<5);
?>
</body>
</html>
|
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;
}
|
Example
The following example prints the text "Hello World!" five times:<html>
<body>
<?php
for ($i=1; $i<=5; $i++)
{
echo "Hello World!<br />";
}
?>
</body>
</html>
|
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:<html>
<body>
<?php
$arr=array("one", "two", "three");
foreach ($arr as $value)
{
echo "Value: " . $value . "<br />";
}
?>
</body>
</html>
|
Create a PHP Function
A function is a block of code that can be executed whenever we need it.Creating PHP functions:
- All functions start with the word "function()"
- Name the function - It should be possible to understand what the function does by its name. The name can start with a letter or underscore (not a number)
- Add a "{" - The function code starts after the opening curly brace
- Insert the function code
- Add a "}" - The function is finished by a closing curly brace
Example
A simple function that writes my name when it is called:<html>
<body>
<?php
function writeMyName()
{
echo "Kai Jim Refsnes";
}
writeMyName();
?>
</body>
</html>
|
Use a PHP Function
Now we will use the function in a PHP script:<html>
<body>
<?php
function writeMyName()
{
echo "Kai Jim Refsnes";
}
echo "Hello world!<br />";
echo "My name is ";
writeMyName();
echo ".<br />That's right, ";
writeMyName();
echo " is my name.";
?>
</body>
</html>
|
Hello world!
My name is Kai Jim Refsnes.
That's right, Kai Jim Refsnes is my name.
|
PHP Functions - Adding parameters
Our first function (writeMyName()) is a very simple function. It only writes a static string.To add more functionality to a function, we can add parameters. A parameter is just like a variable.
You may have noticed the parentheses after the function name, like: writeMyName(). The parameters are specified inside the parentheses.
Example 1
The following example will write different first names, but the same last name:<html>
<body>
<?php
function writeMyName($fname)
{
echo $fname . " Refsnes.<br />";
}
echo "My name is ";
writeMyName("Kai Jim");
echo "My name is ";
writeMyName("Hege");
echo "My name is ";
writeMyName("Stale");
?>
</body>
</html>
|
My name is Kai Jim Refsnes.
My name is Hege Refsnes.
My name is Stale Refsnes.
|
Example 2
The following function has two parameters:<html>
<body>
<?php
function writeMyName($fname,$punctuation)
{
echo $fname . " Refsnes" . $punctuation . "<br />";
}
echo "My name is ";
writeMyName("Kai Jim",".");
echo "My name is ";
writeMyName("Hege","!");
echo "My name is ";
writeMyName("Ståle","...");
?>
</body>
</html>
|
My name is Kai Jim Refsnes.
My name is Hege Refsnes!
My name is Ståle Refsnes...
|
PHP Functions - Return values
Functions can also be used to return values.Example
<html>
<body>
<?php
function add($x,$y)
{
$total = $x + $y;
return $total;
}
echo "1 + 16 = " . add(1,16)
?>
</body>
</html>
|
1 + 16 = 17
|
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:
<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>
|
The "welcome.php" file looks like this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
|
Welcome John.
You are 28 years old.
|
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.
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
<form action="welcome.php" method="get">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
|
welcome.php?name=Peter&age=37
|
Welcome <?php echo $_GET["name"]; ?>.<br />
You are <?php echo $_GET["age"]; ?> 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 <?php echo $_REQUEST["name"]; ?>.<br />
You are <?php echo $_REQUEST["age"]; ?> years old!
|
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
<form action="welcome.php" method="post">
Enter your name: <input type="text" name="name" />
Enter your age: <input type="text" name="age" />
<input type="submit" />
</form>
|
welcome.php
|
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old!
|
Why use $_POST?
- Variables sent with HTTP POST are not shown in the URL
- Variables have no length limit
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 <?php echo $_REQUEST["name"]; ?>.<br />
You are <?php echo $_REQUEST["age"]; ?> years old!
|
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>
|
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
|
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);
?>
|
Reading from a File
The feof() function is used to determine if the end of file is true.Note: You cannot read from files opened in w, a, and x mode!
if (feof($f))
echo "End of file";
|
Reading a Character
The fgetc() function is used to read a single character from a file.Note: After a call to this function the file pointer has moved to the next character.
Example
The example below reads a file character by character, until the end of file is true:<?php
$f=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($f))
{
$x=fgetc($f);
echo $x;
}
fclose($f);
?>
|
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 create cookies.Note: The setcookie() function must appear BEFORE the <html> tag.
Syntax
setcookie(name, value, expire, path, domain);
|
Example
The following example sets a cookie named "uname" - that expires after ten hours.<?php
setcookie("uname", $name, time()+36000);
?>
<html>
<body>
<p>
A cookie was set on this page! The cookie will be active when
the client has sent the cookie back to the server.
</p>
</body>
</html>
|
How to Retrieve a Cookie Value
When a cookie is set, PHP uses the cookie name as a variable.To access a cookie you just refer to the cookie name as a variable.
Tip: Use the isset() function to find out if a cookie has been set.
Example
The following example tests if the uname cookie has been set, and prints an appropriate message.<html>
<body>
<?php
if (isset($_COOKIE["uname"]))
echo "Welcome " . $_COOKIE["uname"] . "!<br />";
else
echo "You are not logged in!<br />";
?>
</body>
</html>
|
Server Side Includes
You can insert the content of one file into another file before the server executes it, with the require() function. The require() function is used to create functions, headers, footers, or elements that will be reused on multiple pages.This can save the developer a considerable amount of time. If all of the pages on your site have a similar header, you can include a single file containing the header into your pages. When the header needs updating, you only update the one page, which is included in all of the pages that use the header.
Example
The following example includes a header that should be used on all pages:<html>
<body>
<?php require("header.htm"); ?>
<p>
Some text
</p>
<p>
Some text
</p>
</body>
</html>
|
The mail() Function
The mail() function is used to send emails.Syntax
mail(to,subject,message,headers,parameters)
|
Parameter
|
Description
|
to
|
Required. Specifies the receiver / receivers of the email
|
subject
|
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 (\r\n)
|
parameters
|
Optional. Specifies an additional parameter to the sendmail
program (the one defined in the sendmail_path configuration setting). (i.e.
this can be used to set the envelope sender address when using sendmail with
the -f sendmail option)
|
PHP Simple Text E-Mail
The simplest way to send an email with PHP is to send a simple text email.This is a simple text email where we define the variables and send a mail:
<?php
$to = "someone@someplace.com";
$subject = "Test mail";
$message = "Hello! This is a simple text email message.";
$from = "someonelse@anotherplace.com";
$headers = "From: $from";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>
|
PHP Mail Form
Using PHP you can create a feedback form for your website. In this example it sends a text message to a specified e-mail.When using HTML forms with PHP, any form element in the HTML form will automatically be available to the PHP script.
This is how this example works:
- Check if the email input is set
- If it is not set (like when the page is first visited) it will output the HTML mail form
- If the email input is set (like after the form is filled out) it will send the mail from the form
- When submit is pressed after the form is filled out, the page reloads, sees that the email input is set, and sends the mail.
<html>
<body>
<?php
if (isset($_REQUEST['email']))
{
$email = $_REQUEST['email'] ;
$subject = $_REQUEST['subject'] ;
$message = $_REQUEST['message'] ;
mail( "someone@someplace.com", "Subject: $subject",
$message, "From: $email" );
echo "Thank you for using our mail form";
}
else
{
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>
|