Unique value in array.. i.e. in nested array

I came across one limitation of array_unique: it doesn't work properly if you have arrays inside your main array.

The reason is that to compare two values, the function tests if (string) $value1 == (string) $value2. So if $value1 and $value2 are both arrays, the function will evaluate the test to 'Array' == 'Array', and decide that the $values are repeated even if the arrays are different.

So a work around is to find a better conversion of an array to a string, which can be done with json:

print "define an array with repeated scalar '1' and repeated 'array(1)':";
$a_not_unique = array(
    'a' => 1,
    'b' => 1,
    'c' => 2,
    'd' => array(1),
    'e' => array(1),
    'f' => array(2),
);
print_r($a_not_unique);

print "try to use simply array_unique, which will not work since it exludes 'array(2)':";
$a_unique_wrong = array_unique($a_not_unique);
print_r($a_unique_wrong);

print "convert to json before applying array_unique, and convert back to array, which will successfully keep 'array(2)':";
$a_unique_right = $a_not_unique;
array_walk($a_unique_right, create_function('&$value,$key', '$value = json_encode($value);'));
$a_unique_right = array_unique($a_unique_right);
array_walk($a_unique_right, create_function('&$value,$key', '$value = json_decode($value, true);'));
print_r($a_unique_right);
?>

Results:
define an array with repeated scalar '1' and repeated 'array(1)':
Array
(
    [a] => 1
    [b] => 1
    [c] => 2
    [d] => Array
        (
            [0] => 1
        )

    [e] => Array
        (
            [0] => 1
        )

    [f] => Array
        (
            [0] => 2
        )
)

try to use simply array_unique, which will not work since it exludes 'array(2)':
Array
(
    [a] => 1
    [c] => 2
    [d] => Array
        (
            [0] => 1
        )
)

convert to json before applying array_unique, and convert back to array, which will successfully keep 'array(2)':
Array
(
    [a] => 1
    [c] => 2
    [d] => Array
        (
            [0] => 1
        )

    [f] => Array
        (
            [0] => 2
        )
)

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Using cURL with PHP

The background

If you write a PHP program that is designed to go and fetch a webpage from the World Wide Web you soon find out that you are not allowed to because of a sensible restiction placed on the use of fopen(), simplexml_load_file and the like.
This restiction is absolutely vital to maintain the integrity of a shared server system and you would have to be ten bob short of a quid to allow the retrieval of all that untrusted material from the web. So an intermediate step is used.
But cURL looks complicated, especially to me, and it just looks like something else to learn. But all you need is that webpage being fetched, so you only need a bit of cURL code to do that. The good news is that it has already been written. The bad news is that it is not obvious where to stick it!

The PHP portion

(save as rsayahoo.php)

$xml = simplexml_load_file('http://rss.news.yahoo.com/rss/oddlyenough');
print "
\n"; foreach ($xml->channel->item as $item){   print "
$item->title
\n"; } print "
";
?> 

The cURL portion

But the simplexml_load_file in the function is not allowed out into the wild. So you need an intermediary step, cURL, to go and fetch the page.
So the cURL sample would be.

(save as geturl.php)

$ch = curl_init("http://rss.news.yahoo.com/rss/oddlyenough");
$fp = fopen("example_htmlpage.html", "w");

curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch);
curl_close($ch);
fclose($fp);
?> 

After the cURL portion has executed.

(upload as localrsayahoo.php)

$xml = simplexml_load_file('example_htmlpage.html');
print "
\n"; foreach ($xml->channel->item as $item){   print "
$item->title
\n"; } print "
";
?>

 

Adding the cURL and PHP portions together

Although the two programs (the cURL part and the PHP) have been shown as two seperate actions you could of course combine them into one program.

