#!/usr/bin/php  -ddisplay_errors=E_ALL
<?
$NUMBER = 1E5; //adjust from 10...100k. 

//Times below are for NUMBER=1E5 on an i7 3.5GHz CPU.
  
echo "Main scope ReadWrite...                        ";
for ($i = 0; $i< $NUMBER; $i++){
	$data1[$i] = "$i";
}
$t1 = microtime(true);
$n =  count($data1); 
$data1 = $n;
$t2 = microtime(true);
echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #9923 us


echo "Main scope ReadOnly...                         ";
for ($i = 0; $i< $NUMBER; $i++){
	$data2[$i] = "$i";
}
$t1 = microtime(true);
$n =  count($data2); 
$data2_new = $n;
$t2 = microtime(true);
echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #6 us


function f3(){
	global $NUMBER;
	echo "Local variable ReadWrite...                    ";
	for ($i = 0; $i< $NUMBER; $i++){
		$data3[$i] = "$i";
	}
	$t1 = microtime(true);
	$n =  count($data3); 
	$data3 = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #10101 us
}
f3();


function f4(){
	global $NUMBER;
	echo "Local variable ReadOnly...                     ";
	for ($i = 0; $i< $NUMBER; $i++){
		$data4[$i] = "$i";
	}
	$t1 = microtime(true);
	$n =  count($data4);
	$data4_new = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #5 us
}
f4();



$data5 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data5[$i] = "$i";
}
function f5($data5b){
	echo "Pass variable as function arg (ReadWrite)...   ";
	$t1 = microtime(true);
	$n = count($data5b);   
	$data5b = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #15 us
	return ($data5b);
}
f5($data5);



$data6 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data6[$i] = "$i";
}
function f6($data6b){
	echo "Pass variable as function arg (ReadOnly)...    ";
	$t1 = microtime(true);
	$n = count($data6b);   
	$data6b_new = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #14 us
	return ($data6b_new);
}
f6($data6);



$data7 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data7[$i] = "$i";
}
function f7(){
	echo "Use 'global \$var' ReadWrite...                 ";
	$t1 = microtime(true);
	global $data7;
	$n = count($data7);
	$data7 = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #23795 us
}
f7();



$data8 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data8[$i] = "$i";
}
function f8(){
	echo "Use 'global \$var' ReadOnly...                  ";
	$t1 = microtime(true);
	global $data8;
	$n = count($data8);
	$data8_new = $n;
	global $data8_new;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #14541 us
}
f8();


$data9 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data9[$i] = "$i";
}
function f9(){
	echo "Use '\$GLOBALS['var'] ReadWrite...              ";
	$t1 = microtime(true);
	$n = count($GLOBALS['data9']);
	$GLOBALS['data9'] = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #9519 us
}
f9();



$data10 = array();
for ($i = 0; $i< $NUMBER; $i++){
	$data10[$i] = "$i";
}
function f10(){
	echo "Use '\$GLOBALS['var'] ReadOnly...               ";
	$t1 = microtime(true);
	$n = count($GLOBALS['data10']);
	$GLOBALS['data10_new'] = $n;
	$t2 = microtime(true);
	echo round(($t2 - $t1) *1E6, 3). " us.\n\n"; #8 us
}
f10();


echo 	"Conclusions: \n".
	"  * Much faster (1000x) to create a new var than to modify an existing one in-place \n".
	"  * function calls always optimise, whether internally RO or RW\n".
	"  * \$GLOBALS[] perform the same as normal variables - slow for RW, fast for RO.\n".
	"  * global is somewhat slower than GLOBALS for RW, and *also* slower than GLOBALS for RO.\n".
	"  * global for RO is 100x slower than GLOBALS for RO. Bug? \n".
	"\n";