C++系统自己主动生成默认构造函数的情况

(1) 基类存在默认构造函数

class CBaseClass

{

public:



CBaseClass()

{

m_i = 0;

}



private:



int m_i;

};





class CDriveClass: public CBaseClass

{

public:



void func()

{

}



private:



};

(2) 成员变量存在默认构造函数

class CTestClass

{

public:



CTestClass()

{

m_i = 1;

}



private:



int m_i;

};



class CDriveClass

{

public:

 void func()

{

}



private:



CTestClass mTestClass;

};

(3) 存在虚函数：初始化虚函数指针

class CDriveClass: virtual public CBaseClass  //: public CBaseClass

{

public:



 void func()

{

}



};

(4) 存在虚基类：初始化虚基类指针

class CBaseClass

{

};





class CDriveClass: virtual public CBaseClass

{

public:



void func()

{

}

};

详细能够查看反汇编代码：Visual Stdio 2010编译器中：Debug->windows->Disassembly

--汇编代码

CDriveClass d;

002613DE  push        1  

002613E0  lea         ecx,[d]  

002613E3  call        CDriveClass::CDriveClass (261136h)