This document discusses various aspects of working with web forms in PHP, including: 1) Useful server variables for forms like QUERY_STRING and SERVER_NAME. 2) Accessing form parameters submitted to the server. 3) Processing forms with functions, including validating form data with techniques like checking for required fields and valid email addresses. 4) Displaying default values or error messages for form fields. 5) Stripping HTML tags from form inputs and encoding special characters for safe display. The document provides examples of implementing each of these techniques.

1. Making Web Forms
Useful Server Variables
Accessing Form Parameters
Form Processing with Functions
Validating Data
Displaying Default Values
Putting It All Together

2. Saying Hello

7. Useful Server Variables
• Aside from PHP_SELF auto global array $_SERVER
contains number of useful elements
– QUERY_STRING
– PATH_INFO
– SERVER_NAME
– DOCUMENT_ROOT
– REMOTE_ADDR
– REMOTE_HOST
– HTTP_REFERRER
– HTTP_USER_AGENT

8. Accessing Form Parameters
• A two-element form
• Printing submitted form parameters
• Multiple-valued form elements
• Accessing multiple submitted values

9. A two-element form

10. Printing submitted form parameters

13. Multiple-valued form elements

14. Accessing multiple submitted values

17. Form Processing with Functions
• Saying "Hello" with functions
• Using a hidden parameter to indicate form
submission
• Validating form data

18. Saying "Hello" with functions

22. Using a hidden parameter to indicate
form submission

26. Validating form data

31. Displaying error messages with the
form

36. Verifying a required element

37. Checking for an integer

38. Checking for a floating-point
number

39. Combining trim( ) and strlen( )

40. Changing a value in $_POST

41. Checking for a number range

42. Checking a date range

43. Checking the syntax of an email
address

44. Displaying a <select> menu

45. To validate we can use

47. A <select> menu with different choices
and values

49. Checking Submission value

50. Stripping HTML tags from a string

51. • If $_POST['comments'] contains
• I <b>love</b> sweet <div>rice</div>& tea.
• then it prints:
• I love sweet rice & tea.

52. Encoding HTML entities in a string

53. • If $_POST['comments'] contains
• I <b>love</b> sweet <div>rice</div> & tea.
• It prints
• I &lt;b&gt;love&lt;/b&gt; sweet &lt;div
&gt;rice&lt;/fancy&gt;&amp; tea.

54. • The characters that have a special meanings in
HTML (<, >, &, and ") are changed into their
entity equivalents:
– < to &lt;
– > to &gt;
– & to &amp;
– " to &quot;

55. Displaying Default Values
• Building an array of defaults
• Setting a default value in a text box
• Setting a default value in a multiline text area
• Setting a default value in a <select> menu
• Setting defaults in a multivalued <select>
menu
• Setting defaults for checkboxes and radio
buttons

56. Building an array of defaults

57. Setting a default value in a text box

58. Setting a default value in a multiline
text area

59. Setting a default value in a <select>
menu

60. Setting defaults in a multivalued
<select> menu

61. Setting defaults for checkboxes and
radio buttons

62. Putting It All Together
• Home Work