程式碼示例：

#include<stdio.h>

#include<stdlib.h>

int main()

{

int year,month,day;

int leapyear=0;

int daytime=0;

int sum;

int index=0;

static int month_date[12]={31,28,31,30,31,30,31,31,30,31,30,31};

printf("請輸入日期:");

scanf("%d-%d-%d",&year,&month,&day);

printf("請輸入天數:");

scanf("%d",&daytime);

sum=daytime+day;

if(month==2)

{

if(year%400==0||(year%100!=0&&year%4==0))

{

leapyear=1;

month_date[month-1]+=leapyear;//如果是閏年則2月加一天

}

else

{

month_date[month-1] = 28;//如果不是閏年，則二月置為28天

}

printf("%d年的二月份是：%d天\n",year,month_date[month-1]);

}

for(int i=0;i<month;i++ ){

index +=month_date[month-1];

}

index +=day;//計算天數

printf("該日期是第%d天\n",index);

do

{

if(month==2)

{

if(year%400==0||(year%100!=0&&year%4==0))

{

leapyear=1;

month_date[month-1]+=leapyear;

}

else

{

month_date[month-1] = 28;

}

printf("%d年的二月份是：%d天\n",year,month_date[month-1]);

}

if(sum>month_date[month-1])

{

sum-=month_date[month-1];

month++;

if(month==13)

{

year++;

month=1;

}

}

} while(sum>month_date[month-1]);

day=sum;

printf("\n第%d天后是%d-%d-%d",daytime,year,month,day);

return 0;

}