PHP NOTES FOR BEGGINERS

PHP NOTES
PHP is a server scripting language, and a powerful tool for making dynamic
and interactive Web pages.
PHP is a widely-used, free, and efficient alternative to competitors such as
Microsoft's ASP.
Easy Learning with "Show PHP"
Our "Show PHP" tool makes it easy to learn PHP, it shows both the PHP source
code and the HTML output of the code.
Example
<!DOCTYPE html>
<html>
<body>
<?php
echo "My first PHP script!";
?>
</body>
</html>
My first PHP script!
INTRODUCTIONS
PHP scripts are executed on the server.
What You Should Already Know
Before you continue you should have a basic understanding of the following:
 HTML
 CSS
 JavaScript

If you want to study these subjects first, find the tutorials on our Home page.
What is PHP?
 PHP is an acronym for "PHP: Hypertext Preprocessor"
 PHP is a widely-used, open source scripting language
 PHP scripts are executed on the server
 PHP is free to download and use
PHP is an amazing and popular language!
It is powerful enough to be at the core of the biggest blogging system on the
web (WordPress)!
It is deep enough to run the largest social network (Facebook)!
It is also easy enough to be a beginner's first server side language!
What is a PHP File?
 PHP files can contain text, HTML, CSS, JavaScript, and PHP code
 PHP code are executed on the server, and the result is returned to the
browser as plain HTML
 PHP files have extension ".php"
What Can PHP Do?
 PHP can generate dynamic page content
 PHP can create, open, read, write, delete, and close files on the server
 PHP can collect form data
 PHP can send and receive cookies
 PHP can add, delete, modify data in your database
 PHP can be used to control user-access
 PHP can encrypt data
With PHP you are not limited to output HTML. You can output images, PDF files,
and even Flash movies. You can also output any text, such as XHTML and XML.

Why PHP?
 PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
 PHP is compatible with almost all servers used today (Apache, IIS, etc.)
 PHP supports a wide range of databases
 PHP is free. Download it from the official PHP resource: www.php.net
 PHP is easy to learn and runs efficiently on the server side
PHP 5 Installation
What Do I Need?
To start using PHP, you can:
 Find a web host with PHP and MySQL support
 Install a web server on your own PC, and then install PHP and MySQL
Use a Web Host With PHP Support
If your server has activated support for PHP you do not need to do anything.
Just create some .php files, place them in your web directory, and the server
will automatically parse them for you.
You do not need to compile anything or install any extra tools.
Because PHP is free, most web hosts offer PHP support.
Set Up PHP on Your Own PC
However, if your server does not support PHP, you must:
 install a web server

 install PHP
 install a database, such as MySQL
The official PHP website (PHP.net) has installation instructions for
PHP: http://php.net/manual/en/install.php
PHP 5 Syntax
❮ Previous Next ❯
A PHP script is executed on the server, and the plain HTML result is sent
back to the browser.
Basic PHP Syntax
A PHP script can be placed anywhere in the document.
A PHP script starts with <?php and ends with ?>:
<?php
// PHP code goes here
?>
The default file extension for PHP files is ".php".
A PHP file normally contains HTML tags, and some PHP scripting code.
Below, we have an example of a simple PHP file, with a PHP script that uses a
built-in PHP function "echo" to output the text "Hello World!" on a web page:
Example
<!DOCTYPE html>
<html>
<body>
<h1>My first PHP page</h1>

<?php
echo "Hello World!";
?>
</body>
</html>
My first PHP page
Hello World!
PHP 5 Variables
Variables are "containers" for storing information.
Creating (Declaring) PHP Variables
In PHP, a variable starts with the $ sign, followed by the name of the variable:
Example
<?php
$txt = "Hello world!";
$x = 5;
$y = 10.5;
After the execution of the statements above, the variable $txt will hold the
value Hello world!, the variable $x will hold the value 5, and the
variable $y will hold the value 10.5.
Note: When you assign a text value to a variable, put quotes around the value.
Note: Unlike other programming languages, PHP has no command for declaring
a variable. It is created the moment you first assign a value to it.
Think of variables as containers for storing data.

PHP Variables
A variable can have a short name (like x and y) or a more descriptive name
(age, carname, total_volume).
Rules for PHP variables:
 A variable starts with the $ sign, followed by the name of the variable
 A variable name must start with a letter or the underscore character
 A variable name cannot start with a number
 A variable name can only contain alpha-numeric characters and
underscores (A-z, 0-9, and _ )
 Variable names are case-sensitive ($age and $AGE are two different
variables)
Remember that PHP variable names are case-sensitive!
Output Variables
The PHP echo statement is often used to output data to the screen.
The following example will show how to output text and a variable:
Example
<?php
$txt = "W3Schools.com";
echo "I love $txt!";
?>
OUPUT= I love W3Schools.com!
Note: You will learn more about the echo statement and how to output data to
the screen in the next chapter.

