Arithmetic with arrays

[visom]

Hi, I'm making a code that calculates the number of days between two dates. If you punch in 1 for month and 5 for days, and you punch in 2 for month and 1 for day, it should say "27 days between these two dates".

Right now the problem I have is that calculation. My code can record the day/month but doesn't know how to find the difference of days between those two dates.

I believe this is where my problem is

for (int i = inputMonth1; i < inputMonth2; ListMonth[MONTH_LENGTH]++, ListMonth + DifferenceBetweenDays);
	cout << ListMonth[MONTH_LENGTH];

This is my entire code

#include <iostream>
using namespace std;
const int MONTH_LENGTH = 12;
int MinusOne(int);
int DifferenceDays(int);
int Date1;
int ListMonth [MONTH_LENGTH] = {30, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int Month1;
int Month2;
int inputDay1;
int inputDay2;
int main()
{
	int inputMonth1;
	int inputMonth2;
	int Day1;
	int Day2;
	int DifferenceDay1;
	int DifferenceDay2;
	int DifferenceDay3;
	
	cout << "This program calculates the days between two dates" << endl;
	
	cout << "Enter the month (1-12)" << endl;
	cin >> inputMonth1;
	Month1 = MinusOne(inputMonth1);  //This is so if I enter 5 for the month, my program won't identify it as 6.
	cout << ListMonth[Month1] << "days in month " << inputMonth1 << endl;
	cout << "Enter the day of the month" << endl;
	cin >> inputDay1;

	cout << "Enter the month (1-12)" << endl;
	cin >> inputMonth2; 
	Month2 = MinusOne(inputMonth2);
	cout << ListMonth[Month2] << endl;
	cout << "Enter the day of the month" << endl;
	cin >> inputDay2;

	DifferenceDay1 = ListMonth[Month1] - inputDay1; //Adding these two together, then adding it between the months to find days
	DifferenceDay2 = ListMonth[Month2] - inputDay2;
	DifferenceDay3 == DifferenceDay1 + DifferenceDay2;
	
	for (int i = inputMonth1; i < inputMonth2; ListMonth[MONTH_LENGTH]++, ListMonth + DifferenceDay3);
	cout << ListMonth[MONTH_LENGTH];
	//I'm hoping that if I enter 3 for month1 and 5 for day1 (for example) and 5 for month2 and 6 for day2,
	/*it'll add DifferenceDay3 with the number of days from the month(s) in between those two dates, in this case
	50 + 30 and that should get 80 days between from two dates*/
	return 0;
}

int MinusOne(int inputMonth)
{
	int Month;
	Month = (inputMonth - 1);
	return Month;
}

*I added green text to make it easier to know what some of my code does.

Thanks!

[Despairy]

i think you should simplify your algorithm
for saving the ammount of days between two dates you could save
the sum of all the months between those 2 months
and add the days between the end of first month to the day entered
and the numer of days from 2nd month.

but theres another case of entering first month bigger than second
if you get mixed up write again and ill try to help