返回带结构的函数时，为什么会出现计算错误？

Question

I am trying to find the number of elapsed days between two dates. However, with some dates the program prints the wrong number of days between 2 dates.

The formula for number of elapsed days is: N=1461 xf(year,month) / 4+ 153 xg(month)/5 +day

In my program, I have f and g defined as functions that return different values of years and months depending on what the user inputs.

The main problem probably lies with how I scanned the user input with the local variables in the date structure.

N1 is the number of elapsed days for the 1st date. N2 is for the second date.

Below is my written code:

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
struct date {
        int month;
        int day;
        int year;
    };

int f( int theyear,  int themonth){
    if (themonth <=2)
        theyear = theyear-1;
    else
        theyear =theyear; 
    return theyear;
}

int g( int Month){
    if (Month<=2)
        Month=Month+13;
    else 
        Month = Month+1;

    return Month;
}

int main()

{

    struct date time1, time2;
    int N1; int N2;



    printf("Enter time1 (mm,dd,yyyy): ");
    scanf("%i%i%i", &time1.month, &time1.day, &time1.year);

    printf("Enter time2 (mm,dd,yyyy): ");
    scanf("%i%i%i", &time2.month, &time2.day, &time2.year);
    N1=1461 * f(time1.year,time1.month) / 4 + 153 * g(time2.month) / 5 +3;
    N2 = 1461 * f(time2.year,time2.month)/4 +153 * g(time2.month)/5 +21;



    printf("%d \n",abs(N1 -N2));

    return 0;

}

Thank you very much. :)

Sample input/output:

Enter time1 (mm,dd,yyyy): 04 10 1994 Enter time2 (mm,dd,yyyy): 03 10 1994 18

As you can see, it prints out 18. However, it is supposed to be the number of days in a month.

Answer 1

change

N1=1461 * f(time1.year,time1.month) / 4 + 153 * g(time2.month) / 5 +3;
N2 =1461 * f(time2.year,time2.month)/4 +153 * g(time2.month)/5 +21;

to

N1=1461 * f(time1.year,time1.month) / 4 + 153 * g(time1.month) / 5 + time1.day;
N2 =1461 * f(time2.year,time2.month)/4 +153 * g(time2.month)/5 + time2.day;

?