C++，常成员函数

#include <iostream>
using namespace std;

class Test {
public:
    int x;
    int y;
    void const_m1() const;
    void const_m2() const;
    void m3();
    void m4();
};
/**
 * //1常成员函数不能修改成员变量的值
 * //2常成员函数只能调用常成员函数，不能调用普通成员函数
 * //3普通成员函数可以调用常成员函数
 */
void Test::const_m1(void)const {
    cout<<"start of const_m1() ,call:"<<endl;
    this->const_m2();//可以调用const_m2()
    //this->m3();//error C2662: “Test::m3”: 不能将“this”指针从“const Test”转换为“Test &”
    //this->m4();//error C2662: “Test::m4”: 不能将“this”指针从“const Test”转换为“Test &”
    //this->x = 3;//error C3490: 由于正在通过常量对象访问“x”，因此无法对其进行修改
    cout<<"end of const_m1()"<<endl;
}
void Test::const_m2(void)const {
    cout<<"this is const_m2()"<<endl;
}
void Test::m3(void) {
    cout<<"this is m3(),call:"<<endl;
    this->const_m2();
    cout<<"end of m3()"<<endl;
}
void Test::m4(void) {
    cout<<"this is m4()"<<endl;
    this->x = ;
}

int main(void) {
    Test demo;
    demo.const_m1();
    demo.const_m2();
    demo.m3();
    demo.m4();
    while();
    return ;
}

/*测试结果：
start of const_m1() ,call:
this is const_m2()
end of const_m1()
this is const_m2()
this is m3(),call:
this is const_m2()
end of m3()
this is m4()
*/