PHP tutorials

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php tutorial - learn php

If you want to learn the basics of PHP, then you've come to the right place. The goal of this tutorial is to teach you the basics of PHP so that you can:

php - what is it?

Taken directly from PHP's home, PHP.net, "PHP is an HTML-embedded scripting language. Much of its syntax is borrowed from C, Java and Perl with a couple of unique PHP-specific features thrown in. The goal of the language is to allow web developers to write dynamically generated pages quickly."

This is generally a good definition of PHP. However, it does contain a lot of terms you may not be used to. Another way to think of PHP is a powerful, behind the scenes scripting language that your visitors won't see!

When someone visits your PHP webpage, your web server processes the PHP code. It then sees which parts it needs to show to visitors(content and pictures) and hides the other stuff(file operations, math calculations, etc.) then translates your PHP into HTML. After the translation into HTML, it sends the webpage to your visitor's web browser.

php - what's it do?

It is also helpful to think of PHP in terms of what it can do for you. PHP will allow you to:

• Reduce the time to create large websites.
• Create a customized user experience for visitors based on information that you have gathered from them.
• Open up thousands of possibilities for online tools. Check out PHP - HotScriptsfor examples of the great things that are possible with PHP.
• Allow creation of shopping carts for e-commerce websites.

what you should know

Before starting this tutorial it is important that you have a basic understanding and experience in the following:

• HTML - Know the syntax and especially HTML Forms.
• Basic programming knowledge - This isn't required, but if you have any traditional programming experience it will make learning PHP a great deal easier.

tutorial overview

This tutorial is aimed at the PHP novice and will teach you PHP from the ground up. If you want a drive-through PHP tutorial this probably is not the right tutorial for you.

Remember, you should not try to plow through this tutorial in one sitting. Read a couple lessons, take a break, then do some more after the information has had some time to sink in.

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php - necessary setup

To begin working with PHP you must first have access to either of the following:

installing php

For those who are experienced enough to do this yourself, simply head over toPHP.net - Downloads and download the most recent version of PHP.

However, if you are like most of us, you will most likely want to follow a guide to installing PHP onto your computer. These guides are kindly provided by PHP.net based on the operating system that you are using.

• PHP - Windows - Windows Installation Guide
• PHP - Mac - Mac Installation Guide
• PHP - Linux - Linux Installation Guide

installing mysql

As we mentioned before, MySQL is not a requirement to use PHP, however they often go hand in hand.

Visit MySQL's MySQL Installation Guide for help on installing MySQL.

php - syntax

Before we talk about PHP's syntax, let us first define what syntax is referring to.

• Syntax - The rules that must be followed to write properly structured code.

PHP's syntax and semantics are similar to most other programming languages (C, Java, Perl) with the addition that all PHP code is contained with a tag, of sorts. All PHP code must be contained within the following...

PHP Code:

<?php
?>

or the shorthand PHP tag that requires shorthand support to be enabled
on your server...

<?
?>

If you are writing PHP scripts and plan on distributing them, we suggest that you use the standard form (which includes the ?php) rather than the shorthand form. This will ensure that your scripts will work, even when running on other servers with different settings.

how to save your php pages

If you have PHP inserted into your HTML and want the web browser to interpret it correctly, then you must save the file with a .php extension, instead of the standard .html extension. So be sure to check that you are saving your files correctly. Instead of index.html, it should be index.php if there is PHP code in the file.

example simple html & php page

Below is an example of one of the easiest PHP and HTML page that you can create and still follow web standards.

PHP and HTML Code:

<html>
<head>
<title>My First PHP Page</title>
</head>
<body>
<?php
echo "Hello World!";
?>
</body>
</html>

Display:

Hello World!

If you save this file (e.g. helloworld.php) and place it on PHP enabled server and load it up in your web browser, then you should see "Hello World!" displayed. If not, please check that you followed our example correctly.

We used the PHP command echo to write "Hello World!" and we will be talking in greater depth about how echo is special later on in this tutorial.

the semicolon!

