常函数和常对象的应用

#include <iostream>
#include <string>
using namespace std;

class student
{
private:
    string name;
    int age;
public:
    student(){}
    student(string name,int age)
    {
        this->name = name;
        this->age = age;
    }

    string getName()
    {
        return this->name;
    }

    int getAge()
    {
        return this->age;
    }

#if 1
    void showStudent()const //常函数,常函数重载
    {
//        this->name = "zhangsan";//error,常函数中不允许修改类的数据成员的值
        cout << "void showStudent()const" << endl;
        cout << this->name << " " << this->age <<endl;
    }

#endif

#if 0
    void showStudent()  //一般函数
    {
        this->name = "zhangsan";    //一般函数中允许修改变量的值
        cout << "void showStudent()" <<endl;
        cout << this->name << " " << this->age <<endl;
    }
#endif
};

#if 0
int showint(int num1) const //error：常函数只能存在于类中
{
    cout << num1 << endl;
}
#endif

int main()
{
    student stu("zhangsan",22); //一般对象，可以调用非常函数，也可以调用常函数
    stu.showStudent();

    const student stu2("lisi",33);  //常对象,不能修改对象的值
    const int i = 10;
    stu2.showStudent();
}