PHP数字运算验证码

1. getValidate(100,30);
3. function getValidate($w,$h){
4. $img = imagecreate($w,$h);
6. $gray = imagecolorallocate($img,255,255,255);
7. $black = imagecolorallocate($img,rand(0,200),rand(0,200),rand(0,200));
8. $red = imagecolorallocate($img, 255, 0, 0);
9. $white = imagecolorallocate($img, 255, 255, 255);
10. $green = imagecolorallocate($img, 0, 255, 0);
11. $blue = imagecolorallocate($img, 0, 0, 255);
12. imagefilledrectangle($img, 0, 0, 100, 30, $black);
15. for($i = 0;$i imagesetpixel($img, rand(0,$w), rand(0,$h), $gray);
16. }
19. $num1 = rand(1,99);
20. $num2 = rand(1,99);
22. imagestring($img, 5, 5, rand(1,10), $num1, $red);
23. imagestring($img,5,30,rand(1,10),getRand(), $white);
24. imagestring($img,5,45,rand(1,10),$num2, $green);
25. imagestring($img,5,65,rand(1,10),"=", $blue);
26. imagestring($img,5,80,rand(1,10),"?", $red);
29. header("content-type:image/png");
30. imagepng($img);
31. imagedestroy($img);
32. }
33. function getRand(){
34. $code = rand(0,1);
35. switch ($code) {
36. case 0:
37. return "+";
38. break;
39. case 1:
40. return "-";
41. break;
42. default:
43. # code...
44. break;
45. }
46. }
48. ?>

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验证码, PHP