As you may or may not have noticed in the above example, there was a semicolon after the line of PHP code. The semicolon signifies the end of a PHP statement and should never be forgotten. For example, if we repeated our "Hello World!" code several times, then we would need to place a semicolon at the end of each statement.

PHP and HTML Code:

<html>
<head>
<title>My First PHP Page</title>
</head>
<body>
<?php
echo "Hello World! ";
echo "Hello World! ";
echo "Hello World! ";
echo "Hello World! ";
echo "Hello World! ";
?>
</body>
</html>

Display:

Hello World! Hello World! Hello World! Hello World! Hello World!

white space

As with HTML, whitespace is ignored between PHP statements. This means it is OK to have one line of PHP code, then 20 lines of blank space before the next line of PHP code. You can also press tab to indent your code and the PHP interpreter will ignore those spaces as well.

PHP and HTML Code:

<html>
<head>
<title>My First PHP Page</title>
</head>
<body>
<?php
echo "Hello World!";        



	echo "Hello World!";


?>
</body>
</html>

Display:

Hello World!Hello World!

This is perfectly legal PHP code.

php - variables

If you have never had any programming, Algebra, or scripting experience, then the concept of variables might be a new concept to you. A detailed explanation of variables is beyond the scope of this tutorial, but we've included a refresher crash course to guide you.

A variable is a means of storing a value, such as text string "Hello World!" or the integer value 4. A variable can then be reused throughout your code, instead of having to type out the actual value over and over again. In PHP you define a variable with the following form:

• $variable_name = Value;

If you forget that dollar sign at the beginning, it will not work. This is a common mistake for new PHP programmers!

Note: Also, variable names are case-sensitive, so use the exact same capitalization when using a variable. The variables $a_number and $A_numberare different variables in PHP's eyes.

a quick variable example

Say that we wanted to store the values that we talked about in the above paragraph. How would we go about doing this? We would first want to make a variable name and then set that equal to the value we want. See our example below for the correct way to do this.

PHP Code:

<?php
$hello = "Hello World!";
$a_number = 4;
$anotherNumber = 8;
?>

Note for programmers: PHP does not require variables to be declared before being initialized.

php variable naming conventions

There are a few rules that you need to follow when choosing a name for your PHP variables.

• PHP variables must start with a letter or underscore "_".
• PHP variables may only be comprised of alpha-numeric characters and underscores. a-z, A-Z, 0-9, or _ .
• Variables with more than one word should be separated with underscores. $my_variable
• Variables with more than one word can also be distinguished with capitalization. $myVariable

php - echo

As you saw in the previous lesson, the PHP command echo is a means of outputting text to the web browser. Throughout your PHP career you will be using the echo command more than any other. So let's give it a solid perusal!

outputting a string

To output a string, like we have done in previous lessons, use PHP echo. You can place either a string variable or you can use quotes, like we do below, to create a string that the echo function will output.

PHP Code:

<?php
$myString = "Hello!";
echo $myString;
echo "<h5>I love using PHP!</h5>";
?>

Display:

Hello!

I love using PHP!

In the above example we output "Hello!" without a hitch. The text we are outputting is being sent to the user in the form of a web page, so it is important that we use proper HTML syntax!

In our second echo statement we use echo to write a valid Header 5 HTML statement. To do this we simply put the <h5> at the beginning of the string and closed it at the end of the string. Just because you're using PHP to make web pages does not mean you can forget about HTML syntax!

careful when echoing quotes!

It is pretty cool that you can output HTML with PHP. However, you must be careful when using HTML code or any other string that includes quotes!Echo uses quotes to define the beginning and end of the string, so you must use one of the following tactics if your string contains quotations:

• Don't use quotes inside your string
• Escape your quotes that are within the string with a backslash. To escape a quote just place a backslash directly before the quotation mark, i.e. \"
• Use single quotes (apostrophes) for quotes inside your string.

