forever loop... not clearing user input correctly? - c++

Question

when user inputs 'y' or 'Y' for "Do you wish to enter another year? (Y/N): ", loops "the month has 0 days" forever. Why?
I tried to look at the values and it seems like the values stored are being used again. Maybe I am not using cin.clear() correctly?
//variables
bool ucontinue = true; //answer to continue
int year = 0;
int month = 0;
int days = 0;
char answer = 'a';
//loop
while (ucontinue == true)
{
/*
Enter a year (Must be a positive integer): 2016
Enter a month (Must be a between 1 and 12): 2
The month has 29 days.
Do you wish to enter another year? (Y/N): y
*/
//year input
while (year <= 0)
{
cout << "Enter a year (Must be a positive integer): ";
cin >> year;
}
//month input
while (month <= 0)
{
cout << "Enter a month (Must be a between 1 and 12):";
cin >> month;
}
//# of days in the month
cout << "The month has " << days << " days." << endl << endl;
//continue?
while (answer != toupper('y') && answer != toupper('n'))
{
cout << "Do you wish to enter another year? (Y/N): ";
cin >> answer;
answer = toupper(answer);
if (answer == toupper('n'))
{
ucontinue = false;
}
}
cin.clear();
}

Answer 1

you code loops forever because of you while loops the the first time you run the program it works fine but the second time it goes around all the values are set for example the second time you go through the loop this while statement
while (year <= 0)
{
cout << "Enter a year (Must be a positive integer): ";
cin >> year;
}
won't run because year is already greater than 0 and this happens for all the while statements in your code. what would work is if you have do while statements instead of while statements because do while statements will run through the loop once before testing the condition it. like this:
do
{
cout << "Do you wish to enter another year? (Y/N): ";
cin >> answer;
answer = toupper(answer);
if (answer == toupper('n'))
{
ucontinue = false;
}
}while(answer != 'Y' && answer != 'N');

Answer 2

If I understand correctly you do the following:
Enter a year (Must be a positive integer): 2017
Enter a month (Must be a between 1 and 12):5
The month has 0 days.
Do you wish to enter another year? (Y/N): y <ENTER>
and your program loops. What happens it the following:
cin.clear();
is executed and your loop starts again. At this point year and month are still set. So when in the new loop iteration the line
while (year <= 0)
is encountered the condition is false and the loop continues to
while (month <= 0)
for this line the same is true. After that
cout << "The month has " << days << " days." << endl << endl;
is printed and the condition in
while (answer != toupper('y') && answer != toupper('n'))
is checked. As I have just entered y this condition is not true and
cin.clear();
is executed next, after this the loop restarts ad infinitum.

Answer 3

Your programs have many problems
you never updated or input something on the days variable so it will always be 0 as you set it in the beginning of the program
if (answer == toupper('n')) can be reduced to if (answer=='N')