PHP - File Upload

PHP - File Upload

A very useful aspect of PHP is its ability to manage file uploads to your server. Allowing users to upload a file to your server opens a whole can of worms, so please be careful when enabling file uploads.

PHP - File Upload: HTML Form

Before you can use PHP to manage your uploads, you must first build an HTML form that lets
users select a file to upload. See our HTML Form
lesson for a more in-depth look at forms.

HTML Code:

<form enctype="multipart/form-data" action="uploader.php" method="POST">

<input type="hidden" name="MAX_FILE_SIZE" value="100000" />
Choose a file to upload: <input name="uploadedfile" type="file" /><br />
<input type="submit" value="Upload File" />
</form>

Here is a brief description of the important parts of the above code:

• enctype="multipart/form-data" - Necessary for our to-be-created PHP file to function properly.
• action="uploader.php" - The name of our PHP page that will be created, shortly.
• method="POST" - Informs the browser that we want to send information to the server using POST.
• input type="hidden" name="MA... - Sets the maximum allowable file size, in bytes, that can be uploaded. This
  safety mechanism is easily bypassed and we will show a solid backup solution in PHP. We have set the max file size to
  100KB in this example.
• input name="uploadedfile" - uploadedfile is how we will access the file in our PHP script.

Save that form code into a file and call it upload.html. If you view it in a browser it should look
like this:

PHP - File Truncate

PHP - File Truncate

As we have mentioned before, when you open a file for writing with the paramater 'w' it completely wipes all data from that file. This action is also referred to as "truncating" a file. Truncate literally means to shorten.

PHP - File Open: Truncate

To erase all the data from our testFile.txt file we need to open the file
for normal writing. All existing data within testFile.txt will be lost.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'w');
fclose($fh);

PHP - Truncate: Why Use It?

Truncating is most often used on files that contain data that will only be used
for a short time, before needing to be replaced. These type of files are most
often referred to as temporary files.

For example, you could create an online word processor that automatically saves
every thirty seconds. Every time it saves it would take all the data that existed
within some HTML form text box and save it to the server. This file, say tempSave.txt,
would be truncated and overwritten with new, up-to-date data every thirty seconds.


This might not be the most efficient program, but it is a nice usage of
truncate.

PHP - File Append

PHP - File Append

So far we have learned how to open, close, read, and write to a file. However, the ways in which we have written to a file so far have caused the data that was stored in the file to be deleted. If you want to append to a file, that is, add on to the existing data, then you need to open the file in append mode.

PHP - File Open: Append

If we want to add on to a file we need to open it up in append mode. The code below
does just that.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'a');

If we were to write to the file it would begin writing data at the end of the file.

PHP - File Write: Appending Data

Using the testFile.txt file we created in the File Write lesson
, we are going to append
on some more data.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'a') or die("can't open file");
$stringData = "New Stuff 1\n";
fwrite($fh, $stringData);
$stringData = "New Stuff 2\n";
fwrite($fh, $stringData);
fclose($fh);

You should noticed that the way we write data to the file is exactly the same as in the Write lesson.
The only thing that is different is that the file pointer is placed at the end of the file in append mode, so
all data is added to the end of the file.
The contents of the file testFile.txt would now look like this:

Contents of the testFile.txt File:

Floppy Jalopy

Pointy Pinto


New Stuff 1

New Stuff 2

PHP - Append: Why Use It?

The above example may not seem very useful, but appending data onto a file is
actually used everyday. Almost all web servers have a log of some sort. These various logs keep
track of all kinds of information, such as: errors, visitors, and even files that are installed on the machine.

A log is basically used to document events that occur over a period of time, rather than all at once. Logs: a perfect use for append!

PHP - File Delete

PHP - File Delete

You know how to create a file. You know how to open a file in an assortment of different ways. You even know how to read and write data from a file!

Now it's time to learn how to destroy (delete) files. In PHP you delete files
by calling the unlink function.

PHP - File Unlink

When you view the contents of a directory you can see all the files that exist in that
directory because the operating system or application that you are using displays a list of filenames. You can think of these filenames as links that
join the files to the directory you are currently viewing.
If you unlink a file, you are effectively
causing the system to forget about it or delete it!
Before you can delete (unlink) a file, you must first be sure that it is not
open in your program. Use the fclose function to close down an open file.

PHP - Unlink Function

Remember from the PHP File Create lesson that we created a file named

testFile.txt.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'w') or die("can't open file");
fclose($fh);

Now to delete testFile.txt we simply run a PHP script that is located
in the same directory. Unlink just needs to know the name of the file
to start working its destructive magic.

