Engr. F. Azam

An Internet Professional – Dedicated for SEO and Open Source Community

PHP4Novice


PHP TUTORIAL
By
Engr. F. Azam, B.Sc(CSE), CCNA.
Developing Dynamic Web Applications

—————————————————-

 

<!–[if !supportLists]–> <!–[endif]–>PHP Basics

<!–[if !supportLists]–> <!–[endif]–>Introduction

<!–[if !supportLists]–> <!–[endif]–>Installation

<!–[if !supportLists]–> <!–[endif]–>Syntax

<!–[if !supportLists]–> <!–[endif]–>Variables

<!–[if !supportLists]–> <!–[endif]–>Echo

<!–[if !supportLists]–> <!–[endif]–>Strings

<!–[if !supportLists]–> <!–[endif]–>Operators

<!–[if !supportLists]–> <!–[endif]–>Comments

<!–[if !supportLists]–> <!–[endif]–>Include File

<!–[if !supportLists]–> <!–[endif]–>Require

<!–[if !supportLists]–> <!–[endif]–>If Statement

<!–[if !supportLists]–> <!–[endif]–>If…Else

<!–[if !supportLists]–> <!–[endif]–>Elseif

<!–[if !supportLists]–> <!–[endif]–>Switch

<!–[if !supportLists]–> <!–[endif]–>Forms

<!–[if !supportLists]–> <!–[endif]–>Functions

<!–[if !supportLists]–> <!–[endif]–>Arrays

<!–[if !supportLists]–> <!–[endif]–>While Loop

<!–[if !supportLists]–> <!–[endif]–>For Loop

<!–[if !supportLists]–> <!–[endif]–>For Each

<!–[if !supportLists]–> <!–[endif]–>Do While

<!–[if !supportLists]–> <!–[endif]–>POST & GET

<!–[if !supportLists]–> <!–[endif]–>Magic Quotes

<!–[if !supportLists]–> <!–[endif]–>htmlentities

PHP Basics
Introduction

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:

<!–[if !supportLists]–> <!–[endif]–>Customize PHP scripts that you download, so that they better fit your needs.

<!–[if !supportLists]–> <!–[endif]–>Begin to understand the working model of PHP, so you may begin to design your own PHP projects.

<!–[if !supportLists]–> <!–[endif]–>Give you a solid base in PHP, so as to make you more valuable in the eyes of future employers.

PHP stands for PHP Hypertext Preprocessor. Inventor Rasmus Lerdorf.

PHP – What is it?

“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:

<!–[if !supportLists]–> <!–[endif]–>Reduce the time to create large websites.

<!–[if !supportLists]–> <!–[endif]–>Create a customized user experience for visitors based on information that you have gathered from them.

<!–[if !supportLists]–> <!–[endif]–>Open up thousands of possibilities for online tools. Check out PHP – HotScripts for examples of the great things that are possible with PHP.

<!–[if !supportLists]–> <!–[endif]–>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:

<!–[if !supportLists]–> <!–[endif]–>HTML – Know the syntax and especially HTML Forms.

<!–[if !supportLists]–> <!–[endif]–>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.

Installation

PHP – Necessary Setup

 

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

<!–[if !supportLists]–> <!–[endif]–>A web hosting account that supports the use of PHP web pages and grants you access to MySQL databases.

<!–[if !supportLists]–> <!–[endif]–>Have PHP and MySQL installed on your own computer. Read this lesson thorougly for more information on installing PHP.

Although MySQL is not absolutely necessary to use PHP, MySQL and PHP are wonderful complements to one another and some topics covered in this tutorial will require that you have MySQL access.

Installing PHP

For those who are experienced enough to do this yourself, simply head over to PHP.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 (http://www.php.net) based on the operating system that you are using.

<!–[if !supportLists]–> <!–[endif]–>PHP – Windows – Windows Installation Guide

<!–[if !supportLists]–> <!–[endif]–>PHP – Mac – Mac Installation Guide

<!–[if !supportLists]–> <!–[endif]–>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(http://www.mysql.com) Installation Guide for help on installing MySQL.

 

PHP Installation Troubles

If you have any installation troubles you may visit online communities for help on this common problem.

PHP Builder – A web forum for PHP users. (http://www.phpbuilders.com)

 

syntax

PHP – Syntax

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

SyntaxThe 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 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 function echo to write “Hello World!” and we will be talking in greater depth about this PHP function and many others 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.


variables

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.

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!

 

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.

<!–[if !supportLists]–>* <!–[endif]–>PHP variables must start with a letter or underscore “_”.