See our example below for the right and wrong use of echo:

PHP Code:

<?php
// This won't work because of the quotes around specialH5!
echo "<h5 class="specialH5">I love using PHP!</h5>";  

// OK because we escaped the quotes!
echo "<h5 class=\"specialH5\">I love using PHP!</h5>";  

// OK because we used an apostrophe '
echo "<h5 class='specialH5'>I love using PHP!</h5>";  
?>

If you want to output a string that includes quotations, either use an apostrophe ( ' ) or escape the quotations by placing a backslash in front of it ( \" ). The backslash will tell PHP that you want the quotation to be used within the string and NOT to be used to end echo's string.

echoing variables

Echoing variables is very easy. The PHP developers put in some extra work to make the common task of echoing all variables nearly foolproof! No quotations are required, even if the variable does not hold a string. Below is the correct format for echoing a variable.

PHP Code:

<?php
$my_string = "Hello Bob.  My name is: ";
$my_number = 4;
$my_letter = a;
echo $my_string;
echo $my_number;
echo $my_letter;
?>

Display:

Hello Bob. My name is: 4a

echoing variables and text strings

You can also place variables inside of double-quoted strings (e.g. "string here and a $variable"). By putting a variable inside the quotes (" ") you are telling PHP that you want it to grab the string value of that variable and use it in the string. The example below shows an example of this cool feature.

PHP Code:

<?php
$my_string = "Hello Bob.  My name is: ";
echo "$my_string Bobettta <br />";
echo "Hi, I'm Bob.  Who are you? $my_string <br />";
echo "Hi, I'm Bob.  Who are you? $my_string Bobetta";
?>

Display:

Hello Bob. My name is: Bobetta
Hi, I'm Bob. Who are you? Hello Bob. My name is:
Hi, I'm Bob. Who are you? Hello Bob. My name is: Bobetta

By placing variables inside a string you can save yourself some time and make your code easier to read, though it does take some getting used to. Remember to use double-quotes, single-quotes will not grab the value of the string. Single-quotes will just output the variable name to the string, like )$my_string), rather than (Hello Bob. My name is: ).

php echo - not a function

Echo is not a function, rather it is a language construct. When you usefunctions in PHP, they have a very particular form, which we will be going over later. For now, just know that echo is a special tool that you'll come to know and love!

php - strings

In the last lesson, PHP Echo, we used strings a bit, but didn't talk about them in depth. Throughout your PHP career you will be using strings a great deal, so it is important to have a basic understanding of PHP strings.

php - string creation

Before you can use a string you have to create it! A string can be used directly in a function or it can be stored in a variable. Below we create the exact same string twice: first storing it into a variable and in the second case we send the string directly to echo.

PHP Code:

$my_string = "Tizag - Unlock your potential!";
echo "Tizag - Unlock your potential!";
echo $my_string;

In the above example the first string will be stored into the variable $my_string, while the second string will be used in the echo and not be stored. Remember to save your strings into variables if you plan on using them more than once! Below is the output from our example code. They look identical just as we thought.

Display:

Tizag - Unlock your potential! Tizag - Unlock your potential!

php - string creation single quotes

Thus far we have created strings using double-quotes, but it is just as correct to create a string using single-quotes, otherwise known as apostrophes.

PHP Code:

$my_string = 'Tizag - Unlock your potential!';
echo 'Tizag - Unlock your potential!';
echo $my_string;

If you want to use a single-quote within the string you have to escape the single-quote with a backslash \ . Like this: \' !

PHP Code:

echo 'Tizag - It\'s Neat!';

php - string creation double-quotes

We have used double-quotes and will continue to use them as the primary method for forming strings. Double-quotes allow for many special escaped characters to be used that you cannot do with a single-quote string. Once again, a backslash is used to escape a character.

PHP Code:

$newline = "A newline is \n";
$return = "A carriage return is \r";
$tab = "A tab is \t";
$dollar = "A dollar sign is \$";
$doublequote = "A double-quote is \"";

Note: If you try to escape a character that doesn't need to be, such as an apostrophe, then the backslash will show up when you output the string.

