学习php表单 主要是想知道 前端通过submit之后 后端是如何进行操作的。现在实现一个效果：点击submit，输入框的信息不会被刷掉；刷新页面，输入框的信息被刷掉(index.php)。
<?php
$nameErr = $emailErr = $genderErr = $websiteErr = '';
$name = $email = $gender = $comment = $website = ""; if ($_SERVER["REQUEST_METHOD"] == "POST") {
if(empty($_POST['name'])){
$nameErr = 'name is required';
}else{
$name = $_POST['name'];
} if(empty($_POST['email'])){
$emailErr = "email is required";
}else{
$email = $_POST['email'];
} if(empty($_POST['website'])){
$website = "";
}else{
$website = $_POST['website'];
} if (empty($_POST["comment"])) {
$comment = "";
} else {
$comment = $_POST["comment"];
} if(empty($_POST['gender'])){
$genderErr = "gender is required";
}else{
$gender = $_POST['gender'];
}
}
?>
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> Name: <input type="text" name="name" value="<?php echo $name?>">
<span class="error">* <?php echo $nameErr;?></span>
<br><br>
E-mail:
<input type="text" name="email" value="<?php echo $email?>">
<span class="error">* <?php echo $emailErr;?></span>
<br><br>
Website:
<input type="text" name="website" value="<?php echo $website ?>">
<span class="error"><?php echo $websiteErr;?></span>
<br><br>
<label>Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment ?></textarea>
<br><br>
Gender:
<input type="radio" name="gender" value="female" <?php if(isset($gender) && $gender == 'female') echo "checked"; ?>>Female
<input type="radio" name="gender" value="male" <?php if(isset($gender) && $gender == 'male') echo "checked"; ?>>Male
<span class="error">* <?php echo $genderErr;?></span>
<br><br>
<input type="submit" name="submit" value="Submit"> </form>
</body>
</html>