Why is my code adding 93 days to the output? - c++

Question

I have a c++ assignment that asks to enter one date and second date and find the number of days between the two, including leap years. My code displays the correct values for two dates, however when tested for 1/2/3 to 3/21/12345, it displays 4507994, which is 93 more days than the correct value of 4507901. Why is this happening? I am including cstdlib and iostream
using namespace std;
bool isLeapYear (int year)
{
bool tf;
if (year%4 !=0)
{
tf = true;
}
else if (year%4 == 0)
{
if (year%1000 == 0)
{
if (year %400 == 0)
{
tf = false;
}
else
{
tf = true;
}
}
tf = false;
}
return tf;
}
int last_day(int month, int year)
{
int lday;
if (month == 2)
{
if (isLeapYear (year) == false)
{
lday = 29;
}
else
{
lday = 28;
}
}
else if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8|| month == 10 || month ==12)
{
lday = 31;
}
else if (month == 4 || month == 6 || month == 9 || month == 11)
{
lday = 30;
}
return lday;
}
void howlongwait (int &month, int &day, int &year)
{
if (day == last_day(month, year))
{
if (month == 12 && day == 31)
{
month = 1;
day = 1;
year = year+1;
}
else
{
month = month+1;
day = 1;
year = year;
}
}
else
{
month = month;
day = day+1;
year = year;
}
}
int main()
{
int month, month2, day2, day, year, year2;
int days = 0;
char trash, garb, garb2, trash2;
cout << "Enter start date (no spaces): " << endl;
cin >> month >> trash >> day >> garb >> year;
cout << "Enter end date (no spaces): " << endl;
cin >> month2 >> trash2 >> day2 >> garb2 >> year2;
if (year2 < year)
{
cout << "Never..." << endl;
return 0;
}
else
{
while ((month != month2) || (day != day2) || (year != year2))
{
howlongwait (month, day, year);
days=days+1;
}
}
cout << "You have to wait " << days << " days" << endl;
}
`

Answer 1

isLeapYear should be fixed like this:
bool isLeapYear (int y)
{
return y%4 == 0 && (y%400 == 0 || y%100 != 0);
}
and please replace isLeapYear (year) == false to isLeapYear (year) == true.
Your version of isLeapYear is:
year%1000 == 0 should be year%100 == 0
corresponding else is missing
flip true and false, or change the function name if you need