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;$i < 80;$i++){
16. imagesetpixel($img, rand(0,$w), rand(0,$h), $gray);
17. }
20. $num1 = rand(1,99);
21. $num2 = rand(1,99);
23. imagestring($img, 5, 5, rand(1,10), $num1, $red);
24. imagestring($img,5,30,rand(1,10),getRand(), $white);
25. imagestring($img,5,45,rand(1,10),$num2, $green);
26. imagestring($img,5,65,rand(1,10),"=", $blue);
27. imagestring($img,5,80,rand(1,10),"?", $red);
30. header("content-type:image/png");
31. imagepng($img);
32. imagedestroy($img);
33. }
34. function getRand(){
35. $code = rand(0,1);
36. switch ($code) {
37. case 0:
38. return "+";
39. break;
40. case 1:
41. return "-";
42. break;
43. default:
44. # code...
45. break;

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