$ch = curl_init("http://rss.news.yahoo.com/rss/oddlyenough");
$fp = fopen("example_homepage.html", "w");

curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);

curl_exec($ch);
curl_close($ch);
fclose($fp);

$xml = simplexml_load_file('example_homepage.html');
print "
\n"; foreach ($xml->channel->item as $item){   print "
$item->title
\n"; } print "
";

?>

Replacement function for simplexml_load_file

This function uses the CURLOPT_RETURNTRANSFER option, so you don't have to write the results to a local file to retrieve them.

function My_simplexml_load_file($URL)
  {
  $ch = curl_init($URL);

  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_HEADER, 0);

  $xml = simplexml_load_string(curl_exec($ch));

  curl_close($ch);

  return $xml;
  }

?>

Starting , storing and destroying Session Variables in PHP

Sessions are used in PHP in various types of applications to pass data and maintain state of the user. If you are using any membership system where user has to login then after verification we have to keep the login status throughout, so we can maintain the authenticity. To do this we have to use session variables as we will store the userid inside this. Similarly for a shopping cart script we have to store the selected items of the user in session variable and display it to the visitor when required. Sessions are the unique link between the user and the server so all actions of the user can be personalized to the user and handled by the server.

We will study how to start a session, how to store variables in a session, how to destroy a session and other related functions for session handling with examples.

Here in many scripts we have used sessions and you can use them as an example. Member signup and login script uses them very often. You can download different scripts and read the code to understand how the sessions are used.

Please note that session are handled differently in PHP 5 and above so we will stick to this version only. If you are using PHP 4 then there is small difference in functions ( or syntax ) but the basic concept remains same.

Starting a session

We have verified that user entered login id and password is matching so we will give access by keeping the user id in session variable. Here is the code.

session_start();
$_SESSION['userid']=$userid;

Note that first line session_start(); this line has to be at the top of your page or this function is to be used before we send any data to the browser. The second line actually stores the data to the session variable, this can be any where within the page. The variable $userid stores the user id ( say bigstar ) now the same value is available in our session. Now let us see how to display or use this session variable.

Displaying or using a session variable

As the member has logged, its user id we can display by showing a welcome message. Here is an example.

echo “Welcome $_SESSION[userid]”;

Note that we must use the function session_start() at the starting of the page ( before sending any output to browser ) to use any session variables. We can check the existence of session with userid at every page level which are supposed to be used by logged in members.

if(!isset($_SESSION['userid'])){
echo "Sorry, Please login and use this page";
exit;
}

As you can see we have used isset function to check the presence of session variable storing userid. If the variable does not exist then we are displaying a message asking the user to login and then terminating the script by using exit command. This part of the script you can see in detail at our login and logout script.

Displaying all the session variable.

We can store different data in session variables. In our example we have used only one ( that is $_SESSION[userid] ) but we can store other data also. Let us add name to the session variable like this.

$_SESSION['name']="Ronny";

Now we can display all the elements of the session array and see what are the session variables created and what data they store.

while (list ($key, $val) = each ($_SESSION)) {
echo "$key -> $val
";
}

you will get a list like this.

userid -> plus2net
name -> Ronny

Destroying the session

To destroy or delete the sessions we can use these two commands. It is advisable to use these commands in this sequence to destroy remove sessions in PHP.

session_unset();
session_destroy();

Important : Don't forget to give session_start() command at the staring of the page.
You can test all the above code to learn and understand how the session works by running these sample codes at your system. Open the index.php file and rest you can easily understand.

APC caching for Web services - Yahoo

error_reporting(E_ALL);

$request =  'http://search.yahooapis.com/ImageSearchService/V1/imageSearch?appid=YahooDemo&query=Madonna&results=1';

// Number of seconds until the cache gets stale
$cache_timeout = 7200;

// Check the cache
$response = request_cache($request, $cache_timeout);

if ($response === false) {
 die('Request failed');
}

// Output the XML
echo htmlspecialchars($response, ENT_QUOTES);

// This is the main caching routine. More robust error checking should
// be implemented.

function request_cache($url, $ttl) {
 if(!$xml = apc_fetch($url)) {
  $xml = file_get_contents($url);
  if ($xml === false) return false;
  apc_store($url,$xml, $ttl);
 }
 return $xml;
}

?>

PHPfundamentals Series: A Background on Statics (Part 1 on Statics)

Just beyond reading the title, you’ve more than likely come to this article as the curious yet uninformed, the mad and raving lunatic, or as an enlightened one. Static class members (from here on called simply, “statics”) in PHP conjure both the best and worst in developers for a variety of reasons. In part 1 of this series of articles on statics, we’ll explore some background to get a better understanding of statics in PHP.