PHP is a Loosely Typed Language
In the example above, notice that we did not have to tell PHP which data type
the variable is.
PHP automatically converts the variable to the correct data type, depending on
its value.
In other languages such as C, C++, and Java, the programmer must declare
the name and type of the variable before using it.
PHP Variables Scope
In PHP, variables can be declared anywhere in the script.
The scope of a variable is the part of the script where the variable can be
referenced/used.
PHP has three different variable scopes:
 local
 global
 static
Global and Local Scope
A variable declared outside a function has a GLOBAL SCOPE and can only be
accessed outside a function:
Example
<?php
$x = 5; // global scope
function myTest() {
// using x inside this function will generate an error
echo "<p>Variable x inside function is: $x</p>";
}

myTest();
echo "<p>Variable x outside function is: $x</p>";
?>
Run example »
A variable declared within a function has a LOCAL SCOPE and can only be
accessed within that function:
Example
<?php
function myTest() {
$x = 5; // local scope
echo "<p>Variable x inside function is: $x</p>";
}
myTest();
// using x outside the function will generate an error
echo "<p>Variable x outside function is: $x</p>";
?>
Run example »
You can have local variables with the same name in different functions, because
local variables are only recognized by the function in which they are declared.
PHP The global Keyword
The global keyword is used to access a global variable from within a function.
To do this, use the global keyword before the variables (inside the function):
Example
<?php
$x = 5;
$y = 10;
function myTest() {
global $x, $y;
$y = $x + $y;
}

myTest();
echo $y; // outputs 15
?>
Run example »
PHP also stores all global variables in an array called $GLOBALS[index].
The index holds the name of the variable. This array is also accessible from
within functions and can be used to update global variables directly.
The example above can be rewritten like this:
Example
<?php
$x = 5;
$y = 10;
function myTest() {
$GLOBALS['y'] = $GLOBALS['x'] + $GLOBALS['y'];
}
myTest();
echo $y; // outputs 15
?>
PHP The static Keyword
Normally, when a function is completed/executed, all of its variables are
deleted. However, sometimes we want a local variable NOT to be deleted. We
need it for a further job.
To do this, use the static keyword when you first declare the variable:
Example
<?php
function myTest() {
static $x = 0;
echo $x;
$x++;
}
myTest();

myTest();
myTest();
?>
Then, each time the function is called, that variable will still have the
information it contained from the last time the function was called.
Note: The variable is still local to the function.
PHP 5 echo and print Statements
In PHP there are two basic ways to get output: echo and print.
In this tutorial we use echo (and print) in almost every example. So, this
chapter contains a little more info about those two output statements.
PHP echo and print Statements
echo and print are more or less the same. They are both used to output data
to the screen.
The differences are small: echo has no return value while print has a return
value of 1 so it can be used in expressions. echo can take multiple parameters
(although such usage is rare) while print can take one argument. echo is
marginally faster than print.
The PHP echo Statement
The echo statement can be used with or without parentheses: echo or echo().
Display Text

The following example shows how to output text with the echo command
(notice that the text can contain HTML markup):
Example
<?php
echo "<h2>PHP is Fun!</h2>";
echo "Hello world!<br>";
echo "I'm about to learn PHP!<br>";
echo "This ", "string ", "was ", "made ", "with multiple parameters.";
?>
OUTPUT
PHP is Fun!
Hello world!
I'm about to learn PHP!
This string was made with multiple parameters.
Display Variables
The following example shows how to output text and variables with
the echo statement:
Example
<?php
$txt1 = "Learn PHP";
$txt2 = "W3Schools.com";
$x = 5;
$y = 4;
echo "<h2>" . $txt1 . "</h2>";
echo "Study PHP at " . $txt2 . "<br>";
echo $x + $y;
?>
OUTPUT
Learn PHP

