PHP利用GD库实现一个简单的验证码

1. $img=imagecreatetruecolor(100, 40);
2. $red=imagecolorallocate($img, 255, 0, 0);
3. $green=imagecolorallocate($img, 0, 255, 0);
4. $blue=imagecolorallocate($img, 0, 0, 255);
5. $white=imagecolorallocate($img, 255, 255, 255);
6. $black=imagecolorallocate($img, 0, 0, 0);
7. //生成图片
8. imagefill($img, 0, 0, $black);
9. //设置验证码
10. $code="";
11. for($i=0;$i$code.=rand(0,9);
12. }
13. //验证码写到图片中
14. imagestring($img, 5, 20, 15, $code, $white);
15. //加点儿干扰
16. for($i=0;$iimagesetpixel($img, rand(0,100), rand(0,40), $red);
17. imagesetpixel($img, rand(0,100), rand(0,40), $green);
18. imagesetpixel($img, rand(0,100), rand(0,40), $blue);
19. }
20. //再加点儿干扰
21. for($i=0;$iimageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $red);
22. imageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $green);
23. imageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $blue);
24. }
25. header("Content-type:image/png");
26. imagepng($img);
27. imagedestroy($img);
28. ?>

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验证码, PHP