PHP Code:

$myFile = "testFile.txt";
unlink($myFile);

The testFile.txt should now be removed.

PHP - Unlink: Safety First!

With great power comes a slough of potential things you can mess up! When you
are performing the unlink function be sure that you are deleting the right file!

PHP - File Read

PHP - File Read

My apologies for taking so long to actually get to the point where you get information from files. In this lesson we will teach you how to read data from a file using various PHP functions.

PHP - File Open: Read

Before we can read information from a file we have to use the function fopen
to open the file for reading. Here's the code to read-open the file we created
in the PHP File Write lessons.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'r');

The file we created in the last lesson was named "testFile.txt". Your PHP script that you are writing should reside in the same
directory as "text.txt". Here are the contents of our file from File Write.

testFile.txt Contents:

Floppy Jalopy

Pointy Pinto

Now that the file is open, with read permissions enabled, we can get started!

PHP - File Read: fread Function

The fread function is the staple for getting data out of a file. The
function requires a file handle, which we have, and an integer to tell the
function how much data, in bytes, it is supposed to read.
One character is equal to one byte. If you wanted to read the first five characters
then you would use five as the integer.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'r');
$theData = fread($fh, 5);
fclose($fh);
echo $theData;

Display:

Flopp

The first five characters from the testFile.txt file are now stored inside
$theData. You could echo this string, $theData, or write it to another file.

If you wanted to read all the data from the file, then you need to get the
size of the file. The filesize function returns the length of a file, in bytes,
which is just what we need! The filesize function requires the name of the file that is to be sized up.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'r');
$theData = fread($fh, filesize($myFile));
fclose($fh);
echo $theData;

Display:

Floppy Jalopy Pointy Pinto

Note: It is all on one line because our "testFile.txt" file did not have a <br /> tag to
create an HTML line break.
Now the entire contents of the testFile.txt file is stored in the string variable

$theData.

PHP - File Read: gets Function

PHP also lets you read a line of data at a time from a file with the gets function. This can or cannot
be useful to you, the programmer. If you had separated your data with new lines
then you could read in one segment of data at a time with the gets function.


Lucky for us our "testFile.txt" file is separated by new lines and
we can utilize this function.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'r');
$theData = fgets($fh);
fclose($fh);
echo $theData;

testFile.txt Contents:

Floppy Jalopy

The fgets function searches for the first occurrence of "\n" the
newline character. If you did not write newline characters to your file
as we have done in File Write,
then this function might not work the way you expect it to.

PHP - File Write

PHP - File Write

Now that you know how to open and close a file, lets get on to the most useful part of file manipulation, writing! There is really only one main function that is used to write and it's logically called fwrite.

PHP - File Open: Write

Before we can write information to our test file we have to use the function fopen
to open the file for writing.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'w');

PHP - File Write: fwrite Function

We can use php to write to a text file. The fwrite function allows
data to be written to any type of file. Fwrite's first
parameter is the file handle and its second parameter is the string of data that is to
be written. Just give the function those two bits of information and you're good to go!

Below we are writing a couple of names into our test file testFile.txt and separating
them with a carriaged return.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'w') or die("can't open file");
$stringData = "Bobby Bopper\n";
fwrite($fh, $stringData);
$stringData = "Tracy Tanner\n";
fwrite($fh, $stringData);
fclose($fh);

The $fh variable contains the file handle for testFile.txt.
The file handle knows the current file pointer, which for writing, starts out at the beginning of the file.
We wrote to the file testFile.txt twice. Each time we wrote to the file
we sent the string $stringData that first contained Bobby Bopper and second contained

Tracy Tanner. After we finished writing we closed the file using the fclose function.


If you were to open the testFile.txt file in NOTEPAD it would look like this:

Contents of the testFile.txt File:

Bobby Bopper


Tracy Tanner

PHP - File Write: Overwriting

Now that testFile.txt contains some data we can demonstrate what happens
when you open an existing file for writing. All the data contained in the file
is wiped clean and you start with an empty file. In this example we open our existing
file testFile.txt and write some new data into it.

PHP Code:

$myFile = "testFile.txt";
$fh = fopen($myFile, 'w') or die("can't open file");
$stringData = "Floppy Jalopy\n";
fwrite($fh, $stringData);
$stringData = "Pointy Pinto\n";
fwrite($fh, $stringData);
fclose($fh);

If you now open the testFile.txt file you will see that Bobby and Tracy
have both vanished, as we expected, and only the data we just wrote is present.