Some Static Background And Understanding

Before we can move into the arguments that surround statics, we first need to understand what they are in the context of PHP.  The core of the PHP language and runtime can draw some pretty big corollaries from the Java/JVM and C#/.NET language platforms. The biggest, and most important for the purposes of this article, is PHP’s object model. Like Java and .NET, PHP follows a class-based, single-inheritance, multiple-interface model- a tenet described by the grandfather of OO languages: smalltalk. Of course, PHP applies its own “perspective” when it comes to the actual implementation details in that of typing, casting, mixed-paradigm usage, and so on; but the foundation for the object model is clearly defined.
That said, it is easy for the PHP community to draw comparisons and, more importantly, “borrow” best practices from both the Java and .NET communities. We certainly have borrowed our fair share with regards to development time tools, infrastructure tools and design patterns. Over the past 5 to 7 years, there has been an increasing adoption of best practices and patterns from the enterprise Java community, particularly in the form of two major texts: GoF and PoEAA. The GoF (Gang of Four) text primarily discusses best practices in the form of code structure and reuse: factory, singleton, adapter, composite, facade, iterator and observer to name a few. PoEAA (Patterns of Enterprise Application Architecture), on the other hand, attempts to solve higher order problems, particularly architectural problems at the application layer: MVC, Page Controller, Front Controller, Domain Model, Table and Row Gateway, and so on. While the examples are primarily executed in Java, they are structurally similar when implemented in PHP, so much so that PHP developers can read the Java examples as pseudo-code. This is what makes these patterns so applicable and thus popular in the PHP community.
Since we now know where these usage patterns originated, we should have a look at the target language platform: PHP. The key concept which delineates the PHP platform from the JVM and .NET platforms, is that PHP by default assumes a shared-nothing architecture. What does this mean? It means out of the box, PHP is not a persistent application platform. PHP’s runtime is built around the notion of primarily solving the web problem. In turn, since the web is request driven, you might say that an application written in PHP is also request driven. Put another way, the scope of your application is bound to a single request. The shared-nothing aspect means that the state of the application is built-up and torn-down upon the start and completion of each request to your application. Conversely, Java and .NET offer a persistent application stack which means the application’s state exists separate from the requests that come in via the web server. So, in PHP, the many requests each contain a single running instance of your application. In Java/.NET, the single application running handles the many requests.

Statics in Analogies

Still don’t get it? Let’s talk in a couple of analogies. Let’s assume we’ve built a basic application with the “out-of-the-box” technologies offered; one built on top of PHP and the other built on top of Java (or .NET, you can choose.) With your Java/.NET application, if a request is never received from your web server, the application is indeed still running. In PHP, if a request is never received from your web server, the application has NEVER run. The runtime of a Java/.NET application might be hours or days, whereas the runtime of a PHP application is a long as it takes to service the request. This analogy’s mileage may vary, and it is surely intended for demonstrative purposes. You could inject any number of monkey wrenches into it, but for all intents and purposes- it’s correct and it works.
Understanding the full scope of an applications runtime state is the most important aspect into understanding the role of static class members in OO programming. Static class members live as long as the application runtime is valid and alive. What this means it is that any class member state that has been set during any operation during the applications runtime will persist until the application ceases to exist. Looking back at our main platform differences, we can see that in the Java/.NET platform, statics members created in the scope of an application layer will be around until someone pushes the “shutdown” button on that application. This could mean a static member or static state is persisted for hours, days, or even longer. Like these persistent application stacks, PHP will destroy any static members and state at the end of the applications lifecycle. Unlike these persistent application stacks, the application lifecycle ends with the completion of a web request. This means that static members and static state in PHP, for the average web application, sticks around for seconds or less and is only valid in the context of a single web request.

Statics in Pictures

Still don’t get it? Lets have a look at a few images to better explain these concepts.
The following images will attempt to explain the various layers of a web application, one from the perspective of the JVM/.NET platform, the other from the perspective of the PHP platform. (For all intents and purposes, the PHP platform could also be any scripting language executed by an apache module or fastcgi.)
The green layer is the web server layer, this is the process that will attach to port 80 and listen for requests. The blue layer represents the application process itself. This layer is responsible for global application state and class-based static state. The orange layer is a request which comes in from the web, this is typically what we’ve called a page request. Inside of each web request is the yellow layer, which represents the page-lifecycle. In terms of the application, this is where all of the request specific application routines happen including page startup and business logic.

