php验证码gif

<?php
session_start();

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

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

$text = generateRandomString();
$_SESSION['captcha'] = $text;

imagefilledrectangle($image, 0, 0, 150, 50, $backgroundColor);
imagettftext($image, 20, 0, 15, 35, $textColor, 'arial.ttf', $text);

header('Content-Type: image/gif');
imagegif($image);
imagedestroy($image);
?>