function to truncate as string using a start and end point
<p>I need to select a portion of a string. I know the start and end point of the string (found using strpos) but I don't know how to select this portion of the string....substr won't work as the string can be different lengths. I need to be able to truncate the string by saying start at this character and end at this character.</p>

<p>I'm sure there's a way to do this but can't seem to finds it in the manual</p>
