Ok, my book said I can use the following formula to calculate the days between two dates.

N = 1461 x f(year, month) / 4 + 153 g(month /5 + day

where

f(year,month) = year-1 if month <=2

year otherwise

g(month) = month + 13 if month <=2

month +1 otherwise

But then it saids this formula only works for dates after March1, 1900( 1 must be added for dates form March 1, 1800 to February 28, 1900 and2 must be added for dates between March 1, 1700 to February 28, 1800

Now I have to write a program that permits the user to typein two dates and then calculates the number of elapsed days.

Ok this is what I have so far.

Code:

int main () {
struct date {
int month;
int day;
int year;
};
struct date d1, d2, N, N1, N2, x;
int daynumber(struct date d);
int elapsedDays;
int days_between(struct date d1, struct date d2);
printf ("Enter date 1 (MM/DD/YYYY): ");
scanf ("%d/%d/%d", &d1.month, &d1.day, &d1.year);
printF("\n");
if ( d1.month <= 2 )
//suppose to be something with f(year, month).
// if( month <= 2){
// f(year, month) = year - 1; g(month) = month + 13;
{
int year = d1.year - 1;
int month = d1.month + 13;
}
else
{
year = d1.year;
month = d1.month + 1;
}
printf ("Enter date 2 (MM/DD/YYYY): ");
scanf ("%d/%d/%d", &d2.month, &d2.day, &d2.year);
printF("\n");
if ( d2.month <= 2 )
{
year = d2.year - 1;
month = d2.month + 13;
?}
else
{
year = d2.year;
month = d2.month + 1;
}
if( d1 >= 03/01/1800 && d1 <= 02/28/1900)
{
N = N+1;
}
else if( d1 >= 03/01/1700 && d1 <= 02/28/1800)
{
N = N+2;
}
if( d2 >= 03/01/1800 && d2 <= 02/28/1900)
{
N = N+1;
}
else if( d2 >= 03/01/1700 && d2 <= 02/28/1800)
{
N = N+2;
}
// Computes N
int daynumber(struct date d)
{
N1 = 1461 * f(d1.year,d1.month) / 4 + 153 * g(d1.month) / 5 + d1.day;
N2 = 1461 * f(d2.year,d2.month) / 4 + 153 * g(d2.month) / 5 + d2.day;
}
// Computes elapsed days between two dates
int days_between(struct date d1, struct date d2)
{
elapsedDays = N2 - N1;
return elapsedDays;
}
// Function to determine if date d is before date x
int isbefore(struct date d, struct date x);
int isbefore(struct date d, struct date x)
{
if ( d < x )
x = 1;
else
x = 0;
return x;
}
printf ("There are %d days between %d/%d/%d and %d/%d/%d",
elapsedDays, d1.month, d1.day, d1.year, d2.month, d2.day, d2.year);
printF("\n");
return 0;
}

I can not get pass compiling the Program. I pretty new at this and can not figure out my mistakes

Any help will be appreciated, Thanks, Bill