C++中static_cast和dynamic_cast

//两种类型转换用于处理类之间的转换，dynamic_cast只能在多态中的使用（有虚函数）
/*
总结：
1 上行指针向下转
	static不报错，编译通过，运行时不报错
	dynamic，编译通过，运行时根据对象会报错

2 子类指针向上转
	符合继承关系，都成功
3 胡乱转
	dynamic运行时报错，static编译不通过
*/
namespace C7N2_Cast
{
	//class base
	class base
	{
	public:
		virtual void vFunc()
		{
			cout << "base vFunc" << endl;
			cout << str << endl;
		}
		void print()
		{
			cout << str << endl;
		}
		base()
		{
			str = "base";
		}
	private:
		string str;
	};
//class derive1 :public base
	class derive1 :public base
	{
	public:
		virtual void vFunc()
		{
			cout << "derive1 vFunc" << endl;
			cout << str << endl;
		}
		void print()
		{
			cout << str << endl;
		}
		derive1()
		{
			str = "derive1";
		}
	private:
		string str;
	};
//class derive2 :public base
	class derive2 :public base
	{
	public:
		virtual void vFunc()
		{
			cout << "derive2 vFunc" << endl;
			cout << str << endl;
		}
		void print()
		{
			cout << str << endl;
		}
		derive2()
		{
			str = "derive2";
		}
	private:
		string str;
	};

	void test()
	{
		base b1, *pbb,*pbd;
		derive1 d1, *pdd, *pdb;
		pbb = &b1;
		pbd = &d1;
		pdd = &d1;
		//pdb = &b1; //error:子类指针不能指向父类对象

//dynamic_cast
//1.1 上行指针 向下转
	//对象符合-->成功
		if (dynamic_cast(pbd) == nullptr) {
			cout << "dynamic_cast(pbd)时失败" << endl;
		}
	//对象不符合-->失败
		if (dynamic_cast(pbd) == nullptr) {
			cout << "dynamic_cast(pbd)时失败" << endl;	//失败
		}
//1.2 子类指针向上转
		//符合继承关系-->成功
		if (dynamic_cast(pdd) == nullptr) {
			cout << "dynamic_cast(pdd)时失败" << endl;
		}
//1.3 胡乱转
	//不满足继承关系-->失败
		if (dynamic_cast(pdd) == nullptr) {
			cout << "dynamic_cast(pdd)时失败" << endl;	//失败
		}

//static_case
//2.1 上行指针  向下转
		//对象符合-->成功
		if (static_cast(pbd) == nullptr) {
			cout << "static_cast(pbd)时失败" << endl;
		}
		//对象不符合-->不报错
		if (static_cast(pbd) == nullptr) {
			cout << "static_cast(pbd)时失败" << endl;
		}
//2.2 子类指针 向上转
		//符合继承关系-->成功
		if (static_cast(pdd) == nullptr) {
			cout << "static_cast(pdd)时失败" << endl;
		}
		//不符合继承关系-->编译不通过
//		if (static_cast(pdd) == nullptr) {
//			cout << "static_cast(pdd)时失败" << endl;	//没有类型检查
//		}
//2.3 胡乱转
		//编译都不通过

	}
}