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PHP Basics

PHP Basics. CSET3300. Architecture of Web Applications. Web Browser. Browser. Browser. Browser. Browser. Browser. Browser. Web Server (Apache, IIS). Middleware (PHP, Asp, ColdFusion). Relational Database. MySQL, MS-SQL, Oracle, etc. 2. PHP. What is PHP?

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PHP Basics

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  1. PHP Basics CSET3300

  2. Architecture of Web Applications Web Browser Browser Browser Browser Browser Browser Browser Web Server (Apache, IIS) Middleware (PHP, Asp, ColdFusion) Relational Database MySQL, MS-SQL, Oracle, etc. 2

  3. PHP What is PHP? PHP (Hypertext Preprocessor), Server-side script language for web development Support operating systems (Linux, many Unix variants (including HP-UX, Solaris and OpenBSD), Microsoft Windows, Mac OS X, RISC OS) History: developed in 1995 by Rasmus Lerdorf (member of the Apache Group) originally designed as a tool for tracking visitors at Lerdorf's Web site within 2 years, widely used in conjunction with the Apache server developed into full-featured, scripting language for server-side programming free, open-source 3

  4. PHP Scripts PHP is server-side PHP code is embedded in HTML using tags When a page request arrives, the server recognizes PHP content via the file extension (.php , .php3, or .phtml) The server executes the PHP code, substitutes output into the HTML The resulting page is then downloaded to the client User never sees the PHP code, only the output in the page When it comes to develop your own PHP projects, remember that you can only use PHP to send information (HTML and such) to the Web browser. You can’t do anything else within the Web browser until another request from the server has been made (a form has been submitted or a link has been clicked). PHP is cross-platform, meaning that it can be used on machines running Unix, Windows, Macintosh, and other operating systems. 4

  5. Why PHP? PHP’s advantage over basic HTML is that the latter is a limited system allowing for no flexibility or responsiveness. Visitors accessing HTML pages see simple pages with no level of customization or dynamic behavior. With PHP, you can create exciting and original pages based on whatever factors you want to consider (for example, the time of day or the user’s operating system). PHP can also interact with databases and files, handle email, and do many other things that HTML can’t. 5

  6. Writing PHP Scripts • A sample PHP code: <html> <head> <title>PHP Test Page</title> </head> <body> <?php echo “Hello, World !!!”; ?> </body> </html> • Note these important characteristics: • PHP code and HTML tags are both present • Files containing PHP code must use the php extension • The code above should named as <filename>.php and placed in a web-accessible directory on the class server. 6

  7. Testing PHP Scripts • Create “public_html” directory on et791 • Place your .php file in the directory • In a web browser type • http://et791.ni.utoledo.edu/~<utadID>/<filename.php> 7

  8. PHP Basics • PHP code must be placed within HTML code if the output is to be displayed by your browser • Note these important characteristics: • PHP code is enclosed between beginning and ending tags • PHP statements end with a semicolon character (;) • PHP statements can be broken across multiple lines, as long as tokens are not broken • Whitespace is ignored • Use the "view source" function of your browser to see what has been generated by the code. 8

  9. PHP Basics: Displaying Output • We could also use the print() statement (actually, it is a PHP language construct) to display output. • You may use either print() or echo() as they are functionally equivalent. • Note that you can use print() and echo() with or without the parentheses. Most programmers will omit the parentheses. You can also safely omit the quotation marks when only printing variable values. For example, the following are all equivalent: print ("$name"); print "$name"; print $name; 9

  10. PHP Basics: Variables • Variable identifiers are marked with a preceding dollar sign ($). • You could display "Hello, World!" using PHP variables as follows: <?php $message = "Hello, World Again!"; echo $message; ?> 10

  11. PHP Variable Identifiers • The following guidelines apply to your selection of variable identifiers: • All PHP variable identifiers (names) must begin with the dollar sign ($), following the dollar sign, the variable name must begin with a letter of the alphabet (A-Z, a-z) ) or an underscore character ( _ ) • Variable names cannot begin with a number, but after the dollar sign and initial character (letter or underscore) may contain any combination of letters, underscores and numbers • Variable names are case sensitive, so $name is NOT the same as $Name • Avoid variables with similar names • Keep variable names reasonably short and meaningful • Spaces may NOT be used in variable names • Valid PHP variable names include the following examples: $LastName $last_name $session_22 $COST $FN $page_title_num_1 11

  12. PHP Variable Declaration • PHP does not require explicit variable declaration wherein you specify the data type for the variable. • You simply use the variable as needed. All the variable data types look identical but may be handled differently. • The following code shows how to assign string, integer, and floating-point (double) values to variables: $a = "this is a string"; $b = 4; $c = 4.837; $d = "2" ; • Basically, PHP determines the variable data type based on the value you assign. 12

  13. PHP Basics: Arithmetic Operators • PHP arithmetic operators are what you would expect. Some of the basic ones are illustrated below: <?php $greeting = "Hello "; $num = 3 + 2; $num++; echo "$greeting$num people!"; ?> Output : Hello 6 people! 13

  14. PHP Basics: Strings • Just as in Perl, a string surrounded with double quotes causes variables inside it to be interpolated, but a string surrounded with single quotes does not. <?php $name = 'Susannah'; $greeting_1 = "Hello, $name!"; $greeting_2 = 'Hello, $name!'; echo "$greeting_1\n"; echo "$greeting_2\n"; ?> Output: Hello, Susannah! Hello, $name! 14

