php里对比一下内存消耗

<?php
echo $m1 = memory_get_usage();
echo "<br />";
$var_string="123";
echo $m2 = memory_get_usage()-$m1;
echo "<br />";
$n=123;
echo $m3 = memory_get_usage()-$m1-$m2;
echo "<br />";
$f=123.00;
echo $m4 = memory_get_usage()-$m1-$m2-$m3;
echo "<br />";
$var_array=array("123");
echo $m5 = memory_get_usage()-$m1-$m2-$m3-$m4;
?>