Working With PHP

1. Working With PHP David Lash Module 1 Getting Started

2. Objectives • To understand what PHP is • What is HTML • How PHP compares with CGI • Getting Started with PHP • Your first script • PHP syntax and embedding in HTML • Finding out about your PHP configuration • Using PHP variables • Numerical variables and operators • String variables, operators and a few functions • Separating PHP from HTML using <?=

3. Competencies • At end of unit be able to • Understand how PHP compares with other dynamic technologies • Create a Web Page with PHP embedded • Receive input into PHP script with variables Competency Alert: You need to know this! Common Problem Area! People seem to forget this

4. Ummm, What is HTML used for? • HTML primarily . . . • Provides instructions to browser on how file should display. • Has a set of markup language commands • Can include graphical image files • HTML documents are Static. • For example, cannot use HTML alone to: • have a document display current time • receive results of a form, query a database, and display the results • Open an input file and based on its contents, display different document content

5. Accessing HTML Files http protocol Note: The file is just retrieved no code is executed on server Note2: HTML tags interpreted on client by browser.

6. HTTP, Web Servers, Clients … • Hyper Text Transport Protocol – The protocol used to move data between Web server and Web browser. • Web Server Machine: A machine that runs web server software that listens for incoming requests on a port. • They have Internet IP addresses (e.g., 192.33.23.191) and listen on a specific ports • 193.22.12.191:80 • Web Server Software - an application, that exchanges data between Web server and Web browser. • Uses HTTP • Excepts a requests (e.g., from browser) in a specific format. • Responds to browser in a specific format. • For example, a request consist of TOP LINE, HEADER and BODY (BODY is sometimes absent). • HEADER and BODY are separated by an empty line.

7. HTML? • The Hypertext Markup Language(HTML) • used coded HTML tags • provide Web browsers display instructions. • HTML is • It is simple to use and understand • It provides ways to include things like text, graphics, sounds, links. • It is STANDARD • Its creation (and use) is one of the big reasons the WWW became popular

8. Major Server-Side Web Technologies • CGI - Computer Gateway Interface • Web Servers enable computer variety of computer languages to dynamically generate HTML • E.g. Perl, C, Unix Shell, C++ • Web Server add-on • Builds on to existing web servers – E.g., Cold Fusion • Embedded Web server • Web server has scripting language built into it. • Comprises most modern scripting technologies • ASP, JSP, PHP Competency Alert: You need to know this!

9. Often the Choice Depends on Web Server • If running a Microsoft Web Server (e.g., IIS) • More likely to use ASP or ASP.net • If running UNIX/Linux (e.g., Apache) • more likely to use PHP, or JSP. Source netscrat http://www.netscraft.com

10. What Is PHP? Advantages of Using PHP to enhance Web pages: • Easy to use. • Open source. • Multiple platform. • Started around 1996 when • Rasmus Lerdorf (a consultant) wanted to know number of people viewing his on-line resume. • Developed a CGI/Perl script that counted visitors and logged some visitor information. • He received many inquires for his CGI/Perl toolset so started giving it away for free (and called it Personal Home Page). • Got so many requests for additions, developed a next release of toolset (called PHP 2.0) • PHP 2.0 became popular and PHP moved to open source model.

11. How PHP Pages are Accessed and Interpreted

12. Compare with CGI On a UNIX server this is a fork operation Note this can be shell script, perl script, C program or whatever.

13. Objectives • To understand what PHP is • What is HTML • How PHP compares with CGI • Getting Started with PHP • Your first script • PHP syntax and embedding in HTML • Finding out about your PHP configuration • Using PHP variables • Numerical variables and operators • String variables, operators and a few functions • Separating PHP from HTML using <?=

14. Getting Started with PHP To develop and publish PHP scripts you need: • A Web server with PHP built into it • A client machine with a basic text editor and Internet connection • FTP or Telnet software Its worth noting: There are a couple good IDEs for PHP. They basically allow you create PHP scripts on PC, syntax check them, see output, and then copy to Web server

15. Common PHP Development Configurations Windows/ Apache/IIS Linux/Apache FTP or telnet Development PC Development PC PC Running Windows Apache/IIS PC Running Linux Apache

16. Creating a PHP Script File and Saving It to a Local Disk You can use a number of different editors to create your PHP script files. • The PHP script starts with a <?php tag and ends with ?>. • Between these tags is a single PHP print statement.

