php网站验证码

<?php
session_start();

// 生成随机字符串
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$randomString = '';
for ($i = 0; $i < 6; $i++) {
    $randomString .= $characters[rand(0, strlen($characters) - 1)];
}
$_SESSION['captcha'] = $randomString;

// 创建图像
$image = imagecreatetruecolor(150, 50);
$backgroundColor = imagecolorallocate($image, 255, 255, 255);
$textColor = imagecolorallocate($image, 0, 0, 0);

imagefilledrectangle($image, 0, 0, 150, 50, $backgroundColor);
imagettftext($image, 20, 0, 20, 30, $textColor, 'arial.ttf', $randomString);

header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
?>