my $max_len = 200; 
 
my $string = ''; 
while (<FILE>) { 
  foreach my $word (split) { 
    if (length($string) + length($word) + 1 > $max_len) { 
      # stop there 
      last; 
    } else { 
      $string .= " $word"; 
    } 
  } 
}