Study PHP at W3Schools.com
9
The PHP print Statement
The print statement can be used with or without parentheses: print or print().
Display Text
The following example shows how to output text with the print command
(notice that the text can contain HTML markup):
Example
<?php
print "<h2>PHP is Fun!</h2>";
print "Hello world!<br>";
print "I'm about to learn PHP!";
?>
OUTPUT
PHP is Fun!
Hello world!
I'm about to learn PHP!
Display Variables
The following example shows how to output text and variables with
the print statement:
Example
<?php
$txt1 = "Learn PHP";
$txt2 = "W3Schools.com";
$x = 5;
$y = 4;
print "<h2>" . $txt1 . "</h2>";

print "Study PHP at " . $txt2 . "<br>";
print $x + $y;
?>
OUTPUT= Learn PHP
Study PHP at W3Schools.com
9
PHP Data Types
Variables can store data of different types, and different data types can do
different things.
PHP supports the following data types:
 String
 Integer
 Float (floating point numbers - also called double)
 Boolean
 Array
 Object
 NULL
 Resource
PHP String
A string is a sequence of characters, like "Hello world!".
A string can be any text inside quotes. You can use single or double quotes:
Example
<?php
$x = "Hello world!";
$y = 'Hello world!';
echo $x;
echo "<br>";

echo $y;
?>
Run example »
PHP Integer
An integer data type is a non-decimal number between -2,147,483,648 and
2,147,483,647.
Rules for integers:
 An integer must have at least one digit
 An integer must not have a decimal point
 An integer can be either positive or negative
 Integers can be specified in three formats: decimal (10-based),
hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed
with 0)
In the following example $x is an integer. The PHP var_dump() function returns
the data type and value:
Example
<?php
$x = 5985;
var_dump($x);
?>
PHP Float
A float (floating point number) is a number with a decimal point or a number in
exponential form.
In the following example $x is a float. The PHP var_dump() function returns the
data type and value:
Example
<?php
$x = 10.365;

var_dump($x);
?>
Run example »
PHP Boolean
A Boolean represents two possible states: TRUE or FALSE.
$x = true;
$y = false;
Booleans are often used in conditional testing. You will learn more about
conditional testing in a later chapter of this tutorial.
PHP Array
An array stores multiple values in one single variable.
In the following example $cars is an array. The PHP var_dump() function
returns the data type and value:
Example
<?php
$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>
Run example »
You will learn a lot more about arrays in later chapters of this tutorial.
PHP Object

An object is a data type which stores data and information on how to process
that data.
In PHP, an object must be explicitly declared.
First we must declare a class of object. For this, we use the class keyword. A
class is a structure that can contain properties and methods:
Example
<?php
class Car {
function Car() {
$this->model = "VW";
}
}
// create an object
$herbie = new Car();
// show object properties
echo $herbie->model;
?>
Run example »
You will learn more about objects in a later chapter of this tutorial.
PHP NULL Value
Null is a special data type which can have only one value: NULL.
A variable of data type NULL is a variable that has no value assigned to it.
Tip: If a variable is created without a value, it is automatically assigned a value
of NULL.
Variables can also be emptied by setting the value to NULL:
Example

<?php
$x = "Hello world!";
$x = null;
var_dump($x);
?>
Run example »
PHP Resource
The special resource type is not an actual data type. It is the storing of a
reference to functions and resources external to PHP.
A common example of using the resource data type is a database call.
We will not talk about the resource type here, since it is an advanced topic.
PHP 5 Strings
A string is a sequence of characters, like "Hello world!".
PHP String Functions
In this chapter we will look at some commonly used functions to manipulate
strings.
Get The Length of a String

The PHP strlen() function returns the length of a string.
The example below returns the length of the string "Hello world!":
Example
<?php
echo strlen("Hello world!"); // outputs 12
?>
Run example »
The output of the code above will be: 12.
Count The Number of Words in a String
The PHP str_word_count() function counts the number of words in a string:
Example
<?php
echo str_word_count("Hello world!"); // outputs 2
?>
Run example »
Reverse a String
The PHP strrev() function reverses a string:
Example

<?php
echo strrev("Hello world!"); // outputs !dlrow olleH
?>
Run example »
The output of the code above will be: !dlrow olleH.
Search For a Specific Text Within a String
The PHP strpos() function searches for a specific text within a string.
If a match is found, the function returns the character position of the first
match. If no match is found, it will return FALSE.
The example below searches for the text "world" in the string "Hello world!":
Example
<?php
echo strpos("Hello world!", "world"); // outputs 6
?>
Run example »
Tip: The first character position in a string is 0 (not 1).
Replace Text Within a String
The PHP str_replace() function replaces some characters with some other
characters in a string.
The example below replaces the text "world" with "Dolly":
Example

<?php
echo str_replace("world", "Dolly", "Hello world!"); // outputs Hello Dolly!
?>
Run example »
The output of the code above will be: Hello Dolly!
PHP 5 Constants
Constants are like variables except that once they are defined they cannot
be changed or undefined.
PHP Constants
A constant is an identifier (name) for a simple value. The value cannot be
changed during the script.
A valid constant name starts with a letter or underscore (no $ sign before the
constant name).
Note: Unlike variables, constants are automatically global across the entire
script.
Create a PHP Constant
To create a constant, use the define() function.
Syntax
define(name, value, case-insensitive)

