查看PHP脚本所占用的内存：memory_get_usage()

有时候我们想知道当前PHP脚本所使用的内存是多少，怎么办呢？其实很简单，就是使用PHP内置函数memory_get_usage()。

/* Example 1. A memory_get_usage() example */
// This is only an example, the numbers below will
// differ depending on your system

echo memory_get_usage() . "\n"; // 36640

$a = str_repeat("Hello", 4242);
echo memory_get_usage() . "\n"; // 57960

unset($a);
echo memory_get_usage() . "\n"; // 36744

memory_get_usage()函数返回的值，单位是byte，即该时间点PHP脚本使用的内存。下面是PHP手册中该函数的说明：

int memory_get_usage ( [bool real_usage] )
Returns the amount of memory, in bytes, that’s currently being allocated to your PHP script.
real_usage: Set this to TRUE to get the real size of memory allocated from system. 
If not set or FALSE only the memory used by emalloc() is reported.