PHP表单验证：常用的数据类型验证函数

// 验证用户名
if (empty($_POST['username'])) {
    $errors[] = '请输入用户名';
}

// 验证密码
if (empty($_POST['password'])) {
    $errors[] = '请输入密码';
}

$password = $_POST['password'];

if (strlen($password) < 6 || strlen($password) > 12) {
    $errors[] = '密码长度必须在6到12个字符之间';
}

$email = $_POST['email'];

if (!preg_match("/^w+([.-]?w+)*@w+([.-]?w+)*(.w{2,3})+$/", $email)) {
    $errors[] = '邮箱格式不正确';
}

$age = $_POST['age'];

if (!is_int($age)) {
    $errors[] = '年龄必须是整数';
}

$age = $_POST['age'];

if (!filter_var($age, FILTER_VALIDATE_INT, array('options' => array('min_range' => 18, 'max_range' => 60)))) {
    $errors[] = '年龄必须在18到60之间';
}

$birthday = $_POST['birthday'];

if ($birthday && !strtotime($birthday)) {
    $errors[] = '生日格式不正确';
}

$appointment_date = $_POST['appointment_date'];

if ($appointment_date && (strtotime($appointment_date) < time() || strtotime($appointment_date) > strtotime('+7 days'))) {
    $errors[] = '预约日期必须在未来7天内';
}