Template engine {var} doesnt work - php

Question

I have made a template system but the {var} doesnt output the worth.
It just output {var}.
Here is my template class:
<?php
class Template {
public $assignedValues = array();
public $tpl;
function __construct($_path = '')
{
if(!empty($_path))
{
if(file_exists($_path))
{
$this->tpl = file_get_contents($_path);
}
else
{
echo 'Error: No template found. (code 25)';
}
}
}
function assign($_searchString, $_replaceString)
{
if(!empty($_searchString))
{
$this->assignedValues[strtoupper($_searchString)] = $_replaceString;
}
}
function show()
{
if(count($this->assignedValues) > 0)
{
foreach ($this->assignedValues as $key => $value)
{
$this->tpl = str_replace('{'.$key.'}', $value, $this->tpl);
}
}
echo $this->tpl;
}
}
?>
And here is what I execute on the index:
<?php
require_once('inc/classes/class.template.php');
define('PATH', 'tpl');
//new object
$template = new Template(PATH.'/test.tpl.html');
//assign values
$template->assign('title', 'Yupa');
$template->assign('about', 'Hello!');
//show the page
$template->show();
?>
I really need some help, if you can help I'd would be very grateful.

Answer 1

Instead of line:
$this->assignedValues[strtoupper($_searchString)] = $_replaceString;
You should have:
$this->assignedValues[$_searchString] = $_replaceString;
and it will work.
Of course I assume that inside your template file you have content:
{title} {about}

Answer 2

You should change
$this->assignedValues[strtoupper($_searchString)] = $_replaceString;
to this:
$this->assignedValues["{".$_searchString . "}"] = $_replaceString ;
this will only replace your keywords with values.