判斷一年的第幾天

#include<iostream>
using namespace std;
int days(int year,int month,int day);
int main()
{
int YEAR,MONTH,DAY,Totalday;
cin>>YEAR>>MONTH>>DAY;
Totalday=days(YEAR,MONTH, DAY);
cout<<Totalday;


return 0;
}
int days(int year,int month,int day)
{
int iTotalDays=0,flag;
int iDayOfMonth[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
if((year%4==0 && year%100!=0) || year%400==0)
{
flag=1;
}
else
flag=0;
for(int i=1;i<month;i++)
{
iTotalDays+=iDayOfMonth[i];
}
iTotalDays+=day;
if(month>2 && flag==1)
iTotalDays+=1;
return iTotalDays;

}

#include<iostream>
using namespace std;


int sumdays(int year,int month,int day);
int main()
{
int year,month,day,countdays;
cout<<" 請輸入年 月 日:";
cin>>year>>month>>day;
countdays=sumdays(year,month,day);
cout<<countdays;
return 0;
}
 int sumdays(int year,int month,int day)
 {
 int totaldays;
 if(month>12 ||day>31)
 {
 return false;
 }
if((year%4==0 && year%100!=0) ||year%400==0)
{
switch(month)
{
case 1:
totaldays=day;
break;
case 2:
totaldays=31+day;
break;
case 3:
totaldays=31+29+day;
break;
case 4:
totaldays=31+29+31+day;
break;
case 5:
totaldays=31+29+31+30+day;
break;
case 6:
totaldays=31+29+31+30+31+day;
break;
case 7:
totaldays=31+29+31+30+31+30+day;
break;
         case 8:
totaldays=31+29+31+30+31+30+31+day;
break;
case 9:
totaldays=31+29+31+30+31+30+31+31+day;
break;
case 10:
 totaldays=31+29+31+30+31+30+31+31+30+day;
case 11:
totaldays=31+29+31+30+31+30+31+31+30+31+day;
case 12:
totaldays=31+29+31+30+31+30+31+31+30+31+30+day;
}
}
 
else
{
switch(month)
{
case 1:
totaldays=day;
break;
case 2:
totaldays=31+day;
break;
case 3:
totaldays=31+28+day;
break;
case 4:
totaldays=31+28+31+day;
break;
case 5:
totaldays=31+28+31+30+day;
break;
case 6:
totaldays=31+28+31+30+31+day;
break;
case 7:
totaldays=31+28+31+30+31+30+day;
break;
         case 8:
totaldays=31+28+31+30+31+30+31+day;
break;
case 9:
totaldays=31+28+31+30+31+30+31+31+day;
break;
case 10:
 totaldays=31+28+31+30+31+30+31+31+30+day;
case 11:
totaldays=31+28+31+30+31+30+31+31+30+31+day;
case 12:
totaldays=31+28+31+30+31+30+31+31+30+31+30+day;
}
}


return totaldays;


 }

#include<iostream>
using namespace std;


typedef struct mydate
{
int year;
int month;
int day;
}MYDATE;
int main()
{
MYDATE date;
int totaldays=0,months[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
cout<<"輸入年月日:";
cin>>date.year>>date.month>>date.day;
totaldays+=date.day;
for(int i=0;i<date.month;i++)
{
totaldays+=months[i];
}
if(((date.year%4==0 &&date.year%100!=0)||date.year%400==0) && date.month>2)
totaldays+=1;
cout<<totaldays;
return 0;

}