How to assign a PHP expression to a PHP variable - php

Question

I need to do something like
$var = "Hello World ..the value is <?php echo 'XYZ' ?>";
Any help will be highly useful. I am stuck in this from the very long time but not able to acheive this. please help
Below is my PHP code that I need to assigned again to php variable (this variable will be passed to return of my ajax call)
<div class="photo-post">
<h4 class="h4-1">Some data...</h4>
<?php
$i=0;
$unique_seq="888094499";
$pic_counter=1;
foreach (glob("target/*".$unique_seq."*") as $filename)
{
$i++;
}
$total_pics=$i;
echo "<div id='post-photo-slider'>";
if($i>1)
{
echo "<a href='#' class='control_next_photo'>></a>";
echo "<a href='#' class='control_prev_photo'><</a>";
}
echo "<ul>";
foreach (glob("target/*".$unique_seq."*") as $filename)
{
echo "<li>";
echo "<div class='photos-slide-container'>";
echo "<img src='".$filename."' width='540px' height='225px'>";
echo "<span class='count-span-photos'>".$pic_counter." of ".$total_pics."</span>";
echo "</div>";
echo "</li>";
$pic_counter++;
}
if ($i==1)
{
echo "<li></li>";
}
echo "</ul>";
echo "</div><!-- post-photo-slider END -->";
echo "<hr class='hr4'>";
?>
</div><!-- photo end -->

Answer 1

you cannot do it in this way
$var = "Hello World ..the value is <?php echo 'XYZ' ?>";
when you return this string to your javascript php code cannot be execute on client side!!!!
why do not return do this simple way?
$var = "Hello World ..the value is " . "XYZ";