PHP Generate verification Code (II)

1<?PHP2     //Verification Code Production3   4     Session_Start();5     //generate a Captcha picture6     Header("Content-type:image/png");7     $im= Imagecreate (44,18);//Draw a picture that specifies a wide height8     $back= Imagecolorallocate ($im, 245,245,245);//Define background color9Imagefill ($im, 0, 0,$back);//fill the background color into the picture you just drewTen     $vcodes= ""; One     Srand((Double)Microtime() *1000000); A     $srcstr= "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";  -     //generate 4-bit numbers -      for($i= 0;$i<4;$i++) { the         $font= Imagecolorallocate ($im,Rand(100,255),Rand(0,100),Rand(100,255));//Generate random Colors -         $authnum=$srcstr[Mt_rand(0,35)]; -         $vcodes.=$authnum; -Imagestring ($im, 5, 2 +$i* 10, 1,$authnum,$font); +     } -     $_session[' vcode '] =$vcodes; +  A      for($i= 0;$i<100;$i++) {//adding interfering pixels at         $randcolor= Imagecolorallocate ($im,Rand(0,255),Rand(0,255),Rand(0,255)); -Imagesetpixel ($im,Rand()%70,Rand()%30,$randcolor);//Image Point function -     } -Imagepng ($im); -Imagedestroy ($im);  -?>

PHP Generate verification Code (II)