Parameters:
 name: Specifies the name of the constant
 value: Specifies the value of the constant
 case-insensitive: Specifies whether the constant name should be case-
insensitive. Default is false
The example below creates a constant with a case-sensitive name:
Example
<?php
define("GREETING", "Welcome to W3Schools.com!");
echo GREETING;
?>
The example below creates a constant with a case-insensitive name:
Example
<?php
define("GREETING", "Welcome to W3Schools.com!", true);
echo greeting;
?>
Constants are Global
Constants are automatically global and can be used across the entire script.
The example below uses a constant inside a function, even if it is defined
outside the function:
Example
<?php
define("GREETING", "Welcome to W3Schools.com!");
function myTest() {
echo GREETING;
}

myTest();
?>
OUTPUT
Welcome to W3Schools.com!
Complete PHP String Reference
For a complete reference of all string functions, go to our complete PHP String
Reference.
The PHP string reference contains description and example of use, for each
function!
PHP Operators
Operators are used to perform operations on variables and values.
PHP divides the operators in the following groups:
 Arithmetic operators
 Assignment operators
 Comparison operators
 Increment/Decrement operators
 Logical operators
 String operators
 Array operators
PHP Arithmetic Operators
The PHP arithmetic operators are used with numeric values to perform common
arithmetical operations, such as addition, subtraction, multiplication etc.
Operator Name Example Result

+ Addition $x + $y Sum of $x and $y
- Subtraction $x - $y Difference of $x and $y
* Multiplication $x * $y Product of $x and $y
/ Division $x / $y Quotient of $x and $y
% Modulus $x % $y Remainder of $x divided by $y
** Exponentiation $x ** $y Result of raising $x to the $y'th power
(Introduced in PHP 5.6)
PHP Assignment Operators
The PHP assignment operators are used with numeric values to write a value to
a variable.
The basic assignment operator in PHP is "=". It means that the left operand
gets set to the value of the assignment expression on the right.
Assignment Same as... Description
x = y x = y The left operand gets set to the value of the expression

on the right
x += y x = x + y Addition
x -= y x = x - y Subtraction
x *= y x = x * y Multiplication
x /= y x = x / y Division
x %= y x = x % y Modulus
PHP Comparison Operators
The PHP comparison operators are used to compare two values (number or
string):
== Equal $x == $y Returns true if $x is equal to $y

=== Identical $x === $y Returns true if $x is equal to $y, and they
are of the same type
!= Not equal $x != $y Returns true if $x is not equal to $y
<> Not equal $x <> $y Returns true if $x is not equal to $y
!== Not identical $x !== $y Returns true if $x is not equal to $y, or they
are not of the same type
> Greater than $x > $y Returns true if $x is greater than $y
< Less than $x < $y Returns true if $x is less than $y
>= Greater than or
equal to
$x >= $y Returns true if $x is greater than or equal to
$y
<= Less than or
equal to
$x <= $y Returns true if $x is less than or equal to $y
PHP Increment / Decrement Operators
The PHP increment operators are used to increment a variable's value.
The PHP decrement operators are used to decrement a variable's value.

Operator Name Description
++$x Pre-increment Increments $x by one, then returns $x
$x++ Post-increment Returns $x, then increments $x by one
--$x Pre-decrement Decrements $x by one, then returns $x
$x-- Post-decrement Returns $x, then decrements $x by one
PHP Logical Operators
The PHP logical operators are used to combine conditional statements.
and And $x and $y True if both $x and $y are true
or Or $x or $y True if either $x or $y is true
xor Xor $x xor $y True if either $x or $y is true, but not
both

&& And $x && $y True if both $x and $y are true
|| Or $x || $y True if either $x or $y is true
! Not !$x True if $x is not true
PHP String Operators
PHP has two operators that are specially designed for strings.
. Concatenation $txt1 . $txt2 Concatenation of $txt1 and
$txt2
.= Concatenation
assignment
$txt1 .= $txt2 Appends $txt2 to $txt1
PHP Array Operators
The PHP array operators are used to compare arrays.

