C++学习-2023/12/13-C++类型转换

C++类型转换

static_cast

类似C语言强制类型转换
1.可以用做基本数据类型转换
2.把空类型的指针转换为目标指针类型
3.不能转换带有const属性指针

const_cast

提供一个常属性的接口

reinterpret_cast

说基本没用到

dynamic_cast:多态才会接触到

#include <iostream>
struct MM
{
    char* name;
    int age;
    void setData(const char* mmName, int mmAge)
    {
        name = const_cast<char*>(mmName);
        age = mmAge;
    }
    void printfData()
    {
        std::cout << name << "\t" << age << std::endl;
    }

};

//1.基本类型转换
void TestTransform()
{
    //1.基本类型转换
    //C
    int cnum = (int)1.1;
    std::cout << cnum << "\n";
    //C++方式
    int cppNum = int(1.2);
    std::cout << cnum << "\n";
}

void TestStatic_cast()
{
    //C++提供的安全
    double dNum = 1.11;
    //static_cast<要转换的类型>（要转换的东西：表达式也可以）
    int num = static_cast<int>(dNum);
    std::cout << dNum << "\n";
    //const类型转换：增加const
    double eNum= 2.22;
    const int fNum = static_cast<const int>(eNum);
    std::cout << fNum << "\n";

    const int cData = 1;
    //错误用法
    //int* pData = static_cast<int*>(&cData);
    int* pData = const_cast<int*>(&cData);
    std::cout << (*pData)+2000 << "\n";

    MM m1;
    m1.setData("喜德盛", 19);
    m1.printfData();

    char name[20] = "永久";
    MM m2;
    m2.setData(name, 18);
    m2.printfData();
}

int main()
{
    std::cout << "Hello World!\n";
    TestStatic_cast();

}