These escaped characters are not very useful for outputting to a web page because HTML ignore extra white space. A tab, newline, and carriage return are all examples of extra (ignorable) white space. However, when writing to a file that may be read by human eyes these escaped characters are a valuable tool!

php - string creation heredoc

The two methods above are the traditional way to create strings in most programming languages. PHP introduces a more robust string creation tool calledheredoc that lets the programmer create multi-line strings without using quotations. However, creating a string using heredoc is more difficult and can lead to problems if you do not properly code your string! Here's how to do it:

PHP Code:

$my_string = <<<TEST
Tizag.com
Webmaster Tutorials
Unlock your potential!
TEST;

echo $my_string;

There are a few very important things to remember when using heredoc.

• Use <<< and some identifier that you choose to begin the heredoc. In this example we chose TEST as our identifier.
• Repeat the identifier followed by a semicolon to end the heredoc string creation. In this example that was TEST;
• The closing sequence TEST; must occur on a line by itself and cannot be indented!

Another thing to note is that when you output this multi-line string to a web page, it will not span multiple lines because we did not have any <br /> tags contained inside our string! Here is the output made from the code above.

Display:

Tizag.com Webmaster Tutorials Unlock your potential!

Once again, take great care in following the heredoc creation guidelines to avoid any headaches.

php - operators

In all programming languages, operators are used to manipulate or perform operations on variables and values. You have already seen the string concatenation operator "." in the Echo Lesson and the assignment operator "=" in pretty much every PHP example so far.

There are many operators used in PHP, so we have separated them into the following categories to make it easier to learn them all.

• Assignment Operators
• Arithmetic Operators
• Comparison Operators
• String Operators
• Combination Arithmetic & Assignment Operators

assignment operators

Assignment operators are used to set a variable equal to a value or set a variable to another variable's value. Such an assignment of value is done with the "=", or equal character. Example:

• $my_var = 4;
• $another_var = $my_var;

Now both $my_var and $another_var contain the value 4. Assignments can also be used in conjunction with arithmetic operators.

arithmetic operators

Operator	English	Example
+	Addition	2 + 4
-	Subtraction	6 - 2
*	Multiplication	5 * 3
/	Division	15 / 3
%	Modulus	43 % 10

PHP Code:

$addition = 2 + 4; 
$subtraction = 6 - 2; 
$multiplication = 5 * 3; 
$division = 15 / 3; 
$modulus = 5 % 2; 
echo "Perform addition: 2 + 4 = ".$addition."<br />"; 
echo "Perform subtraction: 6 - 2 = ".$subtraction."<br />"; 
echo "Perform multiplication:  5 * 3 = ".$multiplication."<br />"; 
echo "Perform division: 15 / 3 = ".$division."<br />"; 
echo "Perform modulus: 5 % 2 = " . $modulus 
	. ". Modulus is the remainder after the division operation has been performed.  
	In this case it was 5 / 2, which has a remainder of 1.";

Display:

Perform addition: 2 + 4 = 6
Perform subtraction: 6 - 2 = 4
Perform multiplication: 5 * 3 = 15
Perform division: 15 / 3 = 5
Perform modulus: 5 % 2 = 1. Modulus is the remainder after the division operation has been performed. In this case it was 5 / 2, which has a remainder of 1.

comparison operators

Comparisons are used to check the relationship between variables and/or values. If you would like to see a simple example of a comparison operator in action, check out our If Statement Lesson. Comparison operators are used inside conditional statements and evaluate to either true or false. Here are the most important comparison operators of PHP.
Assume: $x = 4 and $y = 5;

Operator	English	Example	Result
==	Equal To	$x == $y	false
!=	Not Equal To	$x != $y	true
<	Less Than	$x < $y	true
>	Greater Than	$x > $y	false
<=	Less Than or Equal To	$x <= $y	true
>=	Greater Than or Equal To	$x >= $y	false

string operators

As we have already seen in the Echo Lesson, the period "." is used to add two strings together, or more technically, the period is the concatenation operator for strings.

PHP Code:

$a_string = "Hello";
$another_string = " Billy";
$new_string = $a_string . $another_string;
echo $new_string . "!";

Display:

Hello Billy!

combination arithmetic & assignment operators

In programming it is a very common task to have to increment a variable by some fixed amount. The most common example of this is a counter. Say you want to increment a counter by 1, you would have:

• $counter = $counter + 1;

However, there is a shorthand for doing this.

