Introduction to PHP development

1. Introduction to PHP development Daniel Reeves Web Applications Developer ResNET UNC Chapel Hill

2. My Assumptions • Introductory class • Skill Level • Programming concepts • Topics Covered • Future Presentations • Mind Numbing • Materials

3. Outline • Introduction • PHP Basics • Programming and PHP • PHP Topics • Questions

4. Introduction

5. Questions for you

6. Materials • Location • http://webmasters.unc.edu/presentations/ • ZIP file of all materials (ppt, handout, code) • Handout • Terms, tips, Google search strategies • PowerPoint • Video

7. To PHP or not to PHP? The Pros • Great Documentation • Allows coding to modern standards • Open Source • Global and Diverse Developer Community • Don’t have to reinvent the wheel • Total Programmer Control • Easy to deploy

8. To PHP or not to PHP? The Cons • Inconsistent function names • Only Basic scoping • Constantly Evolving • Total Programmer Control • Not most efficient language

9. Google it !!!!! • When in doubt, search! • Search before you build • Properly formed Searches on Google • Google’s autocomplete is • For PHP searches, start by typing “php” • Suggestions will start to show

10. Programming Philosophy • Architecture Analogy • Structure: Problem/Constraints/Solution • Materials • Tools (data structures) • 4 general uses: • automation, iteration/reuse, functionality, uniformity • Know Thy Enemy • Pure problem solving

11. Programming Tips • Process Sequentially • Save often, keep multiple versions • Test incrementally • Reuse code, copy and paste • Start small and build • Solving problems is a mental process • Walk away and come back

12. PHP Basics

13. Client/Server • Client = User’s Browser • Server = Websites, Online files • PHP server only • Can only process when … • When a page is requested • After a user action has submitted the page

14. What can one do with PHP? • Database Programming • File Read/Write • Form Processing • Form Validation • Ajax Interaction • PDF Creation • File Search and Archive • Interact with web APIs • Interact with MS Office • Image Processing and • Chart Creation • XML file Read/Write • Sending Email • Writing Code

15. Topics for Today • Basic PHP/HTML interaction • Creating HTML with PHP • PHP form validation and processing • Server request interaction • Input validation • Basic debugging and error trapping • Methods for finding and correcting errors

16. What you need • Server space where PHP is enabled • http://help.unc.edu/108 • Editing program to write the code in • Notepad++ good, free editor for coding • HTML Browser for viewing created pages • Firefox is my preference • Second monitor – recommended

17. Programming PHP

18. Writing Clean Code • Writing Clean Code • Using tabs for code, white space, line breaks • Ex: which looks cleaner, easier to read? <?php echo “test”; $foo++; ?> OR <?php echo “test”; $foo++; ?>

19. PHP file, <?php tag, & ‘;’ • Files end in .php (ex: contact_form.php) • Server recognizes code within <?php tag • Requires ?> closing tag • When writing opening tag, write closing • Code not in PHP tags displays as HTML • End statements with ;

20. Example – php_tags <?php ?> testing

21. Errors and Error Messages • Empty Page • Difficult, frustrating when page is just blank • Turn on Errors • On Handout: ini_set('display_errors',1); • Shows warnings and errors • Dangerous for production code

22. Example – php_errors <?php ini_set('display_errors',1); ?> testing

23. PHP Programming – Hello World • How do I know if PHP is turned on? • php_info(); • “Hello World” • Echo statement • Single/Double quotes in PHP • echo “testing”; same as echo ‘testing’; • Use double quotes for variables

24. Example – Hello World <?php ini_set('display_errors',1); php_info(); echo “Hello World”; ?> testing

25. What are Variables ? • Basic building block of programming • Stores information/data • 3 basic parts: name, type and value • Variables store different types of data • Numbers, Strings, Boolean (True/False) • PHP Initialization • PHP Types

26. PHP Variable Syntax • All variables start with “$” • Any combination of letters, numbers, “_” • Variable Type Examples • Ex: $customer = “Daniel Reeves”; • Ex: $cost = 1.25; • Ex: $is_administrator = true; • Will use $foo as default variable • $foo, $foo1, $foo2, etc.

