C++的类型转换详细介绍

#include<iostream>
using namespace std;

class Animal
{
public:
 virtual void action()
 {
 cout<<"the action is animal's "<<endl;
 }
};

class Dog:public Animal
{
public:
 virtual void action()
 {
 cout<<"the action is dog's "<<endl;
 }

 void doSwim()
 {
 cout<<"the dog is swimming..."<<endl;
 }
};

class Cat:public Animal
{
public:
 virtual void action()
 {
 cout<<"the action is cat's "<<endl;
 }

 void doTree()
 {
 cout<<"the cat is claming tree..."<<endl;
 }
};

class Desk
{
public:
 void action()
 {
 cout<<"this is Desk, not belong Animal"<<endl;
 }
};

void ObjPlay(Animal *animl)
{
 animl->action();
 Dog *dog = dynamic_cast<Dog *>(animl);
 if(dog!=NULL) //判断是不是dog
 {
 dog->action();
 dog->doSwim();
 }

 Cat *cat = dynamic_cast<Cat *>(animl);
 if(cat!=NULL) //判断是不是cat
 {
 cat->action();
 cat->doTree();
 }
 cout<<"func ObjPlay is exit!!!\n"<<endl;
}

//典型用法 把形参的只读属性去掉
void Opbuf(const char *p)
{
 cout << p << endl;
 //char *p2 = p; err:const char *不能初始化为char *
 //p[0] = 'b'; err:必须是可修改的左值
 char *p2 = const_cast<char*>(p); //去除只读的属相
 p2[0] = 'b';
 cout << p << endl;
}

int main()
{
 //静态类型转化 static_cast<>()
 double d = 3.14159;
 int i1,i2;
 i1 = d; //C中的隐式类型转化
 i2 = static_cast<int>(d); //C++中的静态类型转化
 cout<<"C中类型转化："<<i1<<endl;
 cout<<"C++中类型转化："<<i2<<endl;


 //重新解释类型reinterpret_cast<>()
 char *p = "abcd";
 int *p1 = NULL;
 int *p2 = NULL;
 p1 = (int *)p; //C中强制类型转化
 //p2 = static_cast<int *>(p);  编译报错，类型转化错误，静态类型不能转化指针
 p2 = reinterpret_cast<int *>(p); //C++中的重新解释类型
 cout<<"C中类型转化"<<hex<<*p1<<endl;
 cout<<"C++中类型转化："<<hex<<*p2<<endl;

 //动态类型转换 dynamic_cast<>()
 Animal an;
 Animal *pAn = &an;
 ObjPlay(pAn);

 Dog dog;
 Dog *pDog = &dog;
 ObjPlay(pDog);

 Cat cat;
 Cat *pCat = &cat;
 ObjPlay(pCat);

 Desk desk;
 Desk *pDesk = &desk;
 //Animal *pAn = dynamic_cast<Animal*>(pDesk); 不同的基类指针之间不能相互转化，安全

 //去除变量的只读属性，const_cast<>(),此类型必须是指针
 char buf[100] = "aaaaaaaaaaaa";
 //Opbuf(buf);
 //要保证指针所执行的内存空间能修改才行 若不能修改 还是会引起程序异常
 //Opbuf("dddddddddddsssssssssssssss");

 system("pause");
 return 0;
}