Contents of the testFile.txt File:

Floppy Jalopy

Pointy Pinto

In the next lesson we will show you how to get information out of a file by using PHP's
read data functions!

PHP - File Close

PHP - File Close

The next logical step after you have opened a file and finished your business with it is to close that file down. You don't want an open file running around on your server taking up resources and causing mischief!

PHP - File Close Description

In PHP it is not system critical to close all your files after using them because the
server will close all files after the PHP code finishes execution. However the programmer
is still free to make mistakes (i.e. editing a file that you accidentally forgot to close). You should close
all files after you have finished with them because it's a good programming practice and because we told you to!

PHP - File Close Function

In a previous tutorial, we had a call to the function fclose to close down a file after we
were done with it. Here we will repeat that example and discuss the importance of closing a file.

PHP Code:

$ourFileName = "testFile.txt";
$ourFileHandle = fopen($ourFileName, 'w') or die("can't open file");
fclose($ourFileHandle);

The function fclose requires the file handle that we want to close down. In our example
we set our variable "$fileHandle" equal to the file handle returned by the fopen function.


After a file has been closed down with fclose it is impossible to read, write or append
to that file unless it is once more opened up with the fopen function.

PHP - File Open

PHP - File Open

In the previous lesson we used the function fopen to create a new file. In this lesson we will be going into the details of this important function and see what it has to offer.

PHP - Different Ways to Open a File

For many different technical reasons, PHP requires you to specify your intentions when you
open a file. Below are the three basic ways to open a file and the corresponding character that
PHP uses.

• Read: 'r'

Open a file for read only use. The file pointer begins at the front of the file.

• Write: 'w'

Open a file for write only use. In addition, the data in the file is erased and you
will begin writing data at the beginning of the file. This is also called truncating a file, which we will
talk about more in a later lesson. The file pointer begins at the start of the file.

• Append: 'a'

Open a file for write only use. However, the data in the file is preserved and you begin will
writing data at the end of the file. The file pointer begins at the end of the file.


A file pointer is PHP's way of remembering its location in a file. When you open a file for reading, the file pointer
begins at the start of the file.
This makes sense because you will usually be reading data from the front of the file.

However, when you
open a file for appending, the file pointer is at the end of the file, as you most likely will be appending data at the end of the file.
When you use reading or writing functions they begin at the location specified by the file pointer.

PHP - Explanation of Different Types of fopen

These three basic ways to open a file have distinct purposes. If you want to get information out of a file, like
search an e-book for the occurrences of "cheese", then you would open the file for read only.

If you wanted to
write a new file, or overwrite an existing file, then you would want to open the file with the "w" option. This would
wipe clean all existing data within the file.

If you wanted to add the latest order to your "orders.txt" file, then you would want to open it to append the data
on to the end. This would be the "a" option.

PHP - File Open: Advanced

There are additional ways to open a file. Above we stated the standard ways to open a file. However, you can open
a file in such a way that reading and writing is allowable! This combination is done by placing a plus sign "+" after the file mode character.

• Read/Write: 'r+'

Opens a file so that it can be read from and written to. The file pointer is at the beginning of the file.

• Write/Read: 'w+'

This is exactly the same as r+, except that it deletes all information in the file when the file is opened.

• Append: 'a+'

This is exactly the same as r+, except that the file pointer is at the end of the file.

PHP - File Open: Cookie Cutter

Below is the correct form for opening a file with PHP. Replace the (X) with
one of the options above (i.e. r, w, a, etc).

Pseudo PHP Code:

$ourFileName = "testFile.txt";
$fh = fopen($ourFileName, 'X') or die("Can't open file");
fclose($fh);

PHP - File Open: Summary

You can open a file in many different ways. You can delete everything and begin writing on a clean slate, you can add to existing data, and you
can simply read information from a file. In later lessons we will go into greater detail on how each of these different ways to open a file is used
in the real world and give some helpful examples.

PHP - File Create

PHP - File Create

Before you can do anything with a file it has to exist! In this lesson you will learn how to create a file using PHP.

PHP - Creating Confusion

In PHP, a file is created using a command that is also used to open files.
It may seem a little confusing, but we'll try to clarify this conundrum.

In PHP the fopen function is used to open files. However, it can also create

a file if it does not find the file specified in the function call. So if you use fopen on a file
that does not exist, it will create it, given that you open the file for writing or appending (more on this later).

