C++实现万年历小功能

#include<iostream>
#include<windows.h>
#include<iomanip>
using namespace std;
int number;       //菜单键
int year, month, day;   //年、月、日
int i, j, t;       //for循环用的量
int s;          //星期X
char c;         //存放随机输入的数字，以实现“按任意键返回主菜单”的功能
char months[] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };   //平年每个月的天数
void Pos(int x, int y);   //光标位置
void menu();        //主菜单函数
void runnian();       //如是闰年则变第二个月天数28为29
void oneyear();       //输出一整年的年历
void onemonth();      //输出一个月的月历
void xianshiweek();     //显示星期数
void Pos(int x, int y)//光标位置 
{
 COORD pos;
 HANDLE hOutput;
 pos.X = x;
 pos.Y = y;
 hOutput = GetStdHandle(STD_OUTPUT_HANDLE);
 SetConsoleCursorPosition(hOutput, pos);
}
void menu()//主菜单函数
{
 Pos(40, 3);
 cout << "***********************************" << endl;
 Pos(40, 4);
 cout << "*     欢迎使用万年历     *" << endl;
 Pos(40, 5);
 cout << "*     ---made by pjr     *" << endl;
 Pos(40, 6);
 cout << "***********************************" << endl;
 Pos(20, 8);
 cout << "操作键：" << endl;
 Pos(20, 9);
 cout << "1.显示一年的年历" << endl;
 Pos(20, 10);
 cout << "2.显示一月的月历" << endl;
 Pos(20, 11);
 cout << "3.显示某一天是星期几" << endl;
 Pos(20, 12);
 cout << "0.退出" << endl;
 Pos(20, 14);
 cout << "请输入操作键(0~3):";
 cin >> number;
 if (number < 0 || number>3)
 {
 system("cls");
 Pos(20, 15);
 cout << "输入数字无效,请重新输入!" << endl;
 menu();
 }
}
void runnian()   //如是闰年则变第二个月天数28为29
{
 cin >> year;
 if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0))   //闰年判断公式
 {
 months[2] = 29;
 }
}
void oneyear()   //输出一整年的年历
{
 cout << "请输入年份：";
 runnian();
 system("cls");   //清屏
 cout << "请输入年份：" << year << endl << endl;
 s = (year - 1 + (year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + 1) % 7;   //该年1月1日的星期数
 for (i = 1; i <= 12; i++)
 {
 cout << i << "月份的月历如下:" << endl;
 cout << setw(6) << "日" << setw(6) << "一" << setw(6) << "二" << setw(6) << "三" << setw(6) << "四" << setw(6) << "五" << setw(6) << "六" << endl;
 for (j = 0; j < s; j++)
 {
  cout << setw(6) << " ";
 }
 for (t = 1; t <= months[i]; t++)
 {
  cout << setw(6) << t;
  s = (s + 1) % 7;
  if (s % 7 == 0)   //当打印到星期六时，换行
  {
  cout << endl;
  }
 }
 cout << endl;
 }
 fflush(stdin);
 cout << "请按任意键返回主菜单:";
 cin >> c;
 system("cls");
 menu();
}
void onemonth()//输出一个月的月历
{
 int s = 0;
 cout << "请输入年份：";
 runnian();
 cout << "请输入月份：";
 cin >> month;
 system("cls");
 cout << "请输入年份：" << year << endl << endl;
 cout << "请输入月份：" << month << endl << endl;
 for (i = 1; i <= month - 1; i++)
 {
 s = s + months[i];   //该年1月1日到所求日期前一天的天数
 }
 s = (year - 1 + (year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + 1 + s) % 7;   //所求日期的星期数
 cout << month << "月份的月历如下:" << endl;
 cout << setw(6) << "日" << setw(6) << "一" << setw(6) << "二" << setw(6) << "三" << setw(6) << "四" << setw(6) << "五" << setw(6) << "六" << endl;
 for (j = 0; j < s; j++)
 {
 cout << setw(6) << " ";
 }
 for (t = 1; t <= months[month]; t++)
 {
 cout << setw(6) << t;
 s = (s + 1) % 7;
 if (s % 7 == 0)
 {
  cout << endl;
 }
 }
 cout << endl;
 cout << "请按任意键返回主菜单:";
 cin >> c;
 system("cls");
 menu();
}
void xianshiweek()   //显示星期数
{
 int s = 0;
 cout << "请输入年份：";
 runnian();
 cout << "请输入月份：";
 cin >> month;
 cout << "请输入日期：";
 cin >> day;
 system("cls");
 cout << "请输入年份：" << year << endl << endl;
 cout << "请输入月份：" << month << endl << endl;
 cout << "请输入日期：" << day << endl << endl;
 for (i = 1; i <= month - 1; i++)
 {
 s = s + months[i];
 }
 s = (year - 1 + (year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + day + s) % 7;
 cout << "显示的星期数如下:" << s << endl;
 cout << endl;
 cout << "请按任意键返回主界面:";
 cin >> c;
 system("cls");
 menu();
}
int main()//主函数
{
 setlocale(LC_ALL, "chs");//转中文
 menu();
 while (number != 0)
 {
 switch (number)
 {
 case 1:
 {
  oneyear();
  break;
 }
 case 2:
 {
  onemonth();
  break;
 }
 case 3:
 {
  xianshiweek();
  break;
 }
 }
 months[2] = 28; //把months[2]变为初值
 }
 if (number == 0)
 {
 system("pause");
 }
 return 0;
}