php写的一个验证码

2. session_start();
3. $image = imagecreatetruecolor(58,22);
4. $color_Background = imagecolorallocate($image,255,255,255);
5. imagefill($image,0,0,$color_Background);
6. $key = array(
7. ‘0′,’1′,’2′,’3′,’4′,’5′,’6′,’7′,’8′,’9′,
8. ‘a’,'b’,'c’,'d’,'e’,'f’,'g’,'h’,'i’,'j’,'k’,'l’,'m’,'n’,'o’,'p’,'q’,'r’,’s’,'t’,'u’,'v’,'w’,'x’,'y’,'z’,
9. ‘A’,'B’,'C’,'D’,'E’,'F’,'G’,'H’,'I’,'J’,'K’,'L’,'M’,'N’,'O’,'P’,'Q’,'R’,'S’,'T’,'U’,'V’,'W’,'X’,'Y’,'Z’);
10. $string = null;
11. $char_X = 6;
12. $char_Y = 0;
13. for($i=0;$i{
14. $char_Y = mt_rand(0,5);
15. $char = $key[mt_rand(0,61)];
16. $string .= $char;
17. $color_Char = imagecolorallocate($image,mt_rand(0,230),mt_rand(0,230),mt_rand(0,230));
18. imagechar($image,5,$char_X,$char_Y,$char,$color_Char);
19. $char_X = $char_X + mt_rand(8,15);
20. }
21. $line_X1 = 0;
22. $line_Y1 = 0;
23. $line_X2 = 0;
24. $line_Y2 = 0;
25. for($i=0;$i
26. {
27. $line_X1 = mt_rand(0,58);
28. $line_Y1 = mt_rand(0,22);
29. $line_X2 = mt_rand(0,58);
30. $line_Y2 = mt_rand(0,22);
31. $line_X1 = $line_X1;
32. $line_Y1 = $line_Y1;
33. $line_X2 = $line_X1 + mt_rand(1,8);
34. $line_Y2 = $line_Y1 + mt_rand(1,8);
35. $color_Line = imagecolorallocate($image,mt_rand(0,230),mt_rand(0,230),mt_rand(0,230));
36. imageline($image,$line_X1,$line_Y1,$line_X2,$line_Y2,$color_Line);
37. }
38. $_SESSION['seccode'] = $string;
39. @header(“Expires: -1″);
40. @header(“Cache-Control: no-store, private, post-check=0, pre-check=0, max-age=0″, FALSE);
41. @header(“Pragma: no-cache”);
42. header(‘Content-Type: image/jpeg’);
43. imagepng($image);
44. imagedestroy($image);
45. ?>

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