PHP - How to Create a File

The fopen function needs two important pieces of information to operate correctly. First,
we must supply it with the name of the file that we want it to open. Secondly, we must tell the function
what we plan on doing with that file (i.e. read from the file, write information, etc).
Since we want to create a file, we must supply a file name and tell PHP that we want to write
to the file. Note: We have to tell PHP we are writing to the file, otherwise it will not create a new file.

PHP Code:

$ourFileName = "testFile.txt";
$ourFileHandle = fopen($ourFileName, 'w') or die("can't open file");
fclose($ourFileHandle);

The file "testFile.txt" should be created in the same directory where this PHP code resides. PHP will see that
"testFile.txt" does not exist and will create it after running this code. There's a lot of information in those three lines of code, let's make sure you understand it.

1. $ourFileName = "testFile.txt";
   Here we create the name of our file, "testFile.txt" and store it into a PHP String variable $ourFileName.
   
   
2. $ourFileHandle = fopen($ourFileName, 'w') or die("can't open file");
   This bit of code actually has two parts. First we use the function fopen and give it two arguments: our file name and we inform
   PHP that we want to write by passing the character "w".
   Second, the fopen function returns what is called a file handle, which will allow us to manipulate the file. We save
   the file handle into the $ourFileHandle variable. We will talk more about file handles later on.
   
   
3. fclose($ourFileHandle);
   We close the file that was opened. fclose takes the file handle that is to be closed. We will talk more about this more in the file closing lesson.
   

PHP - Permissions

If you are trying to get this program to run and you are having errors, you might want to check that
you have granted your PHP file access to write information to the hard drive. Setting permissions
is most often done with the use of an FTP program to execute a command called CHMOD. Use CHMOD to
allow the PHP file to write to disk, thus allowing it to create a file.

In the near future Tizag.com will have a more in-depth tutorial on how to use CHMOD to set
file permissions.

PHP - Files

PHP - Files

Manipulating files is a basic necessity for serious programmers and PHP gives you a great deal of tools for creating, uploading, and editing files.

This section of the PHP tutorial is completely dedicated to how PHP can interact with files. After completing this section you should have a solid understanding of all types of file manipulation in PHP!

PHP - Files: Be Careful

When you are manipulating files you must be very careful because you can do a lot of damage if you do something wrong. Common errors include editing the wrong file, filling a hard-drive with garbage data, and accidentally deleting a file's contents.

It is our hope that you will be able to avoid these and other slipups after reading this tutorial. However, we know that there are so many places where code can take a wrong turn, so we urge you to take extra care when dealing with files in PHP.

PHP - Files: Overview

The presentation of the file lessons will begin with how to create, open, and close a file. After establishing those basics, we will then cover other important file tasks, such as: read, write, append, truncate, and uploading files with PHP.

PHP htmlentities Function

PHP htmlentities Function

Whenever you allow your users to submit text to your website, you need to be careful that you don't leave any security holes open for malicious users to exploit. If you are ever going to allow user submitted text to be visible by the public you should consider using the htmlentities function to prevent them from running html code and scripts that may be harmful to your visitors.

PHP - Converting HTML into Entities

The htmlentities function takes a string and returns the same string with
HTML converted into HTML entities.
For example, the string "<script>" would be converted to "&lt;script&gt;".

By converting the < and > into entities, it prevents the browser from using it
as an HTML element and it prevents the code from running if you were to display some user's
input on your website.

This may seem a little complicated, but if you think of the way a browser works, in separate stages,
it becomes a little easier. Let's look at the way the function htmlentities changes the
data at three different levels: in PHP, in raw HTML and in the web browser. The sample
string is a bad script that will redirect visitors to the malicious user's own website.

PHP Code:

// An imaginary article submission from a bad user
//  it will redirect anyone to example.com if the code is run in a browser
$userInput = "I am going to hax0r your site, hahaha!
 <script type='text/javascript'>

 window.location = 'http://www.example.com/'
 </script>'";
 
//Lets make it safer before we use it
$userInputEntities = htmlentities($userInput);

//Now we can display it
echo $userInputEntities;

The HTML output of the above script would be as follows:

Safe Raw HTML Code:

I am going to hax0r your site, hahaha!
 <script type='text/javascript'>
 window.location = 'http://www.example.com/'
 </script>'

If we had not used htmlentities to convert any HTML code into safe entities, this is
what the raw HTML code would be and it would have redirect a visitor to example.com.

