尝试将POST数据添加到字符串

So I have some PHP and I am trying to bring over some data from a previous page's form and make them output within this <<

$firstname = echo $_POST["firstname"];
$email = echo $_POST["email"];

$data = <<<STRING
<contact>
<Group_Tag name="Contact Information">
<field name="First Name">$firstname</field>
<field name="E-Mail">$email</field>
</Group_Tag>
</contact>
STRING;

$firstname = echo $_POST["firstname"];

What black magic are you trying to achieve here?!

Leave that ugly echo keyword out here. You are assigning a variable. Not assigning a result from echo…

$firstname = $_POST["firstname"];
$email = $_POST["email"];

change the line

 $firstname = echo $_POST["firstname"];

with

 echo $firstname = $_POST["firstname"];