经测试代码如下：
/**
* 获取内存使用信息
*
* @param
* @author 编程之家 jb51.cc jb51.cc
**/
echo "Initial: ".memory_get_usage()." bytes \n";
/* prints
Initial: 361400 bytes
*/
// let's use up some memory
for ($i = 0; $i < 100000; $i++) {
$array []= md5($i);
}
// let's remove half of the array
for ($i = 0; $i < 100000; $i++) {
unset($array[$i]);
}
echo "Final: ".memory_get_usage()." bytes \n";
/* prints
Final: 885912 bytes
*/
echo "Peak: ".memory_get_peak_usage()." bytes \n";
/* prints
Peak: 13687072 bytes
*/
/*** 代码来自编程之家 jb51.cc（jb51.cc） ***/