用汇编的眼光看C++（之类静态变量、静态函数） - c++编程基础

看过设计模式的朋友都知道，我们在设计单件模式的时候离不开类的静态函数。和类的成员变量不同，类的静态变量属于全部类对象数据；同样和类的成员函数不同，类的静态函数属于全部类函数共有。这句话读来想来有一些拗口，不过没有关系，我们可以通过一段代码来说明问题。

（1）静态变量

老规矩，我们首先对类进行初步定义，如下所示：

class employee

{

public:

employee() { }

~employee() {}

static int value;

};

class employee

{

public:

employee() { }

~employee() {}

static int value;

}; 那么，这里出现的value是不是所共有的，我们可以看看相关的函数代码即可：

67: int employee::value = 0;

68:

69: void process()

70: {

00401240 push ebp

00401241 mov ebp,esp

00401243 push 0FFh

00401245 push offset __ehhandler$ process@@YAXXZ (0041f469)

0040124A mov eax,fs:[00000000]

00401250 push eax

00401251 mov dword ptr fs:[0],esp

00401258 sub esp,48h

0040125B push ebx

0040125C push esi

0040125D push edi

0040125E lea edi,[ebp-54h]

00401261 mov ecx,12h

00401266 mov eax,0CCCCCCCCh

0040126B rep stos dword ptr [edi]

71: employee m;

0040126D lea ecx,[ebp-10h]

00401270 call @ILT+35(employee::employee) (00401028)

00401275 mov dword ptr [ebp-4],0

72: employee n;

0040127C lea ecx,[ebp-14h]

0040127F call @ILT+35(employee::employee) (00401028)

73:

74: m.value = 10;

00401284 mov dword ptr [employee::value (00438494)],0Ah

75: n.value = 100;

0040128E mov dword ptr [employee::value (00438494)],64h

76: }

00401298 lea ecx,[ebp-14h]

0040129B call @ILT+0(employee::~employee) (00401005)

004012A0 mov dword ptr [ebp-4],0FFFFFFFFh

004012A7 lea ecx,[ebp-10h]

004012AA call @ILT+0(employee::~employee) (00401005)

004012AF mov ecx,dword ptr [ebp-0Ch]

004012B2 mov dword ptr fs:[0],ecx

004012B9 pop edi

004012BA pop esi

004012BB pop ebx

004012BC add esp,54h

004012BF cmp ebp,esp

004012C1 call __chkesp (004086b0)

004012C6 mov esp,ebp

004012C8 pop ebp

004012C9 ret