<!–[if !supportLists]–>* <!–[endif]–>PHP variables may only be comprised of alpha-numeric characters and underscores. a-z, A-Z, 0-9, or _ .

<!–[if !supportLists]–>* <!–[endif]–>Variables with more than one word should be separated with underscores. $my_variable

<!–[if !supportLists]–>* <!–[endif]–>Variables with more than one word can also be distinguished with capitalization. $myVariable.

 


ECHO

PHP – Echo

As you saw in the previous lesson, the PHP function echo is a means of outputting text to the web browser. Throughout your PHP career you will be using the echo function 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 the PHP echo function. 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! The echo function 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:

<!–[if !supportLists]–>* <!–[endif]–>Don’t use quotes inside your string

<!–[if !supportLists]–>* <!–[endif]–>Escape your quotes that are within the string with a slash. To escape a quote just place a slash directly before the quotation mark, i.e. \”

<!–[if !supportLists]–>* <!–[endif]–>Use single quotes (apostrophes) for quotes inside your string.

 

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

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 slash in front of it ( \” ). The slash 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 combine text strings and variables. By doing such a conjunction you save yourself from having to do a large number of echo statements. Variables and text strings are joined together with a period ( . ). The example below shows how to do such a combination.

PHP Code:

<?php

$my_string = “Hello Bob. My name is: “;

$newline = “<br />”;

echo $my_string.”Bobettta”.$newline;

echo “Hi, I’m Bob. Who are you? “.$my_string.$newline;

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

 

This combination can be done multiple times, as the example shows. This method of joining two or more strings together is called concatenation and we will talk more about this and other forms of string manipulation in our string lesson.


strings

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 place the string directly into a function.

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 function 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!

operators

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.

<!–[if !supportLists]–>* <!–[endif]–>Assignment Operators

<!–[if !supportLists]–>* <!–[endif]–>Arithmetic Operators

<!–[if !supportLists]–>* <!–[endif]–>Comparison Operators

<!–[if !supportLists]–>* <!–[endif]–>String Operators

<!–[if !supportLists]–>* <!–[endif]–>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 the increment to 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.


PHP Comments

PHP – Comments

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 by the browser.

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 “//” 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!”;

?>

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.

 

IF STATEMENT
PHP – If Statement
The PHP if statement is very similar to other programming languages use of if statement, but for those who are not familiar with it, picture the following:
Think about the decisions you make before you go to sleep. If you have something to do the next day, say go to work, school, or an appointment, then you will set your alarm clock to wake you up. Otherwise, you will sleep in as long as you like!
This simple kind of if/then statement is very common in every day life and also appears in programming quite often. Whenever you want to make a decision given that something is true (you have something to do tomorrow) and be sure that you take the appropriate action, you are using an if/then relationship.
The PHP If Statement
The if statement is necessary for most programming, thus it is important in PHP. Imagine that on January 1st you want to print out “Happy New Year!” at the top of your personal web page. With the use of PHP if statements you could have this process automated, months in advance, occurring every year on January 1st.
This idea of planning for future events is something you would never have had the opportunity of doing if you had just stuck with HTML.
If Statement Example
The “Happy New Year” example would be a little difficult for you to do right now, so let us instead start off with the basics of the if statement. The PHP if statement tests to see if a value is true, and if it is a segment of code will be executed. See the example below for the form of a PHP if statement.
PHP Code:
$my_name = “someguy”;
if ( $my_name == “someguy” ) {
echo “Your name is someguy!
“;
}
echo “Welcome to my homepage!”;
Display:
Your name is someguy!
Welcome to my homepage!
Did you get that we were comparing the variable $my_name with “someguy” to see if they were equal? In PHP you use the double equal sign (==) to compare values. Additionally, notice that because the if statement turned out to be true, the code segment was executed, printing out “Your name is someguy!”. Let’s go a bit more in-depth into this example to iron out the details.
We first set the variable $my_name equal to “someguy”.
We next used a PHP if statement to check if the value contained in the variable $my_name was equal to “someguy”
The comparison between $my_name and “someguy” was done with a double equal sign “==”, not a single equals”=”! A single equals is for assigning a value to a variable, while a double equals is for checking if things are equal.
Translated into english the PHP statement ( $my_name == “someguy” ) is ( $my_name is equal to “someguy” ).
$my_name is indeed equal to “someguy” so the echo statement is executed.
A False If Statement
Let us now see what happens when a PHP if statement is not true, in other words, false. Say that we changed the above example to:
PHP Code:
$my_name = “anotherguy”;
if ( $my_name == “someguy” ) {
echo “Your name is someguy!
“;
}
echo “Welcome to my homepage!”;
Display:
Welcome to my homepage!
Here the variable contained the value “anotherguy”, which is not equal to “someguy”. The if statement evaluated to false, so the code segment of the if statement was not executed. When used properly, the if statement is a powerful tool to have in your programming arsenal!

