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Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can be used repeatedly in a program. A function will not execute immediately when a page loads. A function will be executed by a call to the function. A user defined function declaration starts with the word "function": function functionName() { code to be executed;} ©1992-2012 by Pearson Education, Inc. All Rights Reserved.

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Page 1: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

Besides the built-in PHP functions, we can create our own functions.

A function is a block of statements that can be used repeatedly in a program.

A function will not execute immediately when a page loads.

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

A user defined function declaration starts with the word "function": function functionName() {

code to be executed;}

©1992-2012 by Pearson Education, Inc. All

Rights Reserved.

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A function name can start with a letter or underscore (not a number).

Function names are NOT case-sensitive.

<?phpfunction writeMsg() {

echo "Hello world!";}

writeMsg(); // call the function?>

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<?phpfunction familyName($fname) {

echo "$fname Refsnes.<br>";}

familyName("Jani");familyName("Hege");familyName("Stale");familyName("Kai Jim");familyName("Borge");?>

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Output:

Jani Refsnes.

Hege Refsnes.

Stale Refsnes.

Kai Jim Refsnes.

Borge Refsnes.

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<?phpfunction setHeight($minheight = 50) {

echo "The height is : $minheight <br>";}

setHeight(350);

setHeight(); // will use the default value of 50setHeight(135);setHeight(80);?>

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Page 5: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

sort() - sort arrays in ascending order

rsort() - sort arrays in descending order

asort() - sort associative arrays in ascending order, according to the value

ksort() - sort associative arrays in ascending order, according to the key

arsort() - sort associative arrays in descending order, according to the value

krsort() - sort associative arrays in descending order, according to the key

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Page 6: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

The following example sorts the elements of the $cars array in ascending alphabetical order:

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The following example sorts the elements of the $numbers array in ascending numerical order:

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Page 8: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

The following example sorts the elements of the $cars array in descending alphabetical order:

©1992-2012 by Pearson Education, Inc. All

Rights Reserved.

Page 9: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

The following example sorts the elements of the $numbers array in descending numerical order:

©1992-2012 by Pearson Education, Inc. All

Rights Reserved.

Page 10: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

©1992-2012 by Pearson Education, Inc. All

Rights Reserved.

Page 11: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

The following example sorts an associative array in ascending order, according to the key:

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Page 12: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

©1992-2012 by Pearson Education, Inc. All

Rights Reserved.

Page 13: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

©1992-2012 by Pearson Education, Inc. All

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addslashes()

stripslashes()

strip_tags()

htmlspecialchars()

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returns a string with backslashes in front of predefined characters (Demo).

The predefined characters are: single quote (')

double quote (")

backslash (\)

NULL

Tip: This function can be used to prepare a string for storage in a database and database queries.

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http://www.w3schools.com/php/showphp.asp?filename=demo_func_string_addslashes2
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removes backslashes added by the addslashes() function.

<!DOCTYPE html><html><body>

<?phpecho stripslashes("Who\'s Peter Griffin?");?>

</body></html>

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Output:

Who’s Peter Griffin?

http://www.w3schools.com/php/func_string_addslashes.asp
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Strips a string from HTML, XML, and PHP tags.

(Demo)

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http://www.w3schools.com/php/showphp.asp?filename=demo_func_string_strip_tags2
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The htmlspecialchars() function converts some predefined characters to HTML entities.

The predefined characters are: & (ampersand) becomes &amp;

" (double quote) becomes &quot;

' (single quote) becomes &#039;

< (less than) becomes &lt;

> (greater than) becomes &gt;

(Demo)

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http://www.w3schools.com/php/func_string_htmlspecialchars.asp
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The include statement takes all the text/code/markup that exists in the specified file and copies it into the file that uses the include statement.

Including files is very useful when you want to include the same PHP, HTML, or text on multiple pages of a website.

It is possible to insert the content of one PHP file into another PHP file (before the server executes it), with the include statement.

Syntax: include 'filename';

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Assume we have a standard footer file called "footer.php", that looks like this:

<?phpecho "<p>Copyright &copy; 1999-" . date("Y") . " W3Schools.com</p>";?>

To include the footer file in a page, use the include statement (Demo, Demo2):

<html><body><h1>Welcome to my home page!</h1><p>Some text.</p><p>Some more text.</p>

<?php include 'footer.php';?>

</body></html>

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http://www.w3schools.com/php/showphp.asp?filename=demo_include1
http://www.w3schools.com/php/showphp.asp?filename=demo_include2
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Web Server

User

User requests a particular URL

XHTML Page supplied with Form

User fills in form and submits.

Another URL is requested and the

Form data is sent to this page either in

URL or as a separate piece of data.

XHTML Response

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HTML Forms are used to select different kinds of user input.

Set the form action attribute to◦ <form action=" echo

htmlspecialchars($_SERVER["PHP_SELF"]); " method="post"> - or

◦ <form action="script.php" method="post">;

Make sure that you name each form field that you want to process as these names will be available to the processing script as variables◦ <input type="text" name="inputtext">

◦ The $_SERVER["PHP_SELF"] is a super global variable that returns the filename of the currently executing script.

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Superglobal arrays are associative arrays predefined by PHP that hold variables acquired from user input, the environment or the web server and are accessible in any variable scope.

The arrays $_GET and $_POST retrieve information sent to the server by HTTP get and post requests, respectively.

These are superglobals, which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.

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Using method = "post" appends form data to the browser request that contains the protocol and the requested resource’s URL. Scripts located on the web server’s machine can access the form data sent as part of the request.

Information sent from a form with the POST method is invisible to others (all names/values are embedded within the body of the HTTP request) and has no limits on the amount of information to send.

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Information sent from a form with the GET method is visible to everyone (all variable names and values are displayed in the URL). GET also has limits on the amount of information to send. The limitation is about 2000 characters.

GET may be used for sending non-sensitive data.

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We escape the normal meaning of a character in a string by preceding it with the backslash character (\).

Function die terminates script execution. The function’s optional argument is a string, which is printed as the script exits.

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©1992-2012 by Pearson Education, Inc. All

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Page 33: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

©1992-2012 by Pearson Education, Inc. All

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Page 34: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

©1992-2012 by Pearson Education, Inc. All

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Page 35: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

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Function mysql_connect connects to the MySQL database. It takes three arguments— the server’s hostname

a username

a password

and returns a database handle—a representation of PHP’s connection to the database, or false if the connection fails.

Function mysql_select_db selects and opens the database to be queried.

The function returns true on success or false on failure.

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Page 38: Besides the built-in PHP functions, we can create our own ... · Besides the built-in PHP functions, we can create our own functions. A function is a block of statements that can

To query the database, we call function mysql_query, specifying the query string and the database to query.

This returns a resource containing the result of the query, or false if the query fails.

It can also execute SQL statements such as INSERT or DELETEthat do not return results.

The mysql_error function returns any error strings from the database.

mysql_close closes the connection to the database specifiedin its argument.

The mysql_fetch_row function returns an array containing the values for each column in the current row of the query result ($result).

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