- array_slice: documentation ( source)
- implode: documentation ( source)
- explode: documentation ( source)
<?php
$str = 'DisplayText="cf font="Arial" size="10" complexscriptsfont="Arial" complexscriptssize="10" asiantextfont="Arial" fontcolor="595959"">';
$splitted = explode('"', $str);
$splittedSize = count($splitted);
$result = $splitted[0].'"'.implode('"',array_slice($splitted,1,$splittedSize-2)).$splitted[$splittedSize-1].'"';
echo $result;