使用 PHP isset 进行条目检查后无输出

Question

我正在试验表格，我不知道为什么下面的 cod 不会回显假定的结果。为什么做错了以及如何让它回显用户输入。

<?php

//way to tell if the form has been submitted (If form not submitted, display form again.)
if (!isset($_POST['submit'])){

?>

    <form method="post" action="" />
    <input type="text" name="city" />
    <input type="submit">

</form>

<?php
//Process input
}
else
{

// Retrieve information from form submission.

$username = $_POST['city'];
echo "Your name is $username.";
}
?>

Answer 1

为您的提交按钮命名属性：

//way to tell if the form has been submitted (If form not submitted, display form again.)
if (!isset($_POST['submit'])){

?>

    <form method="post" action="" />
    <input type="text" name="city" />
    <input type="submit" name="submit">

</form>

<?php
//Process input
}
else
{

// Retrieve information from form submission.

$username = $_POST['city'];
echo "Your name is $username.";
}
?>

使用 PHP isset 进行条目检查后无输出

No output after entry check with PHP isset

php

isset