Dangerous Raw HTML Code:

I am going to hax0r your site, hahaha!
 <script type='text/javascript'>
 window.location = 'http://www.example.com/'
 </script>'

Those two HTML code examples are what you would see if you were to view source on the web page.
However, if you were just viewing the output normally in your browser you would
see the following.

Safe Display:

I am going to hax0r your site, hahaha!
<script type='text/javascript'>
window.location = 'http://www.example.com/'
</script>'

Dangerous Display:

You'd see whatever spammer site that the malicious user had sent you to. Probably
some herbal supplement site or weight loss pills would be displayed.

When Would You Use htmlentities?

Anytime you allow users to submit content to your website, that other visitors can see, you should
consider removing the ability to let them use HTML. Although this will remove a lot of cool things that
your users can do, like making heavily customized content, it will prevent your site from
a lot of common attacks. With some custom coding you can just remove specific tags
from running, but that is beyond the scope of this lesson.

Just remember, that when allowing users to submit content to your site you are also
giving them access to your website. Be sure you take the proper precautions.

PHP - Magic Quotes

PHP - Magic Quotes

Prior to PHP 6 there was a feature called magic quotes that was created to help protect newbie programmers from writing bad form processing code. Magic quotes would automatically escape risky form data that might be used for SQL Injection with a backslash \. The characters escaped by PHP include: quote ', double quote ", backslash \ and NULL characters.

However, this newbie protection proved to cause more problems than it solved and is not
in PHP 6. If your PHP version is any version before 6 then you should use this lesson
to learn more about how magic quotes can affect you.

Magic Quotes - Are They Enabled?

First things first, you need to check to see if you have magic quotes enabled on you server.
The get_magic_quotes_gpc function will return a 0 (off) or a 1 (on). These boolean values
will fit nicely into an if statement where 1 is true and 0 is false.

PHP Code:

if(get_magic_quotes_gpc())
 echo "Magic quotes are enabled";
else
 echo "Magic quotes are disabled";

Display:

Magic quotes are enabled

If you received the message "Magic quotes are enabled" then you should definitely
continue reading this lesson, if not feel free to learn about it in case you
are developing for servers that might have quotes on or off.

Magic Quotes in Action

Now lets make a simple form processor to show how machines with magic quotes
enabled will escape those potentially risky characters. This form submits to itself, so
you only need to make one file, "magic-quotes.php" to test it out.

magic-quotes.php Code:

<?php
echo "Altered Text: ".$_POST['question'];
?>

<form method='post'>

Question: <input type='text' name='question'/><br />
<input type='submit'>

</form>

This simple form will display to you what magic quotes is doing. If you were to
enter and submit the string: Sandy said, "It's a beautiful day outside and I like to use \'s."
You would receive the following output.

Display:

Altered Text: Sandy said, \"It\'s a beautiful day outside and I like to use \\\'s.\"

Question:

Magic quotes did a number on that string, didn't it? Notice that
there is a backslash before all of those risky characters we talked about earlier.
After magic quotes:

• A backslash \ becomes \\
• A quote ' becomes \'
• A double-quote " becomes \"

Now say that you wanted to remove the escaping that magic quotes puts in, you have two options:
disable magic quotes or strip the backslashes magic quotes adds.

Removing Backslashes - stripslashes()

Before you use PHP's backslash removal function stripslashes it's smart
to add some magic quote checking like our "Are They Enabled?" section above. This way
you won't accidentally be removing slashes that are legitimate in the future if
your PHP's magic quotes setting changes in the future.

magic-quotes.php Code:

<?php
echo "Removed Slashes: ";

// Remove those slashes
if(get_magic_quotes_gpc())
 echo stripslashes($_POST['question']);
else
 echo $_POST['question'];
 
?>

<form method='post'>
Question: <input type='text' name='question'/><br />
<input type='submit'>

</form>

Our new output for our string containing risky characters would now be:

Display:

Removed Slashes: Sandy said, "It's a beautiful day outside and I like to use \'s."

Question:

PHP - POST & GET

PHP - POST & GET

Recall from the PHP Forms Lesson where we used an HTML form and sent it to a PHP web page for processing. In that lesson we opted to use the the post method for submitting, but we could have also chosen the get method. This lesson will review both transferring methods.

