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Application Analysis of PHP verification code on the verification page

Source: Internet
Author: User
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For a website, a page that provides verification is required. Now we need to consider the verification code application on the page. Next we will give you a detailed explanation.1. Prepare a page for displaying and submitting the PHP Verification Code 

 
 
    
  
  
  1. <?Php
    2. 
  
  
  2. 
  
  
  3. @ Header ("content-type: text/html;Charset=UTF-8 ");
    4. 
  
  
  4. 
  
  
  5. // Open the session
    6. 
  
  
  6. 
  
  
  7. Session_start ();
    8. 
  
  
  8. 
  
  
  9. ?>
    10. 
  
  
  10. 
  
  
  11. <Html>
    12. 
  
  
  12. 
  
  
  13. <Head>
    14. 
  
  
  14. 
  
  
  15. <Meta Http-equiv="Content-Type" Content="Text/html; charset = UTF-8" />
    16. 
  
  
  16. 
  
  
  17. <Title>PHP verification code example</Title>
    18. 
  
  
  18. 
  
  
  19. </Head>
    20. 
  
  
  20. 
  
  
  21. <Body>
    22. 
  
  
  22. 
  
  
  23. Verification Code:<Br/>
    24. 
  
  
  24. 
  
  
  25. <Iframe Id="Iimg" Height="100" Width=300 Src="Img. php" Frameborder="0" ></Iframe>
    26. 
  
  
  26. 
  
  
  27. <Br/>
    28. 
  
  
  28. 
  
  
  29. <Input Type=Button Value="Cannot see clearly, change one" Onclick="Iimg. location. reload ();">
    30. 
  
  
  30. 
  
  
  31. <Br>
    32. 
  
  
  32. 
  
  
  33. <Form Action="Validate. php" Method="Post">
    34. 
  
  
  34. 
  
  
  35. Enter the verification code:<Input Name="ImgId" Style="Width: 60">
    36. 
  
  
  36. 
  
  
  37. <Input Type="Submit" Value="OK">
    38. 
  
  
  38. 
  
  
  39. </Form>
    40. 
  
  
  40. 
  
  
  41. </Body>
    42. 
  
  
  42. 
  
  
  43. </Html>
    44.

2. The following is the PHP verification code generation page, which is called by on the first page. 

 
 
    
  
  
  1. <?Php
    2. 
  
  
  2. 
  
  
  3. Header ("Content-type: image/gif ");
    4. 
  
  
  4. 
  
  
  5. Session_start ();
    6. 
  
  
  6. 
  
  
  7. // The verification code is a random character. The following is an algorithm.
    8. 
  
  
  8. 
  
  
  9. $ Randval;
    10. 
  
  
  10. 
  
  
  11. For ($I=0; $ I<7; $ I ++ ){
    12. 
  
  
  12. 
  
  
  13. $Randstr=Mt_rand(Ord ('A'), ord ('Z '));
    14. 
  
  
  14. 
  
  
  15. Srand (double) microtime () * 1000000 );
    16. 
  
  
  16. 
  
  
  17. $Randv=Mt_rand(0, 10 );
    18. 
  
  
  18. 
  
  
  19. If ($ randv %2= 0 ){
    20. 
  
  
  20. 
  
  
  21. $Randval.=Mt_rand(0, 10 );
    22. 
  
  
  22. 
  
  
  23. } Else {
    24. 
  
  
  24. 
  
  
  25. $Randval.=Chr($ Randstr );
    26. 
  
  
  26. 
  
  
  27. }
    28. 
  
  
  28. 
  
  
  29. }
    30. 
  
  
  30. 
  
  
  31. // Register the PHP verification code to the session
    32. 
  
  
  32. 
  
  
  33. Session_register ($ randval );
    34. 
  
  
  34. 
  
  
  35. // The following figure shows the verification code.
    36. 
  
  
  36. 
  
  
  37. $Height=50; // Image Height
    38. 
  
  
  38. 
  
  
  39. $Width=100; // Graph width
    40. 
  
  
  40. 
  
  
  41. $Im=ImageCreateTrueColor($ Width, $ height );
    42. 
  
  
  42. 
  
  
  43. $White=ImageColorAllocate($ Instant, 255,255,255 );
    44. 
  
  
  44. 
  
  
  45. $Blue=ImageColorAllocate($ Im, 0, 0, 64 );
    46. 
  
  
  46. 
  
  
  47. ImageFill ($ im, 0, 0, $ white );
    48. 
  
  
  48. 
  
  
  49. Srand (double) microtime () * 1000000000 );
    50. 
  
  
  50. 
  
  
  51. ImageLine ($ im, mt_rand (0, $ width/3), mt_rand (0, $ height/3), mt_rand ($ width/3, $ width ), mt_rand ($ height/3, $ height), $ blue );
    52. 
  
  
  52. 
  
  
  53. Srand (double) microtime () * 1000000 );
    54. 
  
  
  54. 
  
  
  55. ImageLine ($ im, mt_rand ($ width/3, $ width), mt_rand (0, $ height/3), mt_rand (0, $ width/3), mt_rand (0, $ height/3), $ blue );
    56. 
  
  
  56. 
  
  
  57. Srand (double) microtime () * 1000000 );
    58. 
  
  
  58. 
  
  
  59. ImageString ($ im, 16, mt_rand (0, $ width-strlen ($ randval) * 10), mt_rand (0, $ height-12), $ randval, $ blue );
    60. 
  
  
  60. 
  
  
  61. ImageGIF ($ im );
    62. 
  
  
  62. 
  
  
  63. ImageDestroy ($ im );
    64. 
  
  
  64. 
  
  
  65. /*
    66. 
  
  
  66. 
  
  
  67. Note: To support the above plot functions, we must load the GD2 graph processing library in PHP to modify
    68. 
  
  
  68. 
  
  
  69. ;Extension=Php_gd2. Dll
    70. 
  
  
  70. 
  
  
  71. Is
    72. 
  
  
  72. 
  
  
  73. Extension=Php_gd2. Dll
    74. 
  
  
  74. 
  
  
  75. Enable the GD2 Library
    76. 
  
  
  76. 
  
  
  77. */
    78. 
  
  
  78. 
  
  
  79. ?>
    80.

3. This is the verification page, prompting whether the PHP Verification Code has passed verification.

 
 
    
  
  
  1. <?Php@ Header ("content-type: text/html;Charset=UTF-8 ");
    2. 
  
  
  2. 
  
  
  3. // Enable session
    4. 
  
  
  4. 
  
  
  5. Session_start ();
    6. 
  
  
  6. 
  
  
  7. // Obtain the verification code entered by the user and convert it to uppercase.
    8. 
  
  
  8. 
  
  
  9. $ImgId_req= $ _ REQUEST ['imgid'];
    10. 
  
  
  10. 
  
  
  11. $ImgId_req=Strtoupper($ ImgId_req );
    12. 
  
  
  12. 
  
  
  13. // Verify whether the session variable is registered for the string
    14. 
  
  
  14. 
  
  
  15. If (session_is_registered ($ imgId_req )){
    16. 
  
  
  16. 
  
  
  17. Echo"<Font Color=Blue >Verification passed!</Font>";
    18. 
  
  
  18. 
  
  
  19. } Else {
    20. 
  
  
  20. 
  
  
  21. Echo"<Font Color=Red >Verification error!</Font>";
    22. 
  
  
  22. 
  
  
  23. }
    24. 
  
  
  24. 
  
  
  25. // Close the session to clear all registered Variables
    26. 
  
  
  26. 
  
  
  27. Session_destroy ();
    28. 
  
  
  28. 
  
  
  29. ?>
    30.

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
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