Contrasted against …

The most important thing to take away from these images, particularly with respect to understanding statics, is the blue layer, or the layer that best represents the scope of globals and static members. This is the heart of what is meant by a “shared-nothing” architecture. It is this key difference that affects how we architect the code for our web applications.
In the next article in this series, we’ll have a look at PHP’s application architecture in greater detail and how it solves problems that might arise from a shared-nothing style architecture, why this architecture is arguably better for the web and cloud based services, but most importantly, how statics fit into this paradigm.

PHP Cookies

A cookie is often used to identify a user.

---

What is a Cookie?

A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.

---

How to Create a Cookie?

The setcookie() function is used to set a cookie.
Note: The setcookie() function must appear BEFORE the tag.

Syntax

setcookie(name, value, expire, path, domain);

Example 1

In the example below, we will create a cookie named "user" and assign the value "Alex Porter" to it. We also specify that the cookie should expire after one hour:

setcookie("user", "Alex Porter", time()+3600);    ?> .....

Note: The value of the cookie is automatically URLencoded when sending the cookie, and automatically decoded when received (to prevent URLencoding, use setrawcookie() instead).

Example 2

You can also set the expiration time of the cookie in another way. It may be easier than using seconds.

$expire=time()+60*60*24*30; setcookie("user", "Alex Porter", $expire); ?> .....

In the example above the expiration time is set to a month (60 sec * 60 min * 24 hours * 30 days).

---

How to Retrieve a Cookie Value?

The PHP $_COOKIE variable is used to retrieve a cookie value.

In the example below, we retrieve the value of the cookie named "user" and display it on a page:

// Print a cookie echo $_COOKIE["user"]; // A way to view all cookies print_r($_COOKIE); ?>

In the following example we use the isset() function to find out if a cookie has been set:

if (isset($_COOKIE["user"]))   echo "Welcome " . $_COOKIE["user"] . "! "; else   echo "Welcome guest! "; ?>

---

How to Delete a Cookie?

When deleting a cookie you should assure that the expiration date is in the past.
Delete example:

// set the expiration date to one hour ago setcookie("user", "", time()-3600); ?>

---

What if a Browser Does NOT Support Cookies?

If your application deals with browsers that do not support cookies, you will have to use other methods to pass information from one page to another in your application. One method is to pass the data through forms (forms and user input are described earlier in this tutorial).
The form below passes the user input to "welcome.php" when the user clicks on the "Submit" button:
Retrieve the values in the "welcome.php" file like this:

Name:
Age:

Welcome .

You are years old.

PHP File Handling

The fopen() function is used to open files in PHP.

---

Opening a File

The fopen() function is used to open files in PHP.
The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:

$file=fopen("welcome.txt","r"); ?>

The file may be opened in one of the following modes:

Modes	Description
r	Read only. Starts at the beginning of the file
r+	Read/Write. Starts at the beginning of the file
w	Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+	Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
a	Append. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+	Read/Append. Preserves file content by writing to the end of the file
x	Write only. Creates a new file. Returns FALSE and an error if file already exists
x+	Read/Write. Creates a new file. Returns FALSE and an error if file already exists

Note: If the fopen() function is unable to open the specified file, it returns 0 (false).

Example

The following example generates a message if the fopen() function is unable to open the specified file:

$file=fopen("welcome.txt","r") or exit("Unable to open file!"); ?>

---

Closing a File

The fclose() function is used to close an open file:

$file = fopen("test.txt","r"); //some code to be executed fclose($file); ?>

---

Check End-of-file

The feof() function checks if the "end-of-file" (EOF) has been reached.

The feof() function is useful for looping through data of unknown length.
Note: You cannot read from files opened in w, a, and x mode!

if (feof($file)) echo "End of file";

---

Reading a File Line by Line

The fgets() function is used to read a single line from a file.
Note: After a call to this function the file pointer has moved to the next line.

Example

The example below reads a file line by line, until the end of file is reached:

$file = fopen("welcome.txt", "r") or exit("Unable to open file!"); //Output a line of the file until the end is reached while(!feof($file))   {   echo fgets($file). " ";   } fclose($file); ?>

---

Reading a File Character by Character

The fgetc() function is used to read a single character from a file.
Note: After a call to this function the file pointer moves to the next character.

