求兩日期之間的相隔天數（year，month，day） C語言代碼

    #include<cstdio>

    int isRunNian(int year);

    int DiJiTian(int year,int month,int day);

    void swap(int a,int b);

    int main()

    {

        int year1,month1,day1;

        int year2,month2,day2;

        int sum=0;

        scanf("%d%d%d",&year1,&month1,&day1);

        scanf("%d%d%d",&year2,&month2,&day2);

        if(year1==year2)

        {

            sum = DiJiTian(year1,month1,day1) - DiJiTian(year2,month2,day2);

            if(sum<0)

                sum=-sum;

        }

        else

        {

            if(year1 > year2)

            {

                swap(&year1,&year2);

                swap(&month1,&month2);

                swap(&day1,&day2);

            }

            int a,b,c;

            if(isRunNian(year1))

                a=366-DiJiTian(year1,month1,day1);

            else

                a=365-DiJiTian(year1,month1,day1);


        b=0;  
        int i;  
        for(i=year1+1;i<year2;i++)  
        {  
            if(isRunNian(i))  
                b+=366;  
            else  
                b+=365;  
        }  

        c=DiJiTian(year2,month2,day2);  

        sum=a+b+c;  
    }  

    printf("%d\n",sum);  
    return 0;  
}  



/*判斷閏年的函數*/  
int isRunNian(int year)  
{  
    if(year%400==0||(year%4==0&&year%100!=0))  
        return 1;  
    else  
        return 0;  
}   

/*判斷這一天是這一年的第幾天函數*/  
int DiJiTian(int year,int month,int day)  
{  
    int i,sum=0;  
    for(i=1;i<month;i++)//step1  
    {  
        if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)  
            sum+=31;  
        else if(i==4||i==6||i==9||i==11)  
            sum+=30;  
        else if(i==2)  
        {  
            if(isRunNian(year))  
                sum+=29;  
            else  
                sum+=28;  
        }  
    }  
    sum+=day;//step2  
    return sum;//step3  
}  

/* 交換兩個變量的值的函數 */  
void swap(int *a,int *b)  
{  
    int c;  
    c=*a;  
    *a=*b;  
    *b=c;  
}   </pre>