PHPCMS 인증코드가 생성되지 않으면 어떻게 해야 하나요?

<?php
phpinfo();
?>

sudo apt-get install php-gd
sudo apt-get install php-freetype

function create_verify_code() {
    $width = 100;
    $height = 30;
    $code = '';
    
    $image = imagecreatetruecolor($width, $height);
    $white = imagecolorallocate($image, 255, 255, 255);
    imagefill($image, 0, 0, $white);
    
    $code_chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
    
    for ($i = 0; $i < 5; $i++) {
        $code .= $code_chars[rand(0, strlen($code_chars) - 1)];
    }
    
    $_SESSION['verify_code'] = $code; // 存储验证码到session中
    
    $font = 'path/to/your/font.ttf'; // 指定字体文件路径
    $font_size = 16;
    $text_color = imagecolorallocate($image, 0, 0, 0);
    
    for ($i = 0; $i < strlen($code); $i++) {
        imagettftext($image, $font_size, rand(-10, 10), 15 + ($i * 20), 20, $text_color, $font, $code[$i]);
    }
    
    header('Content-Type: image/png');
    imagepng($image);
    imagedestroy($image);
}