php生成验证码代码

<?phpsession_start();//开启session$strCode = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,y,z";$strCode .= "A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";$strList = explode(",", $strCode);//分割字符串$StrMax = count($strList)-1;//获得字符的总个数$verifyCode = "";//随机取出四个字符for($i=0;$i<4;$i++){$strRnad = rand(0,$StrMax);$verifyCode .= $strList[$strRnad]; }$_SESSION['verifyCode'] = $verifyCode;//将字符串存入session中$im = imagecreatetruecolor(100, 30);//创建画布//加干扰直线和曲线for($k=1;$k<=10;$k++){imageline($im, rand(0,100), rand(0,30), rand(0,90), rand(0,30), imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255)));imagearc($im, rand(0,100), rand(0,30), rand(0,50), rand(0,15), rand(0,180), rand(0,90), imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255)));}//加干扰点for($j=1;$j<=100;$j++){imagesetpixel($im, rand(2,98), rand(2,28), imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255)));}//把上面取到的字符写入画布中imagestring($im, rand(1,5), rand(0,75), rand(0,15), $verifyCode, imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255)));header("content-type: image/png");imagepng($im);//输出图片imagedestroy($im);//销毁图片?>