• $counter += 1;

This combination assignment/arithmetic operator would accomplish the same task. The downside to this combination operator is that it reduces code readability to those programmers who are not used to such an operator. Here are some examples of other common shorthand operators. In general, "+=" and "-=" are the most widely used combination operators.

Operator	English	Example	Equivalent Operation
+=	Plus Equals	$x += 2;	$x = $x + 2;
-=	Minus Equals	$x -= 4;	$x = $x - 4;
*=	Multiply Equals	$x *= 3;	$x = $x * 3;
/=	Divide Equals	$x /= 2;	$x = $x / 2;
%=	Modulo Equals	$x %= 5;	$x = $x % 5;
.=	Concatenate Equals	$my_str.="hello";	$my_str = $my_str . "hello";

pre/post-increment & pre/post-decrement

This may seem a bit absurd, but there is even a shorter shorthand for the common task of adding 1 or subtracting 1 from a variable. To add one to a variable or "increment" use the "++" operator:

• $x++; Which is equivalent to $x += 1; or $x = $x + 1;

To subtract 1 from a variable, or "decrement" use the "--" operator:

• $x--; Which is equivalent to $x -= 1; or $x = $x - 1;

In addition to this "shorterhand" technique, you can specify whether you want to increment before the line of code is being executed or after the line has executed. Our PHP code below will display the difference.

PHP Code:

$x = 4;
echo "The value of x with post-plusplus = " . $x++;
echo "<br /> The value of x after the post-plusplus is " . $x;
$x = 4;
echo "<br />The value of x with with pre-plusplus = " . ++$x;
echo "<br /> The value of x after the pre-plusplus is " . $x;

Display:

The value of x with post-plusplus = 4
The value of x after the post-plusplus is = 5
The value of x with with pre-plusplus = 5
The value of x after the pre-plusplus is = 5

As you can see the value of $x++ is not reflected in the echoed text because the variable is not incremented until after the line of code is executed. However, with the pre-increment "++$x" the variable does reflect the addition immediately.

using comments in php

Comments in PHP are similar to comments that are used in HTML. The PHP comment syntax always begins with a special character sequence and all text that appears between the start of the comment and the end will be ignored.

In HTML a comment's main purpose is to serve as a note to you, the web developer or to others who may view your website's source code. However, PHP's comments are different in that they will not be displayed to your visitors. The only way to view PHP comments is to open the PHP file for editing. This makes PHP comments only useful to PHP programmers.

In case you forgot what an HTML comment looked like, see our example below.

HTML Code:

<!-- This is an HTML Comment -->

php comment syntax: single line comment

While there is only one type of comment in HTML, PHP has two types. The first type we will discuss is the single line comment. The single line comment tells the interpreter to ignore everything that occurs on that line to the right of the comment. To do a single line comment type "//" or "#" and all text to the right will be ignored by PHP interpreter.

PHP Code:

<?php
echo "Hello World!"; // This will print out Hello World!
echo "<br />Psst...You can't see my PHP comments!"; // echo "nothing";
// echo "My name is Humperdinkle!";
# echo "I don't do anything either";
?>

Display:

Hello World!
Psst...You can't see my PHP comments!

Notice that a couple of our echo statements were not evaluated because we commented them out with the single line comment. This type of line commenting is often used for quick notes about complex and confusing code or to temporarily remove a line of PHP code.

php comment syntax: multiple line comment

Similiar to the HTML comment, the multi-line PHP comment can be used to comment out large blocks of code or writing multiple line comments. The multiple line PHP comment begins with " /* " and ends with " */ ".

PHP Code:

<?php
/* This Echo statement will print out my message to the
the place in which I reside on.  In other words, the World. */
echo "Hello World!"; 
/* echo "My name is Humperdinkle!";
echo "No way! My name is Uber PHP Programmer!";
*/
?>

Display:

Hello World!

good commenting practices

One of the best commenting practices that I can recommend to new PHP programmers is....USE THEM!! So many people write complex PHP code and are either too lazy to write good comments or believe the commenting is not needed. However, do you really believe that you will remember exactly what you were thinking when looking at this code a year or more down the road?