POST - Review

In our PHP Forms Lesson we
used the post method. This is what the pertinent line of HTML code looked like:

HTML Code Excerpt:

<form action="process.php" method="post">
<select name="item">
...
<input name="quantity" type="text" />

This HTML code specifies that the form data will be submitted to the "process.php" web
page using the POST method. The way that PHP does this is to store all the "posted"
values into an associative array called "$_POST". Be sure to take notice the names
of the form data names, as they represent the keys in the "$_POST" associative array.

Now that you know about associative arrays,
the PHP code from "process.php" should make a litte more sense.

PHP Code Excerpt:

$quantity = $_POST['quantity'];
$item = $_POST['item'];

The form names are used as the keys in the associative array, so be
sure that you never have two input items in your HTML form that have the same name. If you do, then
you might see some problems arise.

PHP - GET

As we mentioned before, the alternative to the post method is get. If
we were to change our HTML form to the get method, it would look like this:

HTML Code Excerpt:

<form action="process.php" method="get">
<select name="item">
...
<input name="quantity" type="text" />

The get method is different in that it passes the variables along
to the "process.php" web page by appending them onto the end of the URL. The URL, after clicking submit,
would have this added on to the end of it:

"?item=##&quantity=##"

The question mark "?" tells the browser that the following items are variables. Now that we changed
the method of sending information on "order.html", we must change the "process.php" code
to use the "$_GET" associative array.

PHP Code Excerpt:

$quantity = $_GET['quantity'];
$item = $_GET['item'];

After changing the array name the script will function properly. Using
the get method displays the variable information to your visitor, so be sure
you are not sending password information or other sensitive items with the get method.
You would not want your visitors seeing something they are not supposed to!

Security Precautions

Whenever you are taking user input and using you need to be sure that the input is safe. If you are going to insert the data into a MySQL database, then you should be sure you have thought about preventing MySQL Injection. If you are going to make a user's input available to the public, then you should think about PHP htmlentities.

PHP - Do While Loop

PHP - Do While Loop

A "do while" loop is a slightly modified version of the while loop. If you recal from one of the previous lessons on While Loops the conditional statement is checked comes back true then the code within the while loop is executed. If the conditional statement is false then the code within the loop is not executed.

PHP - While Loop and Do While Loop Contrast

A simple example that illustrates the difference between these two loop types is
a conditional statement that is always false. First the while loop:

PHP Code:

$cookies = 0;
while($cookies > 1){
 echo "Mmmmm...I love cookies! *munch munch munch*";
} 

Display:

As you can see, this while loop's conditional statement failed (0 is not greater than 1), which means the code
within the while loop was not executed. Now, can you guess what will happen with
a do-while loop?

PHP Code:

$cookies = 0;
do {
 echo "Mmmmm...I love cookies! *munch munch munch*";
} while ($cookies > 1);

Display:

Mmmmm...I love cookies! *munch munch munch*

The code segment "Mmmm...I love cookies!" was executed even though the conditional
statement was false. This is because a do-while loop first do's and secondly checks the

while condition!

Chances are you will not need to use a do while loop in most of your PHP programming, but it
is good to know it's there!

PHP - For Loop

PHP - For Loop

The for loop is simply a while loop with a bit more code added to it. The common tasks that are covered by a for loop are:

Set a counter variable to some initial value.

Check to see if the conditional statement is true.

Execute the code within the loop.

Increment a counter at the end of each iteration through the loop.

The for loop allows you to define these steps in one easy line of code.
It may seem to have a strange form, so pay close attention to the syntax used!

For Loop Example

Let us take the example from the while loop lesson and see how
it could be done in a for loop. The basic structure of the for loop is as
follows:

Pseudo PHP Code:

for ( initialize a counter; conditional statement; increment a counter){
 do this code;
}

Notice how all the steps of the loop are taken care of in the for loop
statement. Each step is separated by a semicolon: initiliaze counter, conditional statement, and the
counter increment. A semicolon is needed because these are separate expressions. However, notice
that a semicolon is not needed after the "increment counter" expression.
Here is the example of the brush prices done with a for loop .

PHP Code:

$brush_price = 5; 

echo "<table border=\"1\" align=\"center\">";
echo "<tr><th>Quantity</th>";
echo "<th>Price</th></tr>";
for ( $counter = 10; $counter <= 100; $counter += 10) {
 echo "<tr><td>";
 echo $counter;
 echo "</td><td>";
 echo $brush_price * $counter;
 echo "</td></tr>";
}
echo "</table>";

Display:

Quantity	Price
10	50
20	100
30	150
40	200
50	250
60	300
70	350
80	400
90	450
100	500

It is important to note that both the for loop and while loop
implementation of the price chart table are both OK at getting the job done. However,
the for loop is somewhat more compact and would be preferable in this situation. In
later lessons we will see where the while loop should be used instead of the for loop.

