php验证码 GD库生成验证码

01

<?php

02

//调用生成验证码图片

03

//by http://www.jbxue.com[/code]

04

if

(

$_GET

[

"action"

]==

"verifycode"

)

05

{

06

rand_create();

07

}

08

//生成验证码图片

09

function

rand_create()

10

{

11

//通知浏览器将要输出PNG图片

12

Header(

"Content-type:
image/PNG"

);

13

//准备好随机数发生器种子

14

srand((double)microtime()*1000000);

15

//准备图片的相关参数

16

$im

=
imagecreate(62,20);

17

$black

=
ImageColorAllocate(

$im

,
0,0,0);

//RGB黑色标识符

18

$white

=
ImageColorAllocate(

$im

,
255,255,255);

//RGB白色标识符

19

$gray

=
ImageColorAllocate(

$im

,
200,200,200);

//RGB灰色标识符

20

//开始作图

21

imagefill(

$im

,0,0,

$gray

);

22

while

((

$randval

=rand()%100000)<10000);{

23

$_SESSION

[

"login_check_num"

]
=

$randval

;

24

//将四位整数验证码绘入图片

25

imagestring(

$im

,
5,10,3,

$randval

,

$black

);

26

}

27

//加入干扰象素

28

for

(

$i

=0;

$i

<200;

$i

++){

29

$randcolor

=
ImageColorallocate(

$im

,rand(0,255),rand(0,255),rand(0,255));

30

imagesetpixel(

$im

,
rand()%70 ,rand()%30 ,

$randcolor

);

31

}

32

//输出验证图片

33

ImagePNG(

$im

);

34

//销毁图像标识符

35

ImageDestroy(

$im

);

36

}

37

//检验验证码

38

function

rand_check()

39

{

40

if

(

$_POST

[

"reg_rand"

]
==

$_SESSION

[

"login_check_num"

]){

41

return

true;

42

}

43

else

{

44

exit

(

"验证码输入错误"

);

45

}

46

}

47

?>