PHP program development example learning form to obtain the value of the text box

<table width="283" height="85" border="1" cellpadding="0" cellspacing="0"> 
<form name="name1" method="post" action="abc.php"> 
<tr> 
<td width="114" height="30" align="center" >管理员:</td> 
<td width="163" height="30" align="center"><input name="username" type="text" /></td> 
</tr> 
<tr> 
<td align="center">密　码：</td> 
<td height="30" align="center"><input name="password" type="password" /></td> 
</tr> 
<tr> 
<td> </td> 
<td height="25">  <input name="submit" type="submit" value="submit" /></td> 
</tr> 
</form> 
</table> 
<?php 
if(!isset($_POST[&#39;submit&#39;])) 
return ; 
if($_POST[&#39;submit&#39;]==&#39;submit&#39;){ 
$username = $_POST[&#39;username&#39;]; 
$password = $_POST[&#39;password&#39;]; 
} 
echo <<<EOT 
<table width="284" border="1" cellpadding="0" cellspacing="0"> 
<tr> 
<td height="25" align="center"> 管理员:$username</td> 
</tr> 
<tr> 
<td height="25" align="center" valign="middle" class="style2">密码：$password</td> 
</tr> 
</table> 
EOT; 
?>