+ Union $x + $y Union of $x and $y
== Equality $x == $y Returns true if $x and $y have the same key/value
pairs
=== Identity $x ===
$y
Returns true if $x and $y have the same key/value
pairs in the same order and of the same types
!= Inequality $x != $y Returns true if $x is not equal to $y
<> Inequality $x <> $y Returns true if $x is not equal to $y
!== Non-
identity
$x !== $y Returns true if $x is not identical to $y
PHP 5 if...else...elseif Statements

Conditional statements are used to perform different actions based on
different conditions.
PHP Conditional Statements
Very often when you write code, you want to perform different actions for
different conditions. You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:
 if statement - executes some code if one condition is true
 if...else statement - executes some code if a condition is true and
another code if that condition is false
 if...elseif....else statement - executes different codes for more than
two conditions
 switch statement - selects one of many blocks of code to be executed
PHP - The if Statement
The if statement executes some code if one condition is true.
Syntax
if (condition) {
code to be executed if condition is true;
}
The example below will output "Have a good day!" if the current time (HOUR) is
less than 20:
Example
<?php
$t = date("H");
if ($t < "20") {
echo "Have a good day!";

}
?>
Run example »
PHP - The if...else Statement
The if....else statement executes some code if a condition is true and
another code if that condition is false.
Syntax
if (condition) {
code to be executed if condition is true;
} else {
code to be executed if condition is false;
}
The example below will output "Have a good day!" if the current time is less
than 20, and "Have a good night!" otherwise:
Example
<?php
$t = date("H");
if ($t < "20") {
} else {
echo "Have a good night!";
}
?>
Run example »
PHP - The if...elseif....else Statement

The if....elseif...else statement executes different codes for more than
two conditions.
Syntax
if (condition) {
code to be executed if this condition is true;
} elseif (condition) {
code to be executed if this condition is true;
} else {
code to be executed if all conditions are false;
}
The example below will output "Have a good morning!" if the current time is
less than 10, and "Have a good day!" if the current time is less than 20.
Otherwise it will output "Have a good night!":
Example
<?php
$t = date("H");
if ($t < "10") {
echo "Have a good morning!";
} elseif ($t < "20") {
} else {
echo "Have a good night!";
}
?>
Output
The hour (of the server) is 06, and will give the following message:
Have a good morning!
he switch statement is used to perform different actions based on different
conditions.
The PHP switch Statement

Use the switch statement to select one of many blocks of code to be
executed.
Syntax
switch (n) {
case label1:
code to be executed if n=label1;
break;
case label2:
break;
case label3:
break;
...
default:
code to be executed if n is different from all labels;
}
This is how it works: First we have a single expression n (most often a
variable), that is evaluated once. The value of the expression is then compared
with the values for each case in the structure. If there is a match, the block of
code associated with that case is executed. Use break to prevent the code from
running into the next case automatically. The default statement is used if no
match is found.
Example
<?php
$favcolor = "red";
switch ($favcolor) {
case "red":
echo "Your favorite color is red!";
break;
case "blue":
echo "Your favorite color is blue!";
break;
case "green":
echo "Your favorite color is green!";
break;
default:
echo "Your favorite color is neither red, blue, nor green!";

}
?>
OUTPUT
Your favorite color is red!
PHP 5 while Loops
PHP while loops execute a block of code while the specified condition is true.
PHP Loops
Often when you write code, you want the same block of code to run over and
over again in a row. Instead of adding several almost equal code-lines in a
script, we can use loops to perform a task like this.
In PHP, we have the following looping statements:
 while- loops through a block of code as long as the specified condition is
true
 do...while - loops through a block of code once, and then repeats the
loop as long as the specified 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 PHP while Loop
The while loop executes a block of code as long as the specified condition is
true.

Syntax
while (condition is true) {
code to be executed;
}
The example below first sets a variable $x to 1 ($x = 1). Then, the while loop
will continue to run as long as $x is less than, or equal to 5 ($x <= 5). $x will
increase by 1 each time the loop runs ($x++):
Example
<?php
$x = 1;
while($x <= 5) {
echo "The number is: $x <br>";
$x++;
}
?>
Run example »
The PHP do...while Loop
The do...while loop will always execute the block of code once, it will then
check the condition, and repeat the loop while the specified condition is true.
Syntax
do {
} while (condition is true);
The example below first sets a variable $x to 1 ($x = 1). Then, the do while
loop will write some output, and then increment the variable $x with 1. Then
the condition is checked (is $x less than, or equal to 5?), and the loop will
continue to run as long as $x is less than, or equal to 5:

Example
<?php
$x = 1;
do {
$x++;
} while ($x <= 5);
?>
OUTPUT
The number is: 1
The number is: 2
The number is: 3
The number is: 4
The number is: 5
Notice that in a do while loop the condition is tested AFTER executing the
statements within the loop. This means that the do while loop would execute
its statements at least once, even if the condition is false the first time.
The example below sets the $x variable to 6, then it runs the loop, and then
the condition is checked:
Example
<?php
$x = 6;
do {
$x++;
} while ($x <= 5);
?>
OUTPUT
The number is: 6
Run example »