Example

The example below reads a file character by character, until the end of file is reached:
$file=fopen("welcome.txt","r") or exit("Unable to open file!");
while (!feof($file))
  {
  echo fgetc($file);
  }
fclose($file);
?>

PHP Include File

Server Side Includes (SSI)

You can insert the content of one PHP file into another PHP file before the server executes it, with the include() or require() function.
The two functions are identical in every way, except how they handle errors:

• include() generates a warning, but the script will continue execution
• require() generates a fatal error, and the script will stop

These two functions are used to create functions, headers, footers, or elements that will be reused on multiple pages.
Server side includes saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. When the header needs to be updated, you can only update the include file, or when you add a new page to your site, you can simply change the menu file (instead of updating the links on all your web pages).

---

PHP include() Function

The include() function takes all the content in a specified file and includes it in the current file.
If an error occurs, the include() function generates a warning, but the script will continue execution.

Example 1

Assume that you have a standard header file, called "header.php". To include the header file in a page, use the include() function:

Welcome to my home page! Some text.

Example 2

Assume we have a standard menu file, called "menu.php", that should be used on all pages:

Home Tutorials References Examples About Us Contact Us

All pages in the Web site should include this menu file. Here is how it can be done:

Welcome to my home page. Some text.

If you look at the source code of the page above (in a browser), it will look like this:

Home Tutorials References Examples About Us Contact Us Welcome to my home page! Some text.

---

PHP require() Function

The require() function is identical to include(), except that it handles errors differently.
If an error occurs, the include() function generates a warning, but the script will continue execution. The require() generates a fatal error, and the script will stop.

Error Example include() Function

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

Error message:

Warning: include(wrongFile.php) [function.include]: failed to open stream: No such file or directory in C:\home\website\test.php on line 5 Warning: include() [function.include]: Failed opening 'wrongFile.php' for inclusion (include_path='.;C:\php5\pear') in C:\home\website\test.php on line 5 Hello World!

Notice that the echo statement is executed! This is because a Warning does not stop the script execution.

Error Example require() Function

Now, let's run the same example with the require() function.

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

Error message:
Warning: require(wrongFile.php) [function.require]:
failed to open stream:
No such file or directory in C:\home\website\test.php on line 5

Fatal error: require() [function.require]:
Failed opening required 'wrongFile.php'
(include_path='.;C:\php5\pear')
in C:\home\website\test.php on line 5

PHP Date() Function

The PHP date() function is used to format a time and/or date.

---

The PHP Date() Function

The PHP date() function formats a timestamp to a more readable date and time.
A timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred.

Syntax

date(format,timestamp)

Parameter	Description
format	Required. Specifies the format of the timestamp
timestamp	Optional. Specifies a timestamp. Default is the current date and time

---

PHP Date() - Format the Date

The required format parameter in the date() function specifies how to format the date/time.
Here are some characters that can be used:

• d - Represents the day of the month (01 to 31)
• m - Represents a month (01 to 12)
• Y - Represents a year (in four digits)

A list of all the characters that can be used in the format parameter, can be found in our PHP Date reference.
Other characters, like"/", ".", or "-" can also be inserted between the letters to add additional formatting:

echo date("Y/m/d") . " "; echo date("Y.m.d") . " "; echo date("Y-m-d") ?>

The output of the code above could be something like this:

2009/05/11 2009.05.11 2009-05-11

---

PHP Date() - Adding a Timestamp

The optional timestamp parameter in the date() function specifies a timestamp. If you do not specify a timestamp, the current date and time will be used.
The mktime() function returns the Unix timestamp for a date.
The Unix timestamp contains the number of seconds between the Unix Epoch (January 1 1970 00:00:00 GMT) and the time specified.

Syntax for mktime()

mktime(hour,minute,second,month,day,year,is_dst)

To go one day in the future we simply add one to the day argument of mktime():

$tomorrow = mktime(0,0,0,date("m"),date("d")+1,date("Y")); echo "Tomorrow is ".date("Y/m/d", $tomorrow); ?>

The output of the code above could be something like this:
Tomorrow is 2009/05/12

PHP $_POST Function

The built-in $_POST function is used to collect values in a form with method="post".

---

The $_POST Function

The built-in $_POST function is used to collect values from a form sent with method="post".
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Note: However, there is an 8 Mb max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).

---

When to use method="post"?

Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
However, because the variables are not displayed in the URL, it is not possible to bookmark the page.

