在构造函数中从键盘输入值

方法一：利用istream

      

#include<iostream>using namespace std;class Date{private:    int d,m,y;public:    Date(istream &in);};int main(){    Date my_date(cin);    my_date.show();}Date::Date(istream &in){    in >> y >> m >> d;}

方法二：直接利用cin输入

#include<iostream>using namespace std;class Date{private:    int d,m,y;public:    Date();    void show()const;};int main(){    Date my_date;    my_date.show();}Date::Date(){    int a,b,c;    cin >> a >> b >> c;    y = a;    m = b;    d = c;}void Date::show()const{    cout << Date::d << endl;}