php 查看数组占用的内存大小

<?php

function convert($size)
{
    $unit=array("b","kb","mb","gb","tb","pb");
    return @round($size/pow(1024,($i=floor(log($size,1024)))),2)." ".$unit[$i];
}

        $start = memory_get_usage();  
        //$a = array_fill(0, 10000, 1);
        $a = [];
        $b = [];
        for ($i=0; $i<10000;$i++){
            $a[] = "chenghuan";
        }
        $mid = memory_get_usage(true); //10k elements array;  
        echo "argv:", convert($mid) , "<br>";  
        for ($j=0; $j<10000;$j++){
            $a[] = "chenghuan";
        }
        $end = memory_get_usage(true); //10k elements array;  
        echo "argv:",  convert($end)  , "<br>";