---

The PHP $_REQUEST Function

The PHP built-in $_REQUEST function contains the contents of both $_GET, $_POST, and $_COOKIE.
The $_REQUEST function can be used to collect form data sent with both the GET and POST methods.

Example

Welcome !

You are years old.

PHP $_GET Function

The built-in $_GET function is used to collect values in a form with method="get".

---

The $_GET Function

The built-in $_GET function is used to collect values from a form sent with method="get".
Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send (max. 100 characters).

PHP Forms and User Input

The PHP $_GET and $_POST variables are used to retrieve information from forms, like user input.

---

PHP Form Handling

The most important thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.

Example

The example below contains an HTML form with two input fields and a submit button:

Name: Age:

When a user fills out the form above and click on the submit button, the form data is sent to a PHP file, called "welcome.php":
"welcome.php" looks like this:

Welcome ! You are years old.

Output could be something like this:
Welcome John!
You are 28 years old.

PHP Functions

The real power of PHP comes from its functions.

In PHP, there are more than 700 built-in functions.

---

PHP Built-in Functions

For a complete reference and examples of the built-in functions, please visit our PHP Reference.

---

PHP Functions

In this chapter we will show you how to create your own functions.
To keep the script from being executed when the page loads, you can put it into a function.
A function will be executed by a call to the function.
You may call a function from anywhere within a page.

---

Create a PHP Function

A function will be executed by a call to the function.

Syntax

function functionName() { code to be executed; }

PHP function guidelines:

• Give the function a name that reflects what the function does
• The function name can start with a letter or underscore (not a number)

Example

A simple function that writes my name when it is called:

function writeName() { echo "Kai Jim Refsnes"; } echo "My name is "; writeName(); ?>

Output:

My name is Kai Jim Refsnes

---

PHP Functions - Adding parameters

To add more functionality to a function, we can add parameters. A parameter is just like a variable.
Parameters are specified after the function name, inside the parentheses.

Example 1

The following example will write different first names, but equal last name:

function writeName($fname) { echo $fname . " Refsnes. "; } echo "My name is "; writeName("Kai Jim"); echo "My sister's name is "; writeName("Hege"); echo "My brother's name is "; writeName("Stale"); ?>

Output:

My name is Kai Jim Refsnes. My sister's name is Hege Refsnes. My brother's name is Stale Refsnes.

Example 2

The following function has two parameters:

function writeName($fname,$punctuation) { echo $fname . " Refsnes" . $punctuation . " "; } echo "My name is "; writeName("Kai Jim","."); echo "My sister's name is "; writeName("Hege","!"); echo "My brother's name is "; writeName("Ståle","?"); ?>

Output:

My name is Kai Jim Refsnes. My sister's name is Hege Refsnes! My brother's name is Ståle Refsnes?

 

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PHP Functions - Return values

To let a function return a value, use the return statement.

Example

function add($x,$y)
{
$total=$x+$y;
return $total;
}

echo "1 + 16 = " . add(1,16);
?>

PHP Looping - For Loops

Loops execute a block of code a specified number of times, or while a specified condition is true.

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The for Loop

The for loop is used when you know in advance how many times the script should run.

Syntax

for (init; condition; increment)   {   code to be executed;   }

Parameters:

• init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop)
• condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends.
• increment: Mostly used to increment a counter (but can be any code to be executed at the end of the loop)

Note: Each of the parameters above can be empty, or have multiple expressions (separated by commas).

Example

The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:

for ($i=1; $i<=5; $i++)   {   echo "The number is " . $i . " ";   } ?>

Output:

The number is 1 The number is 2 The number is 3 The number is 4 The number is 5

---

The foreach Loop

The foreach loop is used to loop through arrays.

Syntax

foreach ($array as $value)   {   code to be executed;   }

For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.

Example

The following example demonstrates a loop that will print the values of the given array:

$x=array("one","two","three"); foreach ($x as $value)   {   echo $value . " ";   } ?>

Output:
one
two
three

PHP Looping - While Loops

Loops execute a block of code a specified number of times, or while a specified condition is true.

---

PHP Loops

Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In PHP, we have the following looping statements:

• while - loops through a block of code while a specified condition is true
• do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true
• for - loops through a block of code a specified number of times
• foreach - loops through a block of code for each element in an array

---

The while Loop

The while loop executes a block of code while a condition is true.

