convert numbers to arabic letters

Hi,im working on ARABIC TTS(text to speech) and i have this program that only could replace one number by arabic letters,so i m asking if there is a better and effective way to convert text containing a lot of numbers and dates to words

 PROGRAM:

        slCharacterEncoding('UTF-8')
        fid = fopen('arabe.txt');       %text is :(3 stars)   النجوم 3        
        b = fread(fid,'uint8')';
        fclose(fid);
        a=dec2bin(b);
        c=dec2hex(b);
        str = native2unicode(b,'UTF-8');
        disp(str);

        fid = fopen('3.txt');        text is :الثلاثة(three)
        b3 = fread(fid,'uint8')';
        fclose(fid);
        str3 = native2unicode(b3,'UTF-8');
        disp(str3);

        nbrasci=abs(str);
for i=1:1:length(str)
   if nbrasci(i)==51;
       str=char([nbrasci(1:i-1),str3,nbrasci(i+1:length(str))]);   str=(three stars) النجوم الثلاثة

   end
end