sprintf and arrays.

I have a snippet of code that looks something like: if (is_array($p_sub_values)) { foreach ($p_sub_values as $i => $v) { $p_sub_values_str[$i] = "'$v'"; } $s = join(',', $p_sub_values_str); $r = htmlentities(sprintf($tmp[0], $s, ENT_QUOTES); } $tmp[0] in this case contains a string like 'Fred likes %1$s on his %2$s', taking advantage of positional substitution with sprintf. The function call to this snippet can have an optional array passed. My need/desire is to substitute each element of the array into the appropriate position with sprintf. So far I've tried: $r = htmlentities(sprintf($tmp[0], $s, ENT_QUOTES); $r = htmlentities(sprintf($tmp[0], ${$s}, ENT_QUOTES); and a few other bits and pieces, all to no avail (error is about not enough arguments). Is there any way to accomplish this in PHP, or do I need to roll my own substitution code? The array can obviously be anything from a single value to 'unlimited' (though in practice will probably be less than 5). -- My mind not only wanders, it sometimes leaves completely.