PHP Generation Verification Code detailed tutorial _php tutorial

This article provides a PHP tutorial to generate a detailed tutorial of verification code, the first is about the build validation core code, followed by a build and Invoke method.

Header ("Content-type:image/png");
$num = ' 1234 ';
$imagewidth = 60;
$imageheight = 18;

$numimage = Imagecreate ($imagewidth, $imageheight);
Imagecolorallocate ($numimage, 240,240,240);
for ($i =0; $i
$x = Mt_rand (1,8) + $imagewidth * $i/4;
$y = Mt_rand (1, $imageheight/4);
$color =imagecolorallocate ($numimage, Mt_rand (0,150), Mt_rand (0,150), Mt_rand (0,150));
Imagestring ($numimage, 5, $x, $y, $num [$i], $color);
}

for ($i =0; $i <200; $i + +) {
$randcolor =imagecolorallocate ($numimage, Rand (200,255), Rand (200,255), Rand (200,255));
Imagesetpixel ($numimage, Rand ()%70,rand ()%20, $randcolor);
}
Imagepng ($numimage);
Imagedestroy ($numimage);
?>

Take a look at an example of generating a verification code

Generate a Captcha picture

Session_Start ();

Header ("Content-type:image/png");

Srand (Double) microtime () *1000000);

$roundnum =rand (1000,9999);

Put a random number in the session for later use

$_session["Sessionround"]= $roundnum;

$im = Imagecreate (58,28);

$red = Imagecolorallocate ($im, 255,0,0);

$blue = Imagecolorallocate ($im, 0,255,0);

Local area padding, equivalent to background

Imagefill ($im, 68,30, $red);

Drawing a four-bit integer verification code into a picture

Imagestring ($im, 5, 8, $roundnum, $blue);

for ($i =0; $i <50; $i + +)//Add interfering pixels

{

Imagesetpixel ($im, Rand ()%70, Rand ()%30, $black);

}

Imagepng ($im);

Imagedestroy ($im);

?>

HTML Call method

Verification Code

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