IF … Else statement

PHP – If … Else Conditional Statement

Has someone ever told you, “if you work hard, then you will succeed”? And what happens if you do not work hard? Well, you fail! This is an example of an if/else conditional statement.

<!–[if !supportLists]–>* <!–[endif]–>If you work hard then you will succeed.

<!–[if !supportLists]–>* <!–[endif]–>Else, if you do not work hard, then you will fail.

How does this translate into something useful for PHP developers? Well consider this:

Someone comes to your website and you want to ask this visitor her name if it is her first time coming to your site. With an if statement this is easy. Simply have a conditional statement to check, “are you visiting for the first time”. If the condition is true, then take them to the “Insert Your Name” page, else let her view the website as normal because you have already asked her for her name in the past.

If/Else an Example

Using these conditional statements can add a new layers of “cool” to your website. Here’s the basic form of an if/else statement in PHP.

PHP Code:

$number_three = 3;

if ( $number_three == 3 ) {

echo “The if statement evaluated to true”;

} else {

echo “The if statement evaluated to false”;

}

Display:

The if statement evaluated to true

This is a lot to digest in one sitting, so let us step through the code, line by line.

<!–[if !supportLists]–>* <!–[endif]–>We first made a PHP variable called $number_three and set it equal to 3.

<!–[if !supportLists]–>* <!–[endif]–>In this example we compared a variable to an integer value. To do such a comparison we use “==”, which in English means “Is Equal To”.

<!–[if !supportLists]–>* <!–[endif]–>$number_three is indeed Equal To 3 and so this statement will evaluate to true.

<!–[if !supportLists]–>* <!–[endif]–>All code that is contained between the opening curly brace “{” that follows the if statement and the closing curly brace “}” will be executed when the if statement is true.

<!–[if !supportLists]–>* <!–[endif]–>The code contained within the else segment will not used.

Execute Else Code with False

On the other hand, if the if statement was false, then the code contained in the else segment would have been executed. Note that the code within the if and else cannot both be executed, as the if statement cannot evaluate to both true and false at one time! Here is what would happen if we changed to $number_three to anything besides the number 3.

PHP Code:

$number_three = 421;

if ( $number_three == 3 ) {

echo “The if statement evaluated to true”;

} else {

echo “The if statement evaluated to false”;

}

Display:

The if statement evaluated to false

The variable was set to 421, which is not equal to 3 and if statement was false. As you can see, the code segment contained within the else was used in this case.


ELSEIF statement

PHP – ElseIf Statement

An if/else statement is great if you only need to check for one condition. However, what would you do if you wanted to check if your $employee variable was the company owner Bob, the Vice President Ms. Tanner, or a regular employee? To check for these different conditions you would need the elseif statement.

PHP – Elseif What is it?

An if statement is made up of the keyword “if” and a conditional statement (i.e. $name == “Ted”). Just like an if statement, an elseif statement also contains a conditional statement, but it must be preceded by an if statement. You cannot have an elseif statement without first having an if statement.

When PHP evaluates your If…elseif…else statement it will first see if the If statement is true. If that tests comes out false it will then check the first elseif statement. If that is false it will either check the next elseif statement, or if there are no more elseif statements, it will evaluate the else segment, if one exists (I don’t think I’ve ever used the word “if” so much in my entire life!). Let’s take a look at a real world example.

PHP – Using Elseif with If…Else

Let’s start out with the base case. Imagine we have a simpler version of the problem described above. We simply want to find out if the employee is the Vice President Ms. Tanner. We only need an if else statement for this part of the example.

PHP Code:

$employee = “Bob”;

if($employee == “Ms. Tanner”){

echo “Hello Ma’am”;

} else {

echo “Morning”;

}

Now, if we wanted to also check to see if the big boss Bob was the employee we need to insert an elseif clause.

 

PHP Code:

$employee = “Bob”;

if($employee == “Ms. Tanner”){

echo “Hello Ma’am”;

} elseif($employee == “Bob”){

echo “Good Morning Sir!”;

}else {

echo “Morning”;

}

Display:

Good Morning Sir!