  15. PHP Basics: “\” Character • Note that the \n in the string inserts a new line into the output stream, just as in Perl or in C. • However, this only works in double-quoted strings. • Other special "escaped characters" include the tab \t and carriage return \r, dollar \$. • Here is another interesting use of the backslash character. • How would you include a backslash character in the displayed output? <?php $name = 'Susannah'; $greeting = "Hello, \"$name\"!"; echo "$greeting\n"; ?> 15

  16. PHP Basics: Comments • PHP supports C, C++ and Unix shell style comments. • For example, the following code segment illustrates all of the possibile comment delimiters: • Use the "view source" function of your browser to see what has been generated by this "commented" code. <?php echo 'This is a test'; // This is a one-line C++ style comment /* This is a multi line C style comment that continues on more than one line */ echo 'This is another test'; echo 'Still another test'; # This is a one-line shell style comment ?> 16

  17. PHP Basics: More on Comments • Note these important characteristics: • C++ style and Shell style comments can be on the same line as a PHP statement or on a line by themselves • C style comments can be a single line or multiple line • in "real" code, consistancy is better than trying to use every comment style available • Nesting C style comments can cause problems because the C style comments end with the first encountered */ delimiter. You should be careful not to nest C style comments, a common temptation when commenting large blocks. For example: <?php /* echo 'This is a test'; /* This comment will cause a problem */ */ ?> 17

  18. PHP Arrays • An array is a special data type that can store multiple values using the same variable identifier. • The commonly used term for each value in an array is an element. • Each individual array element can be accessed by the array index, which can be a number or a string. • If the array index is a string, the array is known as an associative array. • You set off array indices (regular or associative) with square brackets ([ and ]): $fruit[0] = 'banana'; $fruit[1] = 'papaya'; $favorites['animal'] = 'turtle'; $favorites['monster'] = 'cookie'; • By default, index values start at zero, and arrays are assumed to be zero-based. • In other words, if an array has five elements, the first element will be referenced as $my_array[0] and the last value will be referenced as $my_array[4]. 18

  19. PHP Arrays (ctd) • If you assign something to an array but leave the index blank, PHP assigns the object onto the end of the array. • The statements about $fruit, above, produce the same result as: $fruit[] = 'banana'; $fruit[] = 'papaya'; • You can have multidimensional arrays, too: $people['David']['shirt'] = 'blue'; $people['David']['car'] = 'minivan'; $people['Adam']['shirt'] = 'white'; $people['Adam']['car'] = 'sedan'; 19

  20. PHP Arrays (ctd) • A shortcut for creating arrays is the array() function: $fruit = array('banana','papaya'); $favorites = array('animal' => 'turtle', 'monster' => 'cookie); $people = array ('David' => array('shirt' => 'blue', 'car' => 'minivan'), 'Adam' => array('shirt' => 'white', 'car' => 'sedan')); • The built-in function count() tells you how many elements are in an array: $fruit = array('banana','papaya'); echo count($fruit); Output: 2 20

  21. PHP Built-in Functions • phpinfo(): A function that displays important information about our installation of PHP. <?php phpinfo(); ?> • Use the "view source" function of your browser to see what has been generated by this code. • With respect to its statements and functions, PHP is not case sensitive. The examples below illustrate this fact, showing equivalent forms for phpinfo(): phpInfo(); PHPinfo(); pHpInFo(); 21

  22. PHP Date & Time Functions • The basic PHP date and time functions let you format timestamps for use in database queries or simply for displaying the date and time in the browser window. • PHP includes the following date and time functions: • date(format)- Returns the current server time, formatted according to a given set of parameters. • The next slide contains valid date() formats: • time()- Returns the current server time, measured in seconds since January 1, 1970. 22

  23. PHP Date Function: Example-1 <?php echo date("Y/m/d"); echo "<br />"; echo date("Y.m.d"); echo "<br />"; echo date("Y-m-d"); ?> • Output: • 2006/07/11 • 2006.07.11 • 2006-07-11 23

  24. PHP Date Function: Example-2 • The following page uses the PHP date function to determine and display the current server time and date: • <?php • echo "<span style='font:10pt arial'>Today is”. date('lFjY').”</span>"; • echo "<br/>"; • echo "<span style='font:10pt arial'>The current time is:”. date('g:i:s a').”</span>"; • ?> • Output: • Today is Wednesday, September 5, 2007 • The current time is: 10:20:13 am 24

  25. PHP Date Function: Example-3 String concatenation is done with the dot (.) character. <?php $todaysdate = date("m") . "-" . date("d") . "-" .date("Y"); echo $todaysdate; ?> • Output: • 02-4-2010 25

  26. PHP Mail Function • The PHP mail() function is used to send emails from inside a script. • Syntax: • mail(to,subject,message,headers,parameters) Parameter Description To Required. Specifies the receiver / receivers of the email Subject Required. Specifies the subject of the email. Note: This parameter cannot contain any newline characters Message Required. Defines the message to be sent. Each line should be separated with a LF (\n). Lines should not exceed 70 characters Headers Optional. Specifies additional headers, like From, Cc, and Bcc. The additional headers should be separated with a CRLF (\r\n) Parameters Optional. Specifies an additional parameter to the sendmail program 26

  27. PHP Mail Function: Example • The simplest way to send an email with PHP is to send a text email. • In the example below we first declare the variables ($to, $subject, $message, $from, $headers), then we use the variables in the mail() function to send an e-mail: <?php $to = "someone@example.com"; $subject = "Test mail"; $message = "Hello! This is a simple email message."; $from = "someonelse@example.com"; $headers = "From: $from"; mail($to,$subject,$message,$headers); echo "Mail Sent!"; ?> 27

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