Syntax

while (condition)   {   code to be executed;   }

Example

The example below defines a loop that starts with i=1. The loop will continue to run as long as i is less than, or equal to 5. i will increase by 1 each time the loop runs:

$i=1; while($i<=5)   {   echo "The number is " . $i . " ";   $i++;   } ?>

Output:

The number is 1 The number is 2 The number is 3 The number is 4 The number is 5

---

The do...while Statement

The do...while statement will always execute the block of code once, it will then check the condition, and repeat the loop while the condition is true.

Syntax

do   {   code to be executed;   } while (condition);

Example

The example below defines a loop that starts with i=1. It will then increment i with 1, and write some output. Then the condition is checked, and the loop will continue to run as long as i is less than, or equal to 5:

$i=1; do   {   $i++;   echo "The number is " . $i . " ";   } while ($i<=5); ?>

Output:
The number is 2
The number is 3
The number is 4
The number is 5
The number is 6

PHP Arrays

What is an Array?

A variable is a storage area holding a number or text. The problem is, a variable will hold only one value.
An array is a special variable, which can store multiple values in one single variable.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

$cars1="Saab"; $cars2="Volvo"; $cars3="BMW";

However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The best solution here is to use an array!
An array can hold all your variable values under a single name. And you can access the values by referring to the array name.
Each element in the array has its own index so that it can be easily accessed.
In PHP, there are three kind of arrays:

• Numeric array - An array with a numeric index
• Associative array - An array where each ID key is associated with a value
• Multidimensional array - An array containing one or more arrays

---

Numeric Arrays

A numeric array stores each array element with a numeric index.
There are two methods to create a numeric array.
1. In the following example the index are automatically assigned (the index starts at 0):

$cars=array("Saab","Volvo","BMW","Toyota");

2. In the following example we assign the index manually:

$cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota";

Example

In the following example you access the variable values by referring to the array name and index:

$cars[0]="Saab"; $cars[1]="Volvo"; $cars[2]="BMW"; $cars[3]="Toyota"; echo $cars[0] . " and " . $cars[1] . " are Swedish cars."; ?>

The code above will output:

Saab and Volvo are Swedish cars.

---

Associative Arrays

An associative array, each ID key is associated with a value.
When storing data about specific named values, a numerical array is not always the best way to do it.
With associative arrays we can use the values as keys and assign values to them.

Example 1

In this example we use an array to assign ages to the different persons:

$ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);

Example 2

This example is the same as example 1, but shows a different way of creating the array:

$ages['Peter'] = "32"; $ages['Quagmire'] = "30"; $ages['Joe'] = "34";

The ID keys can be used in a script:

$ages['Peter'] = "32"; $ages['Quagmire'] = "30"; $ages['Joe'] = "34"; echo "Peter is " . $ages['Peter'] . " years old."; ?>

The code above will output:

Peter is 32 years old.

---

Multidimensional Arrays

In a multidimensional array, each element in the main array can also be an array. And each element in the sub-array can be an array, and so on.

Example

In this example we create a multidimensional array, with automatically assigned ID keys:

$families = array   (   "Griffin"=>array   (   "Peter",   "Lois",   "Megan"   ),   "Quagmire"=>array   (   "Glenn"   ),   "Brown"=>array   (   "Cleveland",   "Loretta",   "Junior"   )   );

The array above would look like this if written to the output:

Array ( [Griffin] => Array   (   [0] => Peter   [1] => Lois   [2] => Megan   ) [Quagmire] => Array   (   [0] => Glenn   ) [Brown] => Array   (   [0] => Cleveland   [1] => Loretta   [2] => Junior   ) )

Example 2

Lets try displaying a single value from the array above:

echo "Is " . $families['Griffin'][2] . " a part of the Griffin family?";

The code above will output:
Is Megan a part of the Griffin family?

PHP Switch Statement

Conditional statements are used to perform different actions based on different conditions.

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The PHP Switch Statement

Use the switch statement to select one of many blocks of code to be executed.

Syntax

switch (n) { case label1:   code to be executed if n=label1;   break; case label2:   code to be executed if n=label2;   break; default:   code to be executed if n is different from both label1 and label2; }

This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if no match is found.