17. Alternative PHP Delimiters • You can alternatively start your PHP scripts with the <script> tag as follows: <script language="PHP"> print ("A simple initial script"); </script> • If haveshort_open_tagenabled in its configuration file, you can use <? and ?>. • If asp_tags is enabled in the PHP configuration file, you can use <% and %> as delimiters.

18. On a Linux/Apache Web Server Typically you: • Save files with a .php suffix (myfile.php). • Place files under public_html (e.g., /home/dlash/public_html/ Its worth noting: Some web hosts allow direct access to servers with SSH telnet. Others only allow you to use FTP to copy files over.

19. PHP Proper Syntax • Need to be syntactically correct. • For example, the print statement syntax:

20. If Use Improper Syntax • Suppose you use the wrong syntax: 1. <?php2. print ( “A simple initial script); 3. ?>

21. A Little About PHP's Syntax • Some PHP Syntax Issues: • Be careful to use quotation marks, parentheses, and brackets in pairs. • Most PHP commands end with a semicolon (;). • Be careful of case. • PHP ignores blank spaces.

22. Embedding PHP Statements Within HTML Documents 1. <html> 2. <head> 3. <title>HTML With PHP Embedded</title> </head> 4. <body> 5. <font size=5 color=”blue”>Welcome To My Page</font> 6. <?php 7. print ("<br> Using PHP is not hard<br>"); 8. ?> 9. and you can learn to use it quickly! 10. </body></html>

23. Using Backslash (\) to Generate HTML Tags with print() • Sometimes you want to output an HTML tag that also requires double quotation marks. • Use the backslash (“\”) character to signal that the double quotation marks themselves should beoutput:print ("<font color=\"blue\">"); • The above statement would output: <font color="blue"> Note! . . . You could also output the above line using the following PHP line: print (‘<font color="blue">“’); We will examine the meaning between “ and ‘ later.

24. Using Comments with PHP Scripts • Comment Syntax - Use // <?php // This is a comment ?> • Can place on Same line as a statement: <?php print ("A simple initial script"); //Output a line ?> Note: Comment lines are ignored when the script runs. They do not slow down the run-time

25. Alternative Comment Syntax PHP allows a couple of additional ways to create comments. <?php phpinfo(); # This is a built-in function ?> • Multiple line comments.<?php /* A script that gets information about the PHP version being used. */ <? phpinfo(); ?>

26. More on phpinfo() • Use a script with the following to find out about your PHP installation: • <? phpinfo(); ?> The php version This build does NOT have mysql! Location of PHP main config file Other interesting items: Apache version & configuration, php config variables, environment.

27. More on phpinfo() Allow ASP style tages Manual strongly recommends setting to off Flag values indicates which errors to display/log

28. Error Definitions . . .

29. ‘Overriding’ php.ini settings <?php ini_set('error_reporting', 2047); phpinfo(); ?> Global is ’85’ Local is 2047.

30. Apache2triad provide config administrator Show errors in browser Include HTML errors Note: Has option at bottom to save configuration. Also must restart apache for changes to take effect.

31. Setting Your own Configuration Options <?php ini_set('error_reporting', E_ALL); $x = $y + 1; print " x=$x $y=$y" ?>

32. How to read ‘Error_reporting’ variable • How did ‘get’ error_reporting = 85 ? • Answer: php.ini has the following line: error_reporting = E_COMPILE_ERROR|E_PARSE|E_ERROR|E_CORE_ERROR 1 + 4 + 16 + + 64 = 85.

33. Even more phpinfo() Enable scripts to upload to server Defines where to look for includes. (This can be set dynamically in scripts.) Send errors to logfile Require input variables to use super-global array

34. Visit www.php.net Quick function search Function manual

35. Objectives • To understand what PHP is • What is HTML • How PHP compares with CGI • Getting Started with PHP • Your first script • PHP syntax and embedding in HTML • Finding out about your PHP configuration • Using PHP variables • Numerical variables and operators • String variables, operators and a few functions • Separating PHP from HTML using <?=

36. PHP allows creating variables on the fly • For example, <?php $days = 3; $newdays = 100; $days = $newdays; ?> • A PHP variable names must: • Use a dollar sign ($) as the first character • Use a letter or an underscore character (_) as the second character.

