how do I add dots after full word or end of sentance ...

Hi currently on a website i have this line of code to put in dots after a certain amount of characters in a string...however the client feels this looks messy on their website as it cuts words off..so they want something more clean where it will only add dots after a whole word yet still add 3 dots after so the end-user knows there is more to read... Basically its for my homepage showing a summary of a blog entry but i want to keep the summary to max 2 lines...

here is the code i have currently:

<?php echo strip_tags (substr($row_rsBlog['BlogContent'],0, 50).'...'); ?>

assume that the last word is always going to be truncated and remove it.

here is a sample of how to do that:

<?php 

// strip the tags

$returnString = strip_tags($row_rsBlog['BlogContent']);

//truncate to first 50 characters

$returnString = substr($returnString, 0, 50);

// find the space near the end of the string

$lastSpacePosition = strrpos($returnString," ");

//remove everything from that space to the end

$returnStringWithoutLastWord = substr($returnString,0,$lastSpacePosition);

// echo the result

echo($returnStringWithoutLastWord."..."); 

?>