how-to-truncate-wordpress-post-titles-with-php

<a href="<?php the_permalink() ?>">
<?php
$thetitle = $post->post_title; /* or you can use get_the_title() */
$getlength = strlen($thetitle);
$thelength = 25;
echo substr($thetitle, 0, $thelength);
if ($getlength > $thelength) echo "...";
?>
</a>