37. Combining Variables and the print Statement • Use print statement with double quotes: $age=6; print ("Bryant is $age years old."); print (‘but george is $age years old.’); Double quotes output any variable’s value Single quotes output any variable’s name. Would output: Bryant is 6 years old but george is $age years old.

38. Using Arithmetic Operators • PHP supports various arithmetic operators. • For example <?php $apples = 12; $oranges = 14; $total_fruit = $apples + $oranges; print ("The total number of fruit is $total_fruit"); ?> These PHP statements would output The total number of fruit is 26.

39. Common PHP Numeric Operators

40. Common PHP Combined Assignment Operators

41. A Full Example 1. <html> 2. <head> <title>Variable Example </title> </head> 3. <body> 4. <?php 5. $columns = 20; 6. $rows = 12; 7. $total_seats = $rows * $columns; 8. 9. $ticket_cost = 3.75; 10. $total_revenue = $total_seats * $ticket_cost; 11. 12. $building_cost = 300; 13. $profit = $total_revenue - $building_cost; 14. 15. print ("Total Seats are $total_seats <br>"); 16. print ("Total Revenue is $total_revenue <br>"); 17. print ("Total Profit is $profit"); 18. ?> </body> </html>

42. WARNING: Using Variables with Undefined Values Use a variable without a value assigned will have no value (called a null value). PHP will NOT generate an error and will complete the expression. For example, <?php $y = 3; $y=$y + $x + 1; // $x has a null value print ("x=$x y=$y"); ?> Will output x= y=4.

43. PHP Precedence Rules • PHP follows the precedence rules listed below. • First it evaluates operators within parentheses. • Next it evaluates multiplication and division • Finally it evaluates addition and subtraction • For example, the first 2 statements evaluate to 80 while the last to 180. • $x = 100 - 10 * 2; • $y = 100 - (10 * 2); • $z = (100 - 10) * 2;

44. Objectives • To understand what PHP is • What is HTML • How PHP compares with CGI • Getting Started with PHP • Your first script • PHP syntax and embedding in HTML • Finding out about your PHP configuration • Using PHP variables • Numerical variables and operators • String variables, operators and a few functions • Separating PHP from HTML using <?=

45. Working with PHP String Variables • Use character strings for data such as customer names, addresses, product names, and descriptions. • E.g., • $name="Christopher"; • $preference="Milk Shake"; • Note: Technically it is more correct to write: • $name=‘Christopher’; • $preference=‘Milk Shake’; • Since there are no variable values to evaluate.

46. WARNING: Be Careful Not to Mix Variable Types • Be careful not to mix string and numeric variable types. <?php $x ="banana"; $sum = 1 + $x; print ("y=$sum"); ?> No error will occur instead will output: y=1

47. Using the Concatenate Operator • The concatenate operator combines two separate string variables into one. • For example, • $fullname = $firstname . $lastname; • $fullname will receive the string values of $firstname and $lastname connected together. • For example, $firstname = "John"; $lastname = "Smith"; $fullname = $firstname . $lastname; print ("Fullname=$fullname");

48. TIP: Different ways to concatenate strings. • A couple different ways to concatenate strings: • Concatenation operator • $Fullname2 = $FirstName . " " . $LastName; • Double quotes • $Fullname2 = "$FirstName $LastName"; • Concatenation combination operator • $comment = ‘I love this job’; • $comment .= ‘but the hours and not that good’; • Mix and match: • $name = ‘George’; • $comment = “$name said: I love this job”; • $comment .= ‘but the hours and not that good’;

49. The strlen() Function • Usually use one or more arguments with • Arguments are input values that functions • Often functions return a value • For example <?php $comments = "Good Job"; $len = strlen($comments); print ("Length=$len"); ?> Would output Length=8 Note: Function output would be one reason to use the concatenate operator <?php $First = 'George'; print "$First has " . strlen($First ) . ' characters'; ?> Would output: George has 6 characters

50. The trim() Function • Removes any blank characters from the beginning and end of a string. • For example, consider the following script: • <?php • $in_name = " Joe Jackson "; • $name = trim($in_name); • print ("name=$name$name"); • ?> Would output Lname=“Joe JacksonJoe Jackson”