PHP添加4个otp输入字段的值，以获得用户给出的最终otp代码

<form method="post" action="process.php">
  <label for="otp1">OTP 1:</label>
  <input type="text" id="otp1" name="otp1"><br>
  
  <label for="otp2">OTP 2:</label>
  <input type="text" id="otp2" name="otp2"><br>
  
  <label for="otp3">OTP 3:</label>
  <input type="text" id="otp3" name="otp3"><br>
  
  <label for="otp4">OTP 4:</label>
  <input type="text" id="otp4" name="otp4"><br>
  
  <input type="submit" value="Submit">
</form>

<?php
$otp1 = $_POST['otp1'];
$otp2 = $_POST['otp2'];
$otp3 = $_POST['otp3'];
$otp4 = $_POST['otp4'];

$finalOTP = $otp1 . $otp2 . $otp3 . $otp4;

echo "用户给出的最终OTP代码是：" . $finalOTP;
?>