C++ 基础考考自己，看程序写出输出

最新推荐文章于 2024-09-16 08:03:34 发布

六六哥

最新推荐文章于 2024-09-16 08:03:34 发布

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文章标签： c++ struct class delete output c

本文链接：https://blog.youkuaiyun.com/eric_liufeng/article/details/6189895

本文探讨了C++中不同类与结构体在构造与析构过程中的顺序规则，包括多重继承、虚继承及类成员的影响，并通过具体示例展示了这些规则的实际应用。

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class NoVirtualClass
{
public:
    NoVirtualClass()
    {
       std::cout << " NoVirtualClass " << endl;
    }

    ~NoVirtualClass()
    {
       std::cout << " ~NoVirtualClass " << endl;
    }
};

class VirtualClass
{
public:
    VirtualClass()
    {
       std::cout << " VirtualClass " << endl;
    }

    ~VirtualClass()
    {
       std::cout << " ~VirtualClass " << endl;
    }
};

class subClass: public NoVirtualClass, virtual public VirtualClass 
{
public:
    subClass()
    {
        std::cout << " subClass" << endl;
    }
    
    ~subClass()
    {
        std::cout << " ~subClass" << endl;
    }
};

class A
{
public:
   A()
   {
     std::cout << "A" << endl;
   }

   ~A()
   {
     std::cout << "~A" << endl;
   }

};

class C
{
public:
   C()
   {
     std::cout << "C" << endl;
   }

   ~C()
   {
     std::cout << "~C" << endl;
   }

};


class B: public A
{
public:
   B()
   {
     std::cout << "B" << endl;
   }

   ~B()
   {
     std::cout << "~B" << endl;
   }

private:

   C c;

};


struct stA
{
    stA()
    {
       cout << "stA" << endl;
    }
};


struct stB : stA
{
    stB()
    {
       cout << "stB" << endl;
    }
};

struct stC
{
    stC()
    {
       cout << "stC" << endl;
    }
};


struct stD: stB
{
    stD()
    {
       cout << "stD" << endl;
    }

};

struct stE
{
    struct stA a;
    struct stC c;
    struct stD d;
    
    
    stE()
    {
       cout << "stE" << endl;
    }

};

void funRec(int i)
{
   if(i < 5)
   {
     funRec(++i);
   }
   
    cout << " " << i ;

    return;
}


int main(void)
{
    subClass sub;

    volatile char *pvch = new volatile char[10];
    delete pvch;

    cout << endl;

    B b;

    cout << endl;

    struct stE e;

    cout << endl;

    funRec(1);

    cout << endl;
    cout << endl;




    return 0;
}

Output:

 VirtualClass 
 NoVirtualClass 
 subClass

A
C
B

stA
stC
stA
stB
stD
stE

 5 5 4 3 2

~B
~C
~A
 ~subClass
 ~NoVirtualClass 
 ~VirtualClass

刘峰六点评：

(1) 如果有多个父类，其中有虚继承的情况下，不管初始化列表的顺序如何，都会先初始化虚继承的基类，在初始化非虚继承的基类
(2) 如果有类中含有类成员，那么顺序是(1) 基类 (2) 子类类成员（3）子类

(3) 如果有递归调用，函数的局部变量不会随递归调用的对局部变量的改变而改变，当时是几就是几