Description:
------------
for the function preg_replace() i guess it does comparison and other operation before parse the result from '\\3', '\\2', '\\1' when use a 'general' match pattern like ([1-9][0-9]*)

hence inval() won't work because for string '\\3' or '${3}' the result is always zero.

however 'modifier-like' match pattern like \d, works well.

so what is the fast work around if i need php to parse "\\1" before doing any operation like inval(), or comparison, at the moment?

Reproduce code:
---------------
<?
	$c1 = "2 4 8";
	$cp1 = "/(\d)\s(\d)\s(\d)/e";
	$cr1 = "'\\3*\\2+\\1='.(('\\3')*('\\2')+('\\1'))";
	
	$c2 = "2 4 8";
	$cp2 = "/([1-9][0-9]*)\s([1-9][0-9]*)\s([1-9][0-9]*)/";
	$cr2 = "'\\3*\\2+\\1='.(('\\3')*('\\2')+('\\1'))";
	
	$c3 = "2 4 8";
	$cp3 = "/([1-9][0-9]*)\s([1-9][0-9]*)\s([1-9][0-9]*)/";
	$cr3 = "'\\3*\\2+\\1='.(('\\3')*('\\2')+('\\1'))";
	
	$c4 = "2 4 8";
	$cp4 = "/([1-9][0-9]*)\s([1-9][0-9]*)\s([1-9][0-9]*)/";
	$cr4 = intval('\\3')*intval('\\2')+intval('\\1');
	
	$c5 = "2 4 8";
	$cp5 = "/([1-9][0-9]*)\s([1-9][0-9]*)\s([1-9][0-9]*)/";
	$cr5 = ('\\3' == '${3}' ? '${3}' . ' equals to ' . '\\3' : '${3}' . 'not equals to' . '\\3');
	
	echo (preg_replace($cp1,$cr1,$c1));
	echo ("<br>");
	echo (preg_replace($cp2,$cr2,$c2));
	echo ("<br>");
	echo (preg_replace($cp3,$cr3,$c3));
	echo ("<br>");
	echo (preg_replace($cp4,$cr4,$c4));
	echo ("<br>");
	echo (preg_replace($cp5,$cr5,$c5));
?>

Expected result:
----------------
8*4+2=34
8*4+2=34
8*4+2=34
34
8equals to8

Actual result:
--------------
8*4+2=34
'8*4+2='.(('8')*('4')+('2'))
'8*4+2='.(('8')*('4')+('2'))
0
8not equals to8