源程序：

#include <iostream>

#include <string>

using namespace std;

 

class myDate

{

private:

int year, month, day;

public:

myDate();

myDate(int);   //默认参数，从右向左初始化

myDate(int, int);

myDate(int, int, int);

void show();

};

myDate::myDate() :year(1990), month(9), day(19) {}

myDate::myDate(int y, int m) : day(25)

{

year = y;

month = m;

}

myDate::myDate(int y) : month(12), day(11)

{

year = y;

}

myDate::myDate(int y, int m, int d)

{

year = y;

month = m;

day = d;

}

void myDate::show()

{

cout << "year:" << year << "month:" << month << "day:" << day << endl;

}

int main()

{

myDate M;

myDate N(1982);

myDate P(1992, 5);

myDate Q(2001, 11, 11);

cout << endl;

M.show();

N.show();

P.show(); 

Q.show();

system("pause");

return 1;

}

运行结果：