The for loop and the foreach loop will be explained in the next chapter.
PHP 5 for Loops
PHP for loops execute a block of code a specified number of times.
The PHP for Loop
The for loop is used when you know in advance how many times the script
should run.
Syntax
for (init counter; test counter; increment counter) {
}
Parameters:
 init counter: Initialize the loop counter value
 test counter: Evaluated for each loop iteration. If it evaluates to TRUE,
the loop continues. If it evaluates to FALSE, the loop ends.
 increment counter: Increases the loop counter value
The example below displays the numbers from 0 to 10:
Example
<?php
for ($x = 0; $x <= 10; $x++) {
}
?>

Run example »
The PHP foreach Loop
The foreach loop works only on arrays, and is used to loop through each
key/value pair in an array.
Syntax
foreach ($array as $value) {
}
For every loop iteration, the value of the current array element is assigned to
$value and the array pointer is moved by one, until it reaches the last array
element.
The following example demonstrates a loop that will output the values of the
given array ($colors):
Example
<?php
$colors = array("red", "green", "blue", "yellow");
foreach ($colors as $value) {
echo "$value <br>";
}
?>
PHP 5 Functions
The real power of PHP comes from its functions; it has more than 1000 built-
in functions.

PHP User Defined Functions
Besides the built-in PHP functions, we can create our own functions.
A function is a block of statements that can be used repeatedly in a program.
A function will not execute immediately when a page loads.
A function will be executed by a call to the function.
Create a User Defined Function in PHP
A user-defined function declaration starts with the word function:
Syntax
function functionName() {
}
Note: A function name can start with a letter or underscore (not a number).
Tip: Give the function a name that reflects what the function does!
Function names are NOT case-sensitive.
In the example below, we create a function named "writeMsg()". The opening
curly brace ( { ) indicates the beginning of the function code and the closing
curly brace ( } ) indicates the end of the function. The function outputs "Hello
world!". To call the function, just write its name:
Example
<?php
function writeMsg() {
echo "Hello world!";
}

writeMsg(); // call the function
?>
Run example »
PHP Function Arguments
Information can be passed to functions through arguments. An argument is just
like a variable.
Arguments are specified after the function name, inside the parentheses. You
can add as many arguments as you want, just separate them with a comma.
The following example has a function with one argument ($fname). When the
familyName() function is called, we also pass along a name (e.g. Jani), and the
name is used inside the function, which outputs several different first names,
but an equal last name:
Example
<?php
function familyName($fname) {
echo "$fname Refsnes.<br>";
}
familyName("Jani");
familyName("Hege");
familyName("Stale");
familyName("Kai Jim");
familyName("Borge");
?>

OUTPUT
Jani Refsnes.
Hege Refsnes.
Stale Refsnes.
Kai Jim Refsnes.
Borge Refsnes.
Run example »
The following example has a function with two arguments ($fname and $year):
Example
<?php
function familyName($fname, $year) {
echo "$fname Refsnes. Born in $year <br>";
}
familyName("Hege", "1975");
familyName("Stale", "1978");
familyName("Kai Jim", "1983");
?>
OUTPUT
Hege Refsnes. Born in 1975
Stale Refsnes. Born in 1978
Kai Jim Refsnes. Born in 1983
Run example »
PHP Default Argument Value
The following example shows how to use a default parameter. If we call the
function setHeight() without arguments it takes the default value as argument:
Example

<?php
function setHeight($minheight = 50) {
echo "The height is : $minheight <br>";
}
setHeight(350);
setHeight(); // will use the default value of 50
setHeight(135);
setHeight(80);
?>
Run example »
PHP Functions - Returning values
To let a function return a value, use the return statement:
Example
<?php
function sum($x, $y) {
$z = $x + $y;
return $z;
}
echo "5 + 10 = " . sum(5, 10) . "<br>";
echo "7 + 13 = " . sum(7, 13) . "<br>";
echo "2 + 4 = " . sum(2, 4);
?>
Run example »
PHP 5 Arrays

An array stores multiple values in one single variable:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
Run example »
What is an Array?
An array is a special variable, which can hold more than one value at a time.
If you have a list of items (a list of car names, for example), storing the cars in
single variables could look like this:
$cars1 = "Volvo";
$cars2 = "BMW";
$cars3 = "Toyota";
However, what if you want to loop through the cars and find a specific one? And
what if you had not 3 cars, but 300?
The solution is to create an array!
An array can hold many values under a single name, and you can access the
values by referring to an index number.
Create an Array in PHP
In PHP, the array() function is used to create an array:
array();
In PHP, there are three types of arrays:

 Indexed arrays - Arrays with a numeric index
 Associative arrays - Arrays with named keys
 Multidimensional arrays - Arrays containing one or more arrays
PHP Indexed Arrays
There are two ways to create indexed arrays:
The index can be assigned automatically (index always starts at 0), like this:
or the index can be assigned manually:
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";
The following example creates an indexed array named $cars, assigns three
elements to it, and then prints a text containing the array values:
Example
<?php
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
Run example »
Get The Length of an Array - The count()
Function
The count() function is used to return the length (the number of elements) of
an array:

Example
<?php
echo count($cars);
?>
Run example »
Loop Through an Indexed Array
To loop through and print all the values of an indexed array, you could use
a for loop, like this:
Example
<?php
$arrlength = count($cars);
for($x = 0; $x < $arrlength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>
OUTPUT
Volvo
BMW
Toyota
Run example »
PHP Associative Arrays
Associative arrays are arrays that use named keys that you assign to them.

There are two ways to create an associative array:
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
or:
$age['Peter'] = "35";
$age['Ben'] = "37";
$age['Joe'] = "43";
The named keys can then be used in a script:
Example
<?php
echo "Peter is " . $age['Peter'] . " years old.";
?>
OUTPUT
Key=Peter, Value=35
Key=Ben, Value=37
Key=Joe, Value=43
Run example »
Loop Through an Associative Array
To loop through and print all the values of an associative array, you could use
a foreach loop, like this:
Example
<?php
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";

}
?>
Run example »
Multidimensional Arrays
Multidimensional arrays will be explained in the PHP advanced section.
Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array
Reference.
The reference contains a brief description, and examples of use, for each
function!
PHP 5 Sorting Arrays
The elements in an array can be sorted in alphabetical or numerical order,
descending or ascending.
PHP - Sort Functions For Arrays
In this chapter, we will go through the following PHP array sort functions:
 sort() - sort arrays in ascending order
 rsort() - sort arrays in descending order

 asort() - sort associative arrays in ascending order, according to the
value
 ksort() - sort associative arrays in ascending order, according to the key
 arsort() - sort associative arrays in descending order, according to the
value
 krsort() - sort associative arrays in descending order, according to the
key
Sort Array in Ascending Order - sort()
The following example sorts the elements of the $cars array in ascending
alphabetical order:
Example
<?php
sort($cars);
?>
Run example »
The following example sorts the elements of the $numbers array in ascending
numerical order:
Example
<?php
$numbers = array(4, 6, 2, 22, 11);
sort($numbers);
?>
Run example »
Sort Array in Descending Order - rsort()

The following example sorts the elements of the $cars array in descending
alphabetical order:
Example
<?php
rsort($cars);
?>
Run example »
The following example sorts the elements of the $numbers array in descending
numerical order:
Example
<?php
$numbers = array(4, 6, 2, 22, 11);
rsort($numbers);
?>
Run example »
Sort Array (Ascending Order), According to
Value - asort()
The following example sorts an associative array in ascending order, according
to the value:
Example
<?php
asort($age);
?>
Run example »

Sort Array (Ascending Order), According to Key
- ksort()
The following example sorts an associative array in ascending order, according
to the key:
Example
<?php
ksort($age);
?>
Run example »
Sort Array (Descending Order), According to
Value - arsort()
The following example sorts an associative array in descending order, according
to the value:
Example
<?php
arsort($age);
?>
Run example »
Sort Array (Descending Order), According to
Key - krsort()

The following example sorts an associative array in descending order, according
to the key:
Example
<?php
krsort($age);
?>
Run example »
Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array
Reference.
The reference contains a brief description, and examples of use, for each
function!
PHP 5 Global Variables - Superglobals
Superglobals were introduced in PHP 4.1.0, and are built-in variables that
are always available in all scopes.
PHP Global Variables - Superglobals
Several predefined variables in PHP are "superglobals", which means that they
are always accessible, regardless of scope - and you can access them from any
function, class or file without having to do anything special.

The PHP superglobal variables are:
 $GLOBALS
 $_SERVER
 $_REQUEST
 $_POST
 $_GET
 $_FILES
 $_ENV
 $_COOKIE
 $_SESSION
This chapter will explain some of the superglobals, and the rest will be explained
in later chapters.
PHP $GLOBALS
$GLOBALS is a PHP super global variable which is used to access global
variables from anywhere in the PHP script (also from within functions or
methods).
PHP stores all global variables in an array called $GLOBALS[index].
The index holds the name of the variable.
The example below shows how to use the super global variable $GLOBALS:
Example
<?php
$x = 75;
$y = 25;
function addition() {
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
addition();
echo $z;
?>
Run example »

