switch 实现年月转换

#include "stdafx.h"
#include <stdlib.h>
#include <stdio.h>
int DayofYear(int year,int month, int day);
void MonthDay(int year,int yearDay,int *pMonth,int *pDay);
void Menu(void);
int dayTab[2][13] = {{0,31,28,31,30,31,30,31,31,30,31,30,31},
                    {0,31,29,31,30,31,30,31,31,30,31,30,31}};
int main()
{
 int year,month,day,yearDay;
 char c;
 Menu();
 c = getchar();
 switch(c)
 {
 case '1':printf_s("please enter year,month,day:");
       scanf_s("%d,%d,%d",&year,&month,&day,3*sizeof(year));
    yearDay = DayofYear(year,month,day);
    printf_s("yearDay = %d ",yearDay);
    break;
 case '2':printf_s("Please enter year,yearDay:");
       scanf_s("%d,%d",&year,&yearDay);
    MonthDay(year,yearDay,&month,&day);
    printf_s("month = %d,day = %d ",month,day);
    break;
 case '3':exit(0);
 default :printf_s("input the error");
 }
    system("pause");
 return 0;
}
int DayofYear(int year,int month,int day)
{
 int i, leap;
 leap = ((year % 4 == 0)&&(year % 100 !=0))||(year % 400 == 0);
 for(i = 1;i < month ;i++)
 {
  day = day +dayTab[leap][i];
 }
 return day;
}
void MonthDay(int year,int yearDay,int *pMonth,int *pDay)
{
 int i, leap;
 leap = ((year % 4 ==0)&&(year %100 !=0))||(year % 400 == 0);
 for(i = 1;yearDay > dayTab[leap][i];i++)
 {
  yearDay = yearDay - dayTab[leap][i];
 }
 *pMonth = i;
 *pDay = yearDay;
}
void Menu(void)
{
 printf_s("1. year/month/day ->yearDay ");
 printf_s("2. yearDay -> year/month/day ");
 printf_s("3. Exit ");
 printf_s("please enter your choice:");
}