在PHP变量中回显字符串，在注释中[关闭]

I have some (simplified) PHP config for a DB connection.

<?php
/* 
<CONFIG application="Example" version="1.1">
    <Database>
        <Driver>MYSQL</Driver>
        <Host>http://example.com</Host>
        <Port>3306</Port>
        <Database>qwerty</Database>
        <Username>usr</Username>
        <Password>hackme</Password>
    </Database>
</CONFIG>
*/
?>

How can I populate the host, in the comments with a variable from an array, $serv["host"]

Here's my attempt...

<?php $serv["host"] = "http://example.com"; ?>

<?php
/* 
<CONFIG application="Example" version="1.1">
    <Database>
        <Driver>MYSQL</Driver>
        <Host>$serv["host"]</Host>
        <Port>3306</Port>
        <Database>qwerty</Database>
        <Username>usr</Username>
        <Password>hackme</Password>
    </Database>
</CONFIG>
*/
?>

I've tried various concatenation and echo combinations, but it either doesn't compile properly or prints out my DB connection details. I need to keep these comments because the code I'm editing seems to require it.

<?php
$serv = array(
    'host' => 'http://example.com';
);
?>

<CONFIG application="Example" version="1.1">
    <Database>
        <Driver>MYSQL</Driver>
        <Host><?php echo $serv['host']; ?></Host>
        <Port>3306</Port>
        <Database>qwerty</Database>
        <Username>usr</Username>
        <Password>hackme</Password>
    </Database>
</CONFIG>

You could make PHP create a file consisting of your commented out (out-commented?) code and include it then.

<?php $serv["host"] = "http://example.com"; ?>

<?php
$dbcon = "
/* 
<CONFIG application="Example" version="1.1">
    <Database>
        <Driver>MYSQL</Driver>
        <Host>" . $serv["host"] . "</Host>
        <Port>3306</Port>
        <Database>qwerty</Database>
        <Username>usr</Username>
        <Password>hackme</Password>
    </Database>
</CONFIG>
*/";
$f = fopen("comment.php", 'w');
fwrite($f, $dbcon);
fclose($f);
include("comment.php");

?>

You might have to adjust destination and include paths as well as file system permissions, of course. Make sure that it's not readable/guessable from the document root, though. I'd be interested to hear if that actually works.