Example

switch ($x)
{
case 1:
  echo "Number 1";
  break;
case 2:
  echo "Number 2";
  break;
case 3:
  echo "Number 3";
  break;
default:
  echo "No number between 1 and 3";
}
?>

PHP If...Else Statements

Conditional statements are used to perform different actions based on different conditions.

---

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.
You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:

• if statement - use this statement to execute some code only if a specified condition is true
• if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false
• if...elseif....else statement - use this statement to select one of several blocks of code to be executed
• switch statement - use this statement to select one of many blocks of code to be executed

---

The if Statement

Use the if statement to execute some code only if a specified condition is true.

Syntax

if (condition) code to be executed if condition is true;

The following example will output "Have a nice weekend!" if the current day is Friday:

$d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; ?>

Notice that there is no ..else.. in this syntax. The code is executed only if the specified condition is true.

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The if...else Statement

Use the if....else statement to execute some code if a condition is true and another code if a condition is false.

Syntax

if (condition)   code to be executed if condition is true; else   code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":

$d=date("D"); if ($d=="Fri")   echo "Have a nice weekend!"; else   echo "Have a nice day!"; ?>

If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:

$d=date("D"); if ($d=="Fri")   {   echo "Hello! ";   echo "Have a nice weekend!";   echo "See you on Monday!";   } ?>

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The if...elseif....else Statement

Use the if....elseif...else statement to select one of several blocks of code to be executed.

Syntax

if (condition)   code to be executed if condition is true; elseif (condition)   code to be executed if condition is true; else   code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":



$d=date("D");
if ($d=="Fri")
  echo "Have a nice weekend!";
elseif ($d=="Sun")
  echo "Have a nice Sunday!";
else
  echo "Have a nice day!";
?>

PHP Operators

Operators are used to operate on values.

PHP Operators
This section lists the different operators used in PHP.
Arithmetic Operators

Operator	Description	Example	Result
+	Addition	x=2 x+2	4
-	Subtraction	x=2 5-x	3
*	Multiplication	x=4 x*5	20
/	Division	15/5 5/2	3 2.5
%	Modulus (division remainder)	5%2 10%8 10%2	1 2 0
++	Increment	x=5 x++	x=6
--	Decrement	x=5 x--	x=4

Assignment Operators

Operator	Example	Is The Same As
=	x=y	x=y
+=	x+=y	x=x+y
-=	x-=y	x=x-y
*=	x*=y	x=x*y
/=	x/=y	x=x/y
.=	x.=y	x=x.y
%=	x%=y	x=x%y

Comparison Operators

Operator	Description	Example
==	is equal to	5==8 returns false
!=	is not equal	5!=8 returns true
<>	is not equal	5<>8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

Logical Operators

Operator	Description	Example
&&	and	x=6 y=3 (x < 10 && y > 1) returns true
||	or	x=6 y=3 (x==5 || y==5) returns false
!	not	x=6 y=3 !(x==y) returns true

PHP String Variables

A string variable is used to store and manipulate text.

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String Variables in PHP

String variables are used for values that contains characters.
In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.
After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.
Below, the PHP script assigns the text "Hello World" to a string variable called $txt:
 --------------------------------

$txt="Hello World"; echo $txt; ?>

---------------------------------
The output of the code above will be:

Hello World

Now, lets try to use some different functions and operators to manipulate the string.

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The Concatenation Operator

There is only one string operator in PHP.
The concatenation operator (.)  is used to put two string values together.
To concatenate two string variables together, use the concatenation operator:
--------------------------------

$txt1="Hello World!"; $txt2="What a nice day!"; echo $txt1 . " " . $txt2; ?>

--------------------------------
The output of the code above will be:

Hello World! What a nice day!

If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string (a space character), to separate the two strings.

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The strlen() function

The strlen() function is used to return the length of a string.
Let's find the length of a string:
--------------------------------

echo strlen("Hello world!"); ?>

--------------------------------
The output of the code above will be:

12

The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string).

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The strpos() function

The strpos() function is used to search for character within a string.
If a match is found, this function will return the position of the first match. If no match is found, it will return FALSE.
Let's see if we can find the string "world" in our string:
--------------------------------

echo strpos("Hello world!","world"); ?>

--------------------------------
The output of the code above will be:

6

The position of the string "world" in our string is position 6. The reason that it is 6 (and not 7), is that the first position in the string is 0, and not 1.