问单独的表单，2个特定顺序的操作

EN

<p><span class="error">* required field.</span></p>
<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>
    <input type="submit" name="login" value="Login">
</form>

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if (empty($_POST["name"])) {
        $nameErr = "Name is required";
    } else {
        $name = test_input($_POST["name"]);
        // check if name only contains letters and whitespace
        if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
            $nameErr = "Only letters and white space allowed"; 
        }
    }
}

<form action = "http://website.com/~username/site.php" method="get">
    Name: <input type="text" name="name"><br>
    <Input type="submit">
</form>