Detailed tutorial on generating verification code in php_PHP tutorial

This article provides a detailed tutorial on generating verification codes in PHP. The first part is about generating the core verification code, and the second part is a method of generating and calling it.

//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);
?>

Let’s take a look at an example of generating a verification code

//Generate verification code image

session_start();

header("content-type: image/png");

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

$roundnum=rand(1000,9999);

//Save the random number into 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 filling, equivalent to background

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

//Draw the four-digit integer verification code into the picture

imagestring($im, 5, 10, 8, $roundnum, $blue);

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

          {

imagesetpixel($im, rand()%70, rand()%30, $black);

}

imagepng($im);

imagedestroy($im);

?>

html call method

Verification code