Let the comments permeate your code and you will be a happier PHPer in the future. Use single line comments for quick notes about a tricky part in your code and use multiple line comments when you need to describe something in greater depth than a simple note.

php include

Without understanding much about the details of PHP, you can save yourself a great deal of time with the use of the PHP include command. include takes a file name and simply inserts that file's contents into the script that issued the includecommand.

an include example

Say we wanted to create a common menu file that all our pages will use. A common practice for naming files that are to be included is to use the ".php" extension. Since we want to create a common menu let's save it as "menu.php".

menu.php Code:

<html>
<body>
<a href="http://www.example.com/index.php">Home</a> - 
<a href="http://www.example.com/about.php">About Us</a> - 
<a href="http://www.example.com/links.php">Links</a> - 
<a href="http://www.example.com/contact.php">Contact Us</a> <br />

Save the above file as "menu.php". Now create a new file, "index.php" in the same directory as "menu.php". Here we will take advantage of the includecommand to add our common menu.

index.php Code:

<?php include("menu.php"); ?>
<p>This is my home page that uses a common menu to save me time when I add
new pages to my website!</p>
</body>
</html>

Display:

Home - About Us - Links - Contact Us

This is my home page that uses a common menu to save me time when I add new pages to my website!

And we would do the same thing for "about.php", "links.php", and "contact.php". Just think how terrible it would be if you had 15 or more pages with a common menu and you decided to add another web page to that site. You would have to go in and manually edit every single file to add this new page, but with include files you simply have to change "menu.php" and all your problems are solved. Avoid such troublesome occasions with a simple include file.

what do visitors see?

If we were to use the include command to insert a menu on each of our web pages, what would the visitor see if they viewed the source of "index.php"? Well, because the include command is pretty much the same as copying and pasting, the visitors would see:

View Source of index.php to a Visitor:

<html>
<body>
<a href="index.php">Home</a> - 
<a href="about.php">About Us</a> - 
<a href="links.php">Links</a> - 
<a href="contact.php">Contact Us</a> <br />
<p>This is my home page that uses a common menu to save me time when I add
new pages to my website!</p>
</body>
</html>

The visitor would actually see all the HTML code as one long line of HTML code, because we have not inserted any new line characters. We did some formatting above to make it easier to read. We will be discussing new line characters later.

include recap

The include command simply takes all the text that exists in the specified file and copies it into the file that uses the include command. Include is quite useful when you want to include the same PHP, HTML, or text segment on multiple pages of a website. The include command is used widely by PHP web developers. Like PHP Echo, include is not a function, but a language construct.

The next lesson will talk about a slight variation of the include command:require. It is often best to use the require command instead of the include command in your PHP Code. Read the next lesson to find out why!

php require

Just like the previous lesson, the require command is used to include a file into your PHP code. However there is one huge difference between the two commands, though it might not seem that big of a deal.

require vs include

When you include a file with the include command and PHP cannot find it you will see an error message like the following:

PHP Code:

<?php
include("noFileExistsHere.php");
echo "Hello World!";
?>

Display:

Warning: main(noFileExistsHere.php): failed to open stream: No such file or directory in/home/websiteName/FolderName/tizagScript.php on line 2Warning: main(): Failed opening 'noFileExistsHere.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in/home/websiteName/FolderName/tizagScript.php on line 2

Hello World!

Notice that our echo statement is still executed, this is because a Warning does not prevent our PHP script from running. On the other hand, if we did the same example but used the require statement we would get something like the following example.

PHP Code:

<?php
require("noFileExistsHere.php");
echo "Hello World!";
?>

Display:

Warning: main(noFileExistsHere.php): failed to open stream: No such file or directory in/home/websiteName/FolderName/tizagScript.php on line 2
Fatal error: main(): Failed opening required 'noFileExistsHere.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in/home/websiteName/FolderName/tizagScript.php on line 2

The echo statement was not executed because our script execution died after the require command returned a fatal error! We recommend that you use require instead of include because your scripts should not be executing if necessary files are missing or misnamed.