- array_values: documentation ( source)
- str_replace: documentation ( source)
- array_keys: documentation ( source)
<?php
$a2 = array(
'{DOMEA}' => 'AAAAAA',
'{DOMEB}' => 'BBBBBBB',
);
$a3 = '
<h1>title</h1>
{DOMEA}
<hr>
{DOMEB}
';
echo str_replace(array_keys($a2), array_values($a2), $a3);