PHP first checked to see if $employee was equal to “Ms. Tanner”, which evaluated to false. Next, PHP checked the first elseif statement. $employee did in fact equal “Bob” so the phrase “Good Morning Sir!” was printed out. If we wanted to check for more employee names we could insert more elseif statements!

Remember that an elseif statement cannot be used unless it is preceded by an if statement!


switch statement

PHP – Switch Statement

In the previous lessons we covered the various elements that make up an If Statement in PHP. However, there are times when an if statement is not the most efficient way to check for certain conditions.

For example we might have a variable that stores travel destinations and you want to pack according to this destination variable. In this example you might have 20 different locations that you would have to check with a nasty long block of If/ElseIf/ElseIf/ElseIf/… statements. This doesn’t sound like much fun to code, let’s see if we can do something different.

PHP Switch Statement: Speedy Checking

With the use of the switch statement you can check for all these conditions at once, and the great thing is that it is actually more efficient programming to do this. A true win-win situation!

The way the Switch statement works is it takes a single variable as input and then checks it against all the different cases you set up for that switch statement. Instead of having to check that variable one at a time, as it goes through a bunch of If Statements, the Switch statement only has to check one time.

PHP Switch Statement Example

In our example the single variable will be $destination and the cases will be: Las Vegas, Amsterdam, Egypt, Tokyo, and the Caribbean Islands.

PHP Code:

$destination = “Tokyo”;

echo “Traveling to $destination<br />”;

switch ($destination){

case “Las Vegas”:

echo “Bring an extra $500”;

break;

case “Amsterdam”:

echo “Bring an open mind”;

break;

case “Egypt”:

echo “Bring 15 bottles of SPF 50 Sunscreen”;

break;

case “Tokyo”:

echo “Bring lots of money”;

break;

case “Caribbean Islands”:

echo “Bring a swimsuit”;

break;

}

Display:

Traveling to Tokyo

Bring lots of money

The value of $destination was Tokyo, so when PHP performed the switch operating on $destination in immediately did a search for a case with the value of “Tokyo”. It found it and proceeded to execute the code that existed within that segment.

You might have noticed how each case contains a break; at the end of its code area. This break prevents the other cases from being executed. If the above example did not have any break statements then all the cases that follow Tokyo would have been executed as well. Use this knowledge to enhance the power of your switch statements!

The form of the switch statement is rather unique, so spend some time reviewing it before moving on. Note: Beginning programmers should always include the break; to avoid any unnecessary confusion.

PHP Switch Statement: Default Case

You may have noticed the lack of a place for code when the variable doesn’t match our condition. The if statement has the else clause and the switch statement has the default case.

It’s usually a good idea to always include the default case in all your switch statements. Below is a variation of our example that will result in none of the cases being used causing our switch statement to fall back and use the default case. Note: there is no case before default.

PHP Code:

$destination = “New York”;

echo “Traveling to $destination<br />”;

switch ($destination){

case “Las Vegas”:

echo “Bring an extra $500”;

break;

case “Amsterdam”:

echo “Bring an open mind”;

break;

case “Egypt”:

echo “Bring 15 bottles of SPF 50 Sunscreen”;

break;

case “Tokyo”:

echo “Bring lots of money”;

break;

case “Caribbean Islands”:

echo “Bring a swimsuit”;

break;

default:

echo “Bring lots of underwear!”;

break;

}

Display:

Traveling to New York

Bring lots of underwear!

 

HTML FORMS

Using PHP with HTML Forms

It is time to apply the knowledge you have obtained thus far and put it to real use. A very common application of PHP is to have an HTML form gather information from a website’s visitor and then use PHP to do process that information. In this lesson we will simulate a small business’s website that is implementing a very simple order form.

Imagine we are an art supply store that sells brushes, paint, and erasers. To gather order information from our prospective customers we will have to make a page with an HTML form to gather the customer’s order.

Note: This is an oversimplified example to educate you how to use PHP to process HTML form information. This example is not intended nor advised to be used on a real business website.

Creating the HTML Form

If you need a refresher on how to properly make an HTML form, check out the HTML Form Lesson before continuing on.

