- substr: documentation ( source)
- trim: documentation ( source)
<?php
$str = 'http://visitbeyond.areadigital.org/var/site/storage/images/media/images/china/beijing-urban-outskirts-5d/1.-steep-great-wall/196692-1-eng-GB/1.-steep-great-wall_gallery_large.jpg';
if(substr(trim($str), 0, 35) == 'http://visitbeyond.areadigital.org/'){
$str = 'http://gobeyond.asia/'.substr(trim($str), 35);
}
echo $str;