php verification code program_PHP tutorial

php verification code program A PHP verification code program function. The principle is to use the PHP gd library to generate random numbers, and then create a session and a digital picture to become a graphic verification code.

php tutorial verification code program
A PHP verification code program function. The principle is to use the PHP gd library to generate random numbers, and then create a session and a digital picture to become a graphic verification code.
*/

function fun_code($sessionname)
{
header("content-type:image/png");
session_start();
$authnum_session = '';
//$str = 'abcdefghijkmnpqrstuvwxyz1234567890';
$str = '1234567890';
$l = strlen($str);
for($i=1;$i<=4;$i++)
{
$num=rand(0,$l-1);
$authnum_session.= $str[$num];
}
$_session[$sessionname]=$authnum_session;
srand((double)microtime()*1000000);
$im = imagecreate(50,20);
$black = imagecolorallocate($im, 0,0,0);
$white = imagecolorallocate($im, 255,255,255);
$gray = imagecolorallocate($im, 200,200,200);
imagefill($im,68,30,$gray);
for($i=0;$i<3;$i++)
{
imageline($im,rand(0,30),rand(0,21),rand(20,40),rand(0,21),$li);
}
imagestring($im, 5, 8, 2, $authnum_session, $white);
for($i=0;$i<90;$i++)
{
imagesetpixel($im, rand()%70 , rand()%30 , $gray);
}
imagepng($im);
imagedestroy($im);
}
echo fun_code("code");

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