《C++》多态

多态

多态分为两种：

• 静态多态：函数重载 和 运算符重载 属于静态多态，复用函数名
• 动态多态：派生类 和 虚函数 实现运行时多态

• 静态多态函数地址早绑定--编译阶段确定函数地址
• 动态多态函数地址晚绑定--运行阶段确定函数地址

virtual   //修饰虚函数，使之变为动态

多态特点

• 代码结构清晰
• 可读性强
• 利于前期和后期的扩展及维护

练习--计算器的封装、继承、多态

class Compute
{
public:
	virtual int getResult()
	{
		return 0;
	}

	void assagin(int num1, int num2)
	{
		this->m_num1 = num1;
		this->m_num2 = num2;
	}
	int m_num1;
	int m_num2;
};
class AddCompute : public Compute
{
public :
	int getResult()
	{
		return m_num1 + m_num2;
	}
};
class SubCompute : public Compute
{
public:
	int getResult()
	{
		return m_num1 - m_num2;
	}
};
class MulCompute : public Compute
{
public:
	int getResult()
	{
		return m_num1 * m_num2;
	}
};
class DivCompute : public Compute
{
public:
	int getResult()
	{
		return m_num1 / m_num2;
	}
};
void test()
{
	Compute *p1 = new AddCompute;
	p1->assagin(20, 30);
	cout << p1->m_num1 << " + " << p1->m_num2 << " = " << p1->getResult() << endl;

	Compute *p2 = new SubCompute;
	p2->assagin(20, 30);
	cout << p2->m_num1 << " - " << p2->m_num2 << " = " << p2->getResult() << endl;

	Compute *p3 = new MulCompute;
	p3->assagin(20, 30);
	cout << p3->m_num1 << " * " << p3->m_num2 << " = " << p3->getResult() << endl;

	Compute *p4 = new DivCompute;
	p4->assagin(100,10);
	cout << p4->m_num1 << " / " << p4->m_num2 << " = " << p4->getResult() << endl;

	delete p1; p1 = nullptr;
	delete p2; p2 = nullptr;
	delete p3; p3 = nullptr;
	delete p4; p4 = nullptr;
}
int main()
{
	test();
	system("pause");
	return 0;
}