php查看一个变量的占用内存的实例代码

<?php
echo memory_get_usage() , '<br>';
$start = memory_get_usage();
$a = Array();
for ($i=0; $i<1000; $i++) {
$a[$i] = $i + $i;
}
$mid = memory_get_usage();
echo memory_get_usage() , '<br>';
for ($i=1000; $i<2000; $i++) {
$a[$i] = $i + $i;
}
$end = memory_get_usage();
echo memory_get_usage() , '<br>';
echo 'argv:', ($mid - $start)/1000 ,'bytes' , '<br>';
echo 'argv:',($end - $mid)/1000 ,'bytes' , '<br>';
echo 'Memory:', ($mid - $start)/1024 ,'k' , '<br>';
echo 'Memory:',($end - $mid)/1024 ,'k' , '<br>';
输出是:
389336
418056
442632
argv:28.72bytes
argv:24.576bytes
Memory:28.046875k
Memory:24k

<?php
$start = memory_get_usage();
$a = array_fill(0, 10000, 1);
$mid = memory_get_usage(); //10k elements array;
echo 'argv:', ($mid - $start )/10000,'byte' , '<br>';
echo 'Memory:', ($mid - $start)/1024 ,'k' , '<br>';
$b = array_fill(0, 10000, 1);
$end = memory_get_usage(); //10k elements array;
echo 'argv:', ($end - $mid)/10000 ,'byte' , '<br>';
echo 'Memory:',($end - $mid)/1024 ,'k' , '<br>';
得到:
argv:54.5792byte
argv:54.5784byte

argv:39.736byte
Memory:388.046875k
argv:39.736byte
Memory:388.046875k

$start_memory = memory_get_usage();
$foo = "Some variable";
echo memory_get_usage() - $start_memory;