27. Manipulating Variables • Set Variables • $foo = 1; $foo = “test”; $foo1 = $foo • Display Variables • echo $foo; echo “$foo”; • Change and Combine text • $foo = “testing”.“ is fun”; • $foo1 = “Foo’s Value is: $foo”;

28. And Arrays? • Collections of variable values • Access various elements from index • Index number or keyword • 1st element starts at 0 • Format: $array_name[‘index’] • Array elements same as variables • Mostly for form processing • $_GET, $_POST

29. PHP Array Syntax • Create • $numbers = array(1,2,3,4,5); • $names = array(‘fn’=>”Bob”, ‘ln’=>”Smith”); • Numbers • 5 = $numbers[4]; • Strings • “Bob” = $names[‘fn’]; • “Bob” = $names[0];

30. Conditionals – If/Then/Else • Need to test truth values • If/ Else If/Else • Establish consequences based on test • Allows for options • Example: Contact form • Category for student major • When submitted, choice would be tested • Assign a different action per major

31. Conditionals – PHP Syntax • Syntax: if( testcondition ){ code } • Syntax for if, else: • if( testcondition ){ code } • else if( testcondition){ code } • else {code} • Test values with: <, <=, >, >=, !, ==, !=

32. PHP Programming – Functions • Reuse • Separate code • Elements • Name, Parameters, Code, Return • Many system functions available • include(); php_info(); echo “”; • Ex: function strlen($foo); • Returns number of characters in string

33. Review – PHP Basics • <?php and ?> tags, required “;” • Turn on errors and error messages • Variables • Strings, Numbers, Boolean (T/F) • Arrays • Conditionals • Functions

34. PHP topics – basic PHP and HTML

35. Adding Dynamic Content • Use variables • 2 Philosophies • 2 ways to display information • Echo • echo “First Name: $first_name”; • In HTML • First Name: <?= $first_name ?>

36. Example – hello_world2 <?php $first_name = “Bob”; $last_name = “Smith”; echo “<html><body>”; ?> <p> My Name is: <?= $first_name ?> <?= $last_name?> </p> </body></html>

37. Creating HTML with PHP • HTML Break and new line • To write new line to document, use \n • To add new line to rendered HTML, use <br> • Build then display • HTML put just below php on page • Nice segregation of server, client sides • Much easier to comment and debug • Create JS with PHP too

38. Display HTML uniformity • Includes • Headers, footers, menus • Widths, heights • Easily keep for element sizes uniform • Naming conventions • Prefix for names or css classes • Other repeated code • Especially if it may ever change

39. Review – PHP and HTML • Adding dynamic content • Use Variables • Output to screen: echo, <?= ?> • Breaks <br> and New Lines \n • Display Uniformity • Includes, reuse, naming, cohesive form items

40. PHP topics – PHP form processing and validation

41. PHP and form submission • Process of filling out a form • Where PHP gets access to form • GET and POST • PHP and request information • GET and POST arrays • $_GET[‘form element name’]; • $_POST[‘form element name’];

42. Getting data from your request • Good first test: use GET • Can see parameters you are sending • Don’t need form • Print entire $_GET array: print_r($_GET); • Set items from GET to variables • Use same name as name you sent • Once variable, can process further

43. Example - get <?php print_r($_GET); if($_GET){ $foo = $_GET['passed_value']; } else { $foo = "Empty"; } ?> Value is: <?= $foo ?>

44. EXAMPLE – contact_form <html><body> <form action=“contact_form.php” method=“get”> Input: <input type=“text” name=“passed_value” value=“<?= $foo ?>”> <input type=“submit” value=“Submit”> </form> </body></html>

45. Validation Options • Cleaning user input discussed later • Multiple validations of data • Client = JavaScript, Server = PHP • JS can be turned off from client, PHP cannot • Test both ends, safer, better use experience • Validation proportional to importance • Separate from security

46. Using PHP for validation • Test multiple issues for same value • Test with conditionals • Test for empty values • If($foo == “”) { do something } • Flags = Boolean variables (T/F) • Use variable to verify validation • Set to true • If any validation fails, set it to false

47. EXAMPLE – contact_form (above form) <?php if($_GET){ $foo = $_GET[‘passed_value’]; $form_passes = true; if($foo == “”){ $form_passes = false; } if(strlen($foo) < 5) {$form_passes = false; } if($form_passes){ finish processing } } ?>

48. Redisplay and Error notification • Good idea to redisplay form • Can redisplay all submitted information • Easy to find & read error messages • DIV at top of page, red and bold text • Tailored message for each issue • Interact with JS if helpful • PHP mark the fields in error

49. Process for Validation • User Submits page to server • Use PHP to get information • Test information • Not empty, length • Errors and Redisplay • Show messages • Mark errors

50. Review – PHP and Forms • PHP gets form data at submission • $_GET, $_POST and variables • Validation • Conditionals • Functions • Error notification and Redisplay • Communicate clearly with user