Question

How to check leap year in C++

Answer 1

#include <iostream>
#include <array>

bool isLeapYear(int year) {
    if (year % 400 == 0)
        return true;
    if (year % 100 == 0)
        return false;
        
    return (year % 4 == 0);
}

int main() {
    std::array<int, 15> years = {
        2000, 2400, 1800, 1900, 2100, 2200, 2300, 2500,
        2008, 2012, 2016, 2020, 2024, 2048, 2032
    };

    for (int year : years) {
        if (isLeapYear(year))
            std::cout << year << " is a leap year.\n";
        else
            std::cout << year << " is not a leap year.\n";
    }
}



/*
run:

2000 is a leap year.
2400 is a leap year.
1800 is not a leap year.
1900 is not a leap year.
2100 is not a leap year.
2200 is not a leap year.
2300 is not a leap year.
2500 is not a leap year.
2008 is a leap year.
2012 is a leap year.
2016 is a leap year.
2020 is a leap year.
2024 is a leap year.
2048 is a leap year.
2032 is a leap year.

*/

 

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Answer 2

#include <iostream>
#include <array>

bool isLeapYear(int year) {
    return !(year & (year % 100 ? 3 : 15));
}

int main() {
    std::array<int, 15> years = {
        2000, 2400, 1800, 1900, 2100, 2200, 2300, 2500,
        2008, 2012, 2016, 2020, 2024, 2048, 2032
    };

    for (int year : years) {
        if (isLeapYear(year))
            std::cout << year << " is a leap year.\n";
        else
            std::cout << year << " is not a leap year.\n";
    }
}



/*
run:

2000 is a leap year.
2400 is a leap year.
1800 is not a leap year.
1900 is not a leap year.
2100 is not a leap year.
2200 is not a leap year.
2300 is not a leap year.
2500 is not a leap year.
2008 is a leap year.
2012 is a leap year.
2016 is a leap year.
2020 is a leap year.
2024 is a leap year.
2048 is a leap year.
2032 is a leap year.

*/

 

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Answer 3

#include <iostream>
#include <array>

bool isLeapYear(int year) {
    if (year % 400 == 0)
        return true;
    else if (year % 100 == 0)
             return false;
    else if (year % 4 == 0)
             return true;
      
    return false;
}

int main() {
    std::array<int, 15> years = {
        2000, 2400, 1800, 1900, 2100, 2200, 2300, 2500,
        2008, 2012, 2016, 2020, 2024, 2048, 2032
    };

    for (int y : years) {
        if (isLeapYear(y))
            std::cout << y << " is a leap year\n";
        else
            std::cout << y << " is NOT a leap year\n";
    }
}



/*
run:

2000 is a leap year
2400 is a leap year
1800 is NOT a leap year
1900 is NOT a leap year
2100 is NOT a leap year
2200 is NOT a leap year
2300 is NOT a leap year
2500 is NOT a leap year
2008 is a leap year
2012 is a leap year
2016 is a leap year
2020 is a leap year
2024 is a leap year
2048 is a leap year
2032 is a leap year

*/

 

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