提交後保留單選按鈕選擇 - PHP

Question

我遇到單選按鈕出現在我的頁面上的問題，任何人都可以告訴我爲什麼在用戶按下提交後不會保留其選擇？

<?php 
session_start(); 
if(isset($_POST['submit'])) 
if(!empty($_POST['diet'])) 
?> 

... 

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> 

<strong>Dietary Requirements:</strong> 
<br><br> 
Vegetarian <input type="radio" name="diet" <?php if (isset($_POST['diet']) && $_POST['diet']=="Vegetarian") echo "checked";?> value="Vegetarian"> 
<br><br> 
Vegan <input type="radio" name="diet" <?php if (isset($_POST['diet']) && $_POST['diet']=="Vegan") echo "checked";?> value="Vegan"> 
<br><br><br> 

... 

<input type="submit" id="submit" name="submit" value="Submit"> 

確認頁：

<b>Dietary Requirements: </b> 
<br><br><?php if(isset($_SESSION['diet'])) echo $_SESSION['diet']; ?> 

我有另一組下面的飲食要求單選按鈕，它的功能和保留其值精細提交後，所以我不明白爲什麼膳食需求單選按鈕的arent加工。

這裏是一個清晰的功能單選按鈕：

<strong> VIP area* : </strong> <br><br> 
Yes (+£5) <input type="radio" name="vip" <?php if (isset($vip) && $vip=="Yes") echo "checked";?> value="Yes"> 
<br><span id="vip" class="error"><?php echo $vipErr;?></span><br> 
No <input type="radio" name="vip" <?php if (isset($vip) && $vip=="No") echo "checked";?> value="No"> 
<br><br><br> 

Answer 1

我覺得你在尋找這樣的事情：

<?php 
    session_start(); 

    if(isset($_POST['submit'])) { 
     if(!empty($_POST['diet'])) 
      $_SESSION['diet'] = $_POST['diet']; 
    } 

    if(isset($_SESSION['diet'])) 
     echo $_SESSION['diet'] 
?> 


<form action="" method="post"> 
    <strong>Dietary Requirements:</strong> 
    <br><br> 
    Vegetarian <input type="radio" name="diet" <?php if (isset($_POST['diet']) && $_POST['diet']=="Vegetarian") echo "checked";?> value="Vegetarian"> 
    <br><br> 
    Vegan <input type="radio" name="diet" <?php if (isset($_POST['diet']) && $_POST['diet']=="Vegan") echo "checked";?> value="Vegan"> 
    <br><br><br> 
    <input type="submit" name="submit"> 
</form>