PHP For Each Loop

Imagine that you have an associative array that you want to iterate through. PHP provides an easy way to use every element of an array with the Foreach statement.

In plain english this statement will do the following:

• For each item in the specified array execute this code.

While a For Loop and
While Loop will continue
until some condition fails, the For Each loop will continue until
it has gone through every item in the array.

PHP For Each: Example

We have an associative array that stores the names of people in our
company as the keys with the values being their age. We want
to know how old everyone is at work so we use a Foreach loop to print
out everyone's name and age.

PHP Code:

$employeeAges;
$employeeAges["Lisa"] = "28";
$employeeAges["Jack"] = "16";
$employeeAges["Ryan"] = "35";
$employeeAges["Rachel"] = "46";
$employeeAges["Grace"] = "34";

foreach( $employeeAges as $key => $value){
 echo "Name: $key, Age: $value <br />";
}

Display:

Name: Lisa, Age: 28

Name: Jack, Age: 16

Name: Ryan, Age: 35


Name: Rachel, Age: 46

Name: Grace, Age: 34

The syntax of the foreach statement is a little strange, so let's talk about it some.

Foreach Syntax: $something as $key => $value

This crazy statement roughly translates into: For each element of the
$employeeAges associative array I want to refer to the key as $key and the value as $value.

The operator "=>" represents the relationship between a key and value. You can imagine that
the key points => to the value. In our example we named the key $key and the value $value.
However, it might be easier to think of it as $name and $age. Below our example does this and notice how the output
is identical because we only changed the variable names that refer to the keys and values.

PHP Code:

$employeeAges;
$employeeAges["Lisa"] = "28";
$employeeAges["Jack"] = "16";
$employeeAges["Ryan"] = "35";
$employeeAges["Rachel"] = "46";
$employeeAges["Grace"] = "34";

foreach( $employeeAges as $name => $age){
 echo "Name: $name, Age: $age <br />";
}

Display:

Name: Lisa, Age: 28

Name: Jack, Age: 16


Name: Ryan, Age: 35

Name: Rachel, Age: 46

Name: Grace, Age: 34

PHP - While Loop

PHP - While Loop

Repetitive tasks are always a burden to us. Deleting spam email, sealing 50 envelopes, and going to work are all examples of tasks that are repeated. The nice thing about programming is that you can avoid such repetitive tasks with a little bit of extra thinking. Most often these repetitive tasks are conquered in the loop.

The idea of a loop is to do something over and over again until the task
has been completed. Before we show a real example of when you might need one,
let's go over the structure of the PHP while loop.

Simple While Loop Example

The function of the while loop is to do a task over and over as long
as the specified conditional statement is true. This logical check is the same
as the one that appears in a PHP if statement to determine if it is true or false.
Here is the basic structure of a PHP while loop:

Pseudo PHP Code:

while ( conditional statement is true){
 //do this code;
}

This isn't valid PHP code, but it displays how the while loop is structured.
Here is the break down of how a while loop functions when your script is executing:

1. The conditional statement is checked. If it is true, then (2) occurs. If it is false, then (4) occurs.
2. The code within the while loop is executed.
3. The process starts again at (1). Effectively "looping" back.
4. If the conditional statement is false, then the code within is not executed and there is no more looping. The code following
   the while loop is then executed like normal.

A Real While Loop Example

Imagine that you are running an art supply store. You would
like to print out the price chart for number of brushes and total cost.
You sell brushes at a flat rate, but would like to display how much
different quantities would cost. This will save your customers from having to
do the mental math themselves.
You know that a while loop would be perfect for this repetitive and boring task.
Here is how to go about doing it.

Pseudo PHP Code:

$brush_price = 5; 
$counter = 10;

echo "<table border=\"1\" align=\"center\">";
echo "<tr><th>Quantity</th>";
echo "<th>Price</th></tr>";
while ( $counter <= 100 ) {
 echo "<tr><td>";
 echo $counter;
 echo "</td><td>";
 echo $brush_price * $counter;
 echo "</td></tr>";
 $counter = $counter + 10;
}
echo "</table>";

Display:

Quantity	Price
10	50
20	100
30	150
40	200
50	250
60	300
70	350
80	400
90	450
100	500

Pretty neat, huh? The loop created a new table row and its respective entries
for each quantity, until our counter variable grew past the size of 100. When it
grew past 100 our conditional statement failed and the loop stopped being used. Let's review
what is going on.