We first create an HTML form that will let our customer choose what they would like to purchase. This file should be saved as “order.html”

order.html Code:

<html><body>

<h4>Tizag Art Supply Order Form</h4>

<form>

<select>

<option>Paint</option>

<option>Brushes</option>

<option>Erasers</option>

</select>

Quantity: <input type=”text” />

<input type=”submit” />

</form>

</body></html>

Display:

<!–[if !vml]–><!–[endif]–>Tizag Art Supply Order Form

 

Remember to review HTML Forms if you do not understand any of the above HTML code. Next we must alter our HTML form to specify the PHP page we wish to send this information to. Also, we set the method to “post”.

order.html Code:

<html><body>

<h4>Tizag Art Supply Order Form</h4>

<form action=”process.php” method=”post”>

<select name=”item”>

<option>Paint</option>

<option>Brushes</option>

<option>Erasers</option>

</select>

Quantity: <input name=”quantity” type=”text” />

<input type=”submit” />

</form>

</body></html>

Now that our “order.html” is complete, let us continue on and create the “process.php” file which will process the HTML form information.

PHP Form Processor

We want to get the “item” and “quantity” inputs that we have specified in our HTML form. Using an associate array (this term is explained in the array lesson), we can get this information from the $_POST associative array.

The proper way to get this information would be to create two new variables, $item and $quantity and set them equal to the values that have been “posted”. The name of this file is “process.php”.

process.php Code:

<html><body>

<?php

$quantity = $_POST[‘quantity’];

$item = $_POST[‘item’];

 

echo “You ordered “. $quantity . ” ” . $item . “.<br />”;

echo “Thank you for ordering from Tizag Art Supplies!”;

 

?>

</body></html>

As you probably noticed, the name in $_POST[‘name’] corresponds to the name that we specified in our HTML form.

Now try uploading the “order.html” and “process.php” files to a PHP enabled server and test them out. If someone selected the item brushes and specified a quantity of 6, then the following would be displayed on “process.php”:

process.php Code:

You ordered 6 brushes.

Thank you for ordering from Tizag Art Supplies!

PHP & HTML Form Review

A lot of things were going on in this example. Let us step through it to be sure you understand what was going on.

1. We first created an HTML form “order.html” that had two input fields specified, “item” and “quantity”.

2. We added two attributes to the form tag to point to “process.php” and set the method to “post”.

3. We had “process.php” get the information that was posted by setting new variables equal to the values in the $_POST associative array.

4. We used the PHP echo function to output the customers order.

Remember, this lesson is only to teach you how to use PHP to get information from HTML forms. The example on this page should not be used for a real business.

PHP Functions

PHP – Functions

A function is just a name we give to a block of code that can be executed whenever we need it. This might not seem like that big of an idea, but believe me, when you understand and use functions you will be able to save a ton of time and write code that is much more readable!

For example, you might have a company motto that you have to display at least once on every webpage. If you don’t, then you get fired! Well, being the savvy PHP programmer you are, you think to yourself, “this sounds like a situation where I might need functions.”

Tip: Although functions are often thought of as an advanced topic for beginning programmers to learn, if you take it slow and stick with it, functions can be just minor speedbump in your programming career. So don’t give up if you functions confuse you at first!

Creating Your First PHP Function

When you create a function, you first need to give it a name, like myCompanyMotto. It’s with this function name that you will be able to call upon your function, so make it easy to type and understand.

The actual syntax for creating a function is pretty self-explanatory, but you can be the judge of that. First, you must tell PHP that you want to create a function. You do this by typing the keyword function followed by your function name and some other stuff (which we’ll talk about later).

Here is how you would make a function called myCompanyMotto. Note: We still have to fill in the code for myCompanyMotto.

PHP Code:

<?php

function myCompanyMotto(){

}

?>

Note: Your function name can start with a letter or underscore “_”, but not a number!

With a properly formatted function in place, we can now fill in the code that we want our function to execute. Do you see the curly braces in the above example “{ }”? These braces define where our function’s code goes. The opening curly brace “{” tells php that the function’s code is starting and a closing curly brace “}” tells PHP that our function is done!

We want our function to print out the company motto each time it’s called, so that sounds like it’s a job for the echo function!

PHP Code:

<?php

function myCompanyMotto(){

echo “We deliver quantity, not quality!<br />”;

}

?>

That’s it! You have written your first PHP function from scratch! Notice that the code that appears within a function is just the same as any other PHP code.

Using Your PHP Function

Now that you have completed coding your PHP function, it’s time to put it through a test run. Below is a simple PHP script. Let’s do two things: add the function code to it and use the function twice.

