这个哪里错了
<?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;
?>