1. We first made a $brush_price and $counter variable and
   set them equal to our desired values.
2. The table was set up with the beginning table tag and the table headers.
3. The while loop conditional statement was checked, and $counter (10) was indeed
   smaller or equal to 100.
4. The code inside the while loop was executed, creating a new table row for the price
   of 10 brushes.
5. We then added 10 to $counter to bring the value to 20.
6. The loop started over again at step 3, until $counter grew larger than 100.
7. After the loop had completed, we ended the table.

You may have noticed that we placed slashes
infront the quotations in the first echo statement. You have to place slashes
before quotations if you do not want the quotation to act as the end of the echo statement.
This is called escaping a character and it is discussed in our PHP Strings lesson.

With proper use of loops you can complete large tasks
with great ease.

PHP Array

PHP Array

An array is a data structure that stores one or more values in a single value. For experienced programmers it is important to note that PHP's arrays are actually maps (each key is mapped to a value).

PHP - A Numerically Indexed Array

If this is your first time seeing an array, then you may not quite
understand the concept of an array. Imagine that you own a business and
you want to store the names of all your employees in a PHP variable. How
would you go about this?
It wouldn't make much sense to have to store each name
in its own variable. Instead, it would be nice to store all the employee names inside
of a single variable. This can be done, and we show you how below.

PHP Code:

$employee_array[0] = "Bob";
$employee_array[1] = "Sally";
$employee_array[2] = "Charlie";
$employee_array[3] = "Clare";

In the above example we made use of the key / value structure of an array. The keys
were the numbers we specified in the array and the values were the names of the employees.
Each key of an array represents a value that we can manipulate and reference. The
general form for setting the key of an array equal to a value is:

• $array[key] = value;

If we wanted to reference the values that we stored into our array, the following
PHP code would get the job done.

Note: As you may have noticed from the above code example, an array's keys start from 0 and not 1. This is a very common problem for many new programmers who are used to counting from 1 and lead to "off by 1" errors. This is just something that will take experience before you are fully comfortable with it.

PHP Code:

echo "Two of my employees are "
. $employee_array[0] . " & " . $employee_array[1]; 
echo "<br />Two more employees of mine are " 
. $employee_array[2] . " & " . $employee_array[3];

Display:

Two of my employees are Bob & Sally

Two more employees of mine are Charlie & Clare

PHP arrays are quite useful when used in conjunction with
loops, which we will talk about in a later lesson. Above we showed
an example of an array that made use of integers for the keys (a numerically indexed
array). However, you can also specify a string as the key, which is referred to as an associative array.

PHP - Associative Arrays

In an associative array a key is associated with a value. If you wanted
to store the salaries of your employees in an array, a numerically indexed array would
not be the best choice. Instead, we could use the employees names as the keys in our
associative array, and the value would be their respective salary.

PHP Code:

$salaries["Bob"] = 2000;
$salaries["Sally"] = 4000;
$salaries["Charlie"] = 600;
$salaries["Clare"] = 0;

echo "Bob is being paid - $" . $salaries["Bob"] . "<br />";
echo "Sally is being paid - $" . $salaries["Sally"] . "<br />";
echo "Charlie is being paid - $" . $salaries["Charlie"] . "<br />";
echo "Clare is being paid - $" . $salaries["Clare"];

Display:

Bob is being paid - $2000

Sally is being paid - $4000

Charlie is being paid - $600

Clare is being paid - $0

Once again, the usefulness of arrays will become more apparent
once you have knowledge of for and while loops.

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 command!

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!

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:

• Always start your function with the keyword function
• Remember that your function's code must be between the "{" and the "}"
• When you are using your function, be sure you spell the function name correctly
• 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.

PHP 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: the word
case does not appear before the word default, as default is a special keyword!

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!

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:

Tizag Art Supply Order Form

Paint Brushes Erasers
Quantity:

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 associative 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.

The If Statement in PHP

The If Statement

The PHP if statement is very similar to other programming languages use of the 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, occuring 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!<br />";
}
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!<br />";
}
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 Conditional Statment

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 you work hard then you will succeed.

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.

• We first made a PHP variable called $number_three and set it equal to 3.
• 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".
• $number_three is indeed Equal To 3 and so this statement will evaluate to true.
• 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.
• 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 the if statement was false. As you can see,
the code segment contained within the else was used in this case.

PHP - Elseif

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!