PHP数据过滤：如何保护用户隐私信息

$filteredInput = strip_tags($userInput);

$filteredInput = htmlspecialchars($userInput, ENT_QUOTES, 'UTF-8');

$filteredInput = trim($userInput);

$emailRegex = '/^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+$/';
if (preg_match($emailRegex, $userInput)) {
    echo "邮箱地址有效";
} else {
    echo "邮箱地址无效";
}

$phoneRegex = '/^d{11}$/';
if (preg_match($phoneRegex, $userInput)) {
    echo "手机号码有效";
} else {
    echo "手机号码无效";
}

$passRegex = '/^(?=.*d)(?=.*[a-z])(?=.*[A-Z])[0-9a-zA-Z]{8,}$/';
if (preg_match($passRegex, $userInput)) {
    echo "密码强度符合要求";
} else {
    echo "密码强度不符合要求";
}

$filteredInput = str_replace(array('!', '@', '#'), '', $userInput);

$filteredInput = substr($userInput, 0, 100);

$filteredInput = mysqli_real_escape_string($conn, $userInput);

if (filter_var($userInput, FILTER_VALIDATE_EMAIL)) {
    echo "邮箱地址有效";
} else {
    echo "邮箱地址无效";
}

if (filter_var($userInput, FILTER_VALIDATE_URL)) {
    echo "URL地址有效";
} else {
    echo "URL地址无效";
}

if (filter_var($userInput, FILTER_VALIDATE_IP)) {
    echo "IP地址有效";
} else {
    echo "IP地址无效";
}