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子类指针，父类指针分别调用virtual函数，与非virtual函数

virtual函数，通过指针调用的是子类函数
非virtual函数，取决于指针的类型

class Person {
public:void Print(){cout << "Person" << endl;}virtual void VirtualPrint(){cout << "VirtualPrint Person" << endl;}
};class Studen : public Person {
public:void Print(){cout << "Student" << endl;}virtual void VirtualPrint(){cout << "VirtualPrint Student" << endl;}
};int main()
{Person *p = new Studen();Studen *s = new Studen();p->Print();     // Persons->Print();     // Studentp->VirtualPrint();  // VirtualPrint Students->VirtualPrint();  // VirtualPrint Studentreturn 0;
}

虚函数中尽量不要使用默认参数！！！

class Father {
public:void func1(int val = 100){cout << "Father \t: func1" << "\t" << val << endl;}virtual void func2virtual(int val = 100){cout << "Father \t: func2" << "\t" << val << endl;}
};class Son : public Father {
public:void func1(int val = 200){cout << "Son \t: func1" << "\t" << val << endl;}virtual void func2virtual(int val = 200){cout << "Son \t: func2" << "\t" << val << endl;}
};

当指针类型与实体类型一致时，很容易分清楚其调用规则

void group1()
{Father *f = new Father();Son *s = new Son();f->func1();s->func1();// Father  : func1 100// Son     : func1 200f->func1(300);s->func1(300);// Father  : func1 300// Son     : func1 300f->func2virtual();s->func2virtual();// Father  : func2 100// Son     : func2 200f->func2virtual(300);s->func2virtual(300);// Father  : func2 300// Son     : func2 300
}

当指针类型与实体类型不一致时，很不容易分清楚其调用规则
在virtual函数中使用默认参数，因为virtual是动态绑定，导致都是调用了子类函数，但是默认参数是根据指针类型来使用的

void group2()
{Father *f = new Son();Son *s = new Son();f->func1();s->func1();// Father  : func1 100// Son     : func1 200f->func1(300);s->func1(300);// Father  : func1 300// Son     : func1 300// virtual func use dynamic func, but use ptr default args// 重点处f->func2virtual();s->func2virtual();// Son     : func2 100// Son     : func2 200// virtual func use dynamic func, use given argsf->func2virtual(300);s->func2virtual(300);// Son     : func2 300// Son     : func2 300
}