PHP Code:

<?php

echo “Welcome to Tizag.com <br />”;

echo “Well, thanks for stopping by! <br />”;

echo “and remember… <br />”;

?>

PHP Code with Function:

<?php

function myCompanyMotto(){

echo “We deliver quantity, not quality!<br />”;

}

echo “Welcome to Tizag.com <br />”;

myCompanyMotto();

echo “Well, thanks for stopping by! <br />”;

echo “and remember… <br />”;

myCompanyMotto();

?>

Display:

Welcome to Tizag.com

We deliver quantity, not quality!

Well, thanks for stopping by!

and remember…

We deliver quantity, not quality!

 

<!–[if !supportLists]–>* <!–[endif]–>Although this was a simple example, it’s important to understand that there is a lot going on and there are a lot of areas to make errors. When you are creating a function, follow these simple guidelines:

<!–[if !supportLists]–>* <!–[endif]–>Always start your function with the keyword function

<!–[if !supportLists]–>* <!–[endif]–>Remember that your function’s code must be between the “{” and the “}”

<!–[if !supportLists]–>* <!–[endif]–>When you are using your function, be sure you spell the function name correctly

<!–[if !supportLists]–>* <!–[endif]–>Don’t give up!

 

PHP Functions – Parameters

Another useful thing about functions is that you can send them information that the function can then use. Our first function myCompanyMotto isn’t all that useful because all it does, and ever will do, is print out a single, unchanging string.

However, if we were to use parameters, then we would be able to add some extra functionality! A parameter appears with the parentheses “( )” and looks just like a normal PHP variable. Let’s create a new function that creates a custom greeting based off of a person’s name.

Our parameter will be the person’s name and our function will concatenate this name onto a greeting string. Here’s what the code would look like.

PHP Code with Function:

<?php

function myGreeting($firstName){

echo “Hello there “. $firstName . “!<br />”;

}

?>

When we use our myGreeting function we have to send it a string containing someone’s name, otherwise it will break. When you add parameters, you also add more responsibility to you, the programmer! Let’s call our new function a few times with some common first names.

PHP Code:

<?php

function myGreeting($firstName){

echo “Hello there “. $firstName . “!<br />”;

}

myGreeting(“Jack”);

myGreeting(“Ahmed”);

myGreeting(“Julie”);

myGreeting(“Charles”);

?>

Display:

Hello there Jack!

Hello there Ahmed!

Hello there Julie!

Hello there Charles!

It is also possible to have multiple parameters in a function. To separate multiple parameters PHP uses a comma “,”. Let’s modify our function to also include last names.

PHP Code:

<?php

function myGreeting($firstName, $lastName){

echo “Hello there “. $firstName .” “. $lastName .”!<br />”;

}

myGreeting(“Jack”, “Black”);

myGreeting(“Ahmed”, “Zewail”);

myGreeting(“Julie”, “Roberts”);

myGreeting(“Charles”, “Schwab”);

?>

Display:

Hello there Jack Black!

Hello there Ahmed Zewail!

Hello there Julie Roberts!

Hello there Charles Schwab!

 

PHP Functions – Returning Values

Besides being able to pass functions information, you can also have them return a value. However, a function can only return one thing, although that thing can be any integer, float, array, string, etc. that you choose!

How does it return a value though? Well, when the function is used and finishes executing, it sort of changes from being a function name into being a value. To capture this value you can set a variable equal to the function. Something like:

$myVar = somefunction();

Let’s demonstrate this returning of a value by using a simple function that returns the sum of two integers.

PHP Code:

<?php

function mySum($numX, $numY){

$total = $numX + $numY;

return $total;

}

$myNumber = 0;

echo “Before the function, myNumber = “. $myNumber .”<br />”;

$myNumber = mySum(3, 4); // Store the result of mySum in $myNumber

echo “After the function, myNumber = ” . $myNumber .”<br />”;

?>

Display:

Before the function, myNumber = 0

After the function, myNumber = 7

 

When we first print out the value of $myNumber it is still set to the original value of 0. However, when we set $myNumber equal to the function mySum, $myNumber is set equal to mySum’s result. In this case, the result was 3 + 4 = 7, which was successfully stored into $myNumber and displayed in the second echo statement!

PHP Functions – Practice Makes Perfect

If you are new to programming, then this lesson might or might not seem like overkill. If you are having a hard time understanding lessons, the best piece of advice would be to do your best the first time, then be sure to come back tomorrow and next week and see if it makes anymore sense. Chances are, after going through this tutorial more than once, with breaks in between, this topic will be mastered.

 

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3 Responses to “PHP4Novice”

  1. Thanks

  2. bob said

    IngUgo hi nice site thx http://peace.com

  3. ruhulrabbi said

    Thanks for good writing.

    Thanks
    Rabbi

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