utf 8 - how to concat two strings in php which are in persian -

the question have string of:

$content=$rows["content"]; 

which retrieved data base.the sting in persian.
want show 150 character.so used:

$content=substr($content,0,150); 

and show still continues need show 3 dots: "..." did:

$content.='...'; 

and when show string echo, 3 dots added appear @ right of last line. persian right left, 3 dots needs appear in left of last line.

i tired 1 two, 1 didn't worked too

    $content =iconv(mb_detect_encoding($content, mb_detect_order(), true), "utf-8", $content);     $content=substr($content,0,150);     $dot='...';     $dot =iconv(mb_detect_encoding($dot, mb_detect_order(), true), "utf-8", $dot);     $content.=$dot; 

i added p tag rtl around texts wanted shown way. this:

            <p dir="rtl">';             echo $content;             echo "...";             echo  '</p>';