In the example above, since z is a variable present within the $GLOBALS array,
it is also accessible from outside the function!
PHP $_SERVER
$_SERVER is a PHP super global variable which holds information about
headers, paths, and script locations.
The example below shows how to use some of the elements in $_SERVER:
Example
<?php
echo $_SERVER['PHP_SELF'];
echo "<br>";
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
echo $_SERVER['HTTP_REFERER'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];
?>
Run example »
The following table lists the most important elements that can go inside
$_SERVER:
Element/Code Description
$_SERVER['PHP_SELF'] Returns the filename of the currently executing script

$_SERVER['GATEWAY_INTERFACE'] Returns the version of the Common Gateway Interfac
the server is using
$_SERVER['SERVER_ADDR'] Returns the IP address of the host server
$_SERVER['SERVER_NAME'] Returns the name of the host server (such as
www.w3schools.com)
$_SERVER['SERVER_SOFTWARE'] Returns the server identification string (such as Apac
$_SERVER['SERVER_PROTOCOL'] Returns the name and revision of the information pro
as HTTP/1.1)
$_SERVER['REQUEST_METHOD'] Returns the request method used to access the page
POST)
$_SERVER['REQUEST_TIME'] Returns the timestamp of the start of the request (su
1377687496)
$_SERVER['QUERY_STRING'] Returns the query string if the page is accessed via a
string
$_SERVER['HTTP_ACCEPT'] Returns the Accept header from the current request

$_SERVER['HTTP_ACCEPT_CHARSET'] Returns the Accept_Charset header from the current
(such as utf-8,ISO-8859-1)
$_SERVER['HTTP_HOST'] Returns the Host header from the current request
$_SERVER['HTTP_REFERER'] Returns the complete URL of the current page (not re
because not all user-agents support it)
$_SERVER['HTTPS'] Is the script queried through a secure HTTP protocol
$_SERVER['REMOTE_ADDR'] Returns the IP address from where the user is viewin
current page
$_SERVER['REMOTE_HOST'] Returns the Host name from where the user is viewin
current page
$_SERVER['REMOTE_PORT'] Returns the port being used on the user's machine to
communicate with the web server
$_SERVER['SCRIPT_FILENAME'] Returns the absolute pathname of the currently exec
$_SERVER['SERVER_ADMIN'] Returns the value given to the SERVER_ADMIN direct
web server configuration file (if your script runs on a
host, it will be the value defined for that virtual host)

someone@w3schools.com)
$_SERVER['SERVER_PORT'] Returns the port on the server machine being used b
server for communication (such as 80)
$_SERVER['SERVER_SIGNATURE'] Returns the server version and virtual host name wh
added to server-generated pages
$_SERVER['PATH_TRANSLATED'] Returns the file system based path to the current scr
$_SERVER['SCRIPT_NAME'] Returns the path of the current script
$_SERVER['SCRIPT_URI'] Returns the URI of the current page
PHP $_REQUEST
PHP $_REQUEST is used to collect data after submitting an HTML form.
The example below shows a form with an input field and a submit button. When
a user submits the data by clicking on "Submit", the form data is sent to the file
specified in the action attribute of the <form> tag. In this example, we point to
this file itself for processing form data. If you wish to use another PHP file to
process form data, replace that with the filename of your choice. Then, we can
use the super global variable $_REQUEST to collect the value of the input field:
Example
<html>
<body>

<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// collect value of input field
$name = $_REQUEST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
Run example »
PHP $_POST
PHP $_POST is widely used to collect form data after submitting an HTML form
with method="post". $_POST is also widely used to pass variables.
The example below shows a form with an input field and a submit button. When
a user submits the data by clicking on "Submit", the form data is sent to the file
specified in the action attribute of the <form> tag. In this example, we point to
the file itself for processing form data. If you wish to use another PHP file to
process form data, replace that with the filename of your choice. Then, we can
use the super global variable $_POST to collect the value of the input field:
Example
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">

Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// collect value of input field
$name = $_POST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
Run example »
PHP $_GET
PHP $_GET can also be used to collect form data after submitting an HTML form
with method="get".
$_GET can also collect data sent in the URL.
Assume we have an HTML page that contains a hyperlink with parameters:
<html>
<body>
<a href="test_get.php?subject=PHP&web=W3schools.com">Test $GET</a>
</body>
</html>
When a user clicks on the link "Test $GET", the parameters "subject" and "web"
are sent to "test_get.php", and you can then access their values in
"test_get.php" with $_GET.

The example below shows the code in "test_get.php":
Example
<html>
<body>
<?php
echo "Study " . $_GET['subject'] . " at " . $_GET['web'];
?>
</body>
</html>
Run example »
Tip: You will learn more about $_POST and $_GET in the PHP Forms chapter.

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