replace the_content(); with echo wpse_limit_content();
function wpse_limit_content() {
$content = $post->post_content;
$MAX_LENGTH = 100;
if ( strlen( $content ) <= $MAX_LENGTH )
return apply_filters('the_content', $content );
$s2 = substr( $content, 0, $MAX_LENGTH );
$s3 = preg_split( "/\s+(?=\S*+$)/", $s2 );
$s4 = $s3[0];
return apply_filters( 'the_excerpt', $s4 );
}
If the string is to long it trims it to give you a nice 100 char excerpt.
you could also just do:
$content = $post->post_content;
if (strlen( $content > 100 ) {
the_excerpt();
} else {
the_content();