Question

CIS22A Homework 6

Topic: Chapter 4 & 5

Purpose: Determine if a year is a leap year

Create a new C++ project titled “HW 6” in the CodeBlocks IDE. Use the “Console Application” project option.

Over time, the calendar we use has changed a lot. Currently, we use a system called the Gregorian Calendar and it was introduced in 1582.

The algorithm to determine if a year is a leap year is as follows:

Every year that is exactly divisible by four is a leap year, except for years that are divisible by 100 (century years); but these centurial years are leap years, if they are divisible by 400.

For example, the century years 1700, 1800, and 1900 were not leap years, but the years 1600 and 2000 were because these are divisble by 400.

Leap year calculator

Requirements:

Program must use a sentinel loop (slide 5.8) using value -1 to stop and to run continuously with mutiple year inputs until user enter -1 to stop.

There must be 2 functions: main() and isLeap()

main() function should do the following

-Check that the input year is not less than 1582. Iff it is, display an error message and continue to loop

-If the year is valid, main() calls the isLeap() function and gets a boolean result (true or false). Then it displays a text based on the boolean result.

Write a function using this exact prototype before main() (Chapter 6):

bool isLeap(int year);

This function includes the decision statements to determine if the year is a leap year or not. It returns true or false.

There is no "cin", no "cout", and no loop in this function. It only has "if / else" statement and return.

The function definiton should be put after main().

Here are some sample program run

This program determines leap year.

Enter a year after 1582 or enter -1 to exit: 2000

The year 2000 is a leap year.

Enter a year after 1582 or enter -1 to exit: 1600

The year 1600 is a leap year.

Enter a year after 1582 or enter -1 to exit: 1700

The year 1700 is not a leap year.

Enter a year after 1582 or enter -1 to exit: 2003

The year 2003 is not a leap year.

Enter a year after 1582 or enter -1 to exit: 1900

The year 1900 is not a leap year.

Enter a year after 1582 or enter -1 to exit: 1904

The year 1904 is a leap year.

Enter a year after 1582 or enter -1 to exit: 2004

The year 2004 is a leap year.

Enter a year after 1582 or enter -1 to exit: 1004

The year 1004 is not a valid year

Enter a year after 1582 or enter -1 to exit: -1234

The year -1234 is not a valid year

Enter a year after 1582 or enter -1 to exit: 2400

The year 2400 is a leap year.

Enter a year after 1582 or enter -1 to exit: 2800

The year 2800 is a leap year.

Answer 1

#include <iostream>

using namespace std;

bool isLeap(int year);

int main() {
    cout << "This program determines leap year." << endl;
    int year;
    while (true) {
        cout << "Enter a year after 1582 or enter -1 to exit: ";
        cin >> year;
        if (year == -1)
            break;
        if (year < 1582) {
            cout << "invalid year" << endl;
        } else {
            if (isLeap(year)) {
                cout << "The year " << year << " is a leap year." << endl;
            } else {
                cout << "The year " << year << " is not a leap year." << endl;
            }
        }
    }
    return 0;
}

bool isLeap(int year) {
    return ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
}