PHP上传 - 为什么isset($ _ POST ['submit'])始终为FALSE

a20*_*011 7 php

我有以下代码示例upload3.php:

<html>
<head>
<title>PHP Form Upload</title>
</head>
<body>

<form method='post' action='upload3.php' enctype='multipart/form-data'>
    Select a File:
    <input type='file' name='filename' size='10' />
    <input type='submit' value='Upload' />
</form>

<?php

if (isset($_POST['submit']))
{
    echo "isset submit";
}
else 
{
    echo "NOT isset submit";
}

?>

</body>
</html>
Run Code Online (Sandbox Code Playgroud)

代码始终返回"NOT isset submit".为什么会这样?因为相同的脚本upload3.php调用自己?

ash*_*exm 33

您没有名为"
更改"的提交按钮

<input type='submit' value='Upload' />
Run Code Online (Sandbox Code Playgroud)

至:

<input type='submit' value='Upload' name="submit"/>
Run Code Online (Sandbox Code Playgroud)