C Program to Check Leap Year - Nested if/else Logic

Check Whether a Year is a Leap Year

#include <stdio.h>

int main() {
    int year;

    printf("Enter a year: ");
    scanf("%d", &year);

    // Leap year if divisible by 400
    if (year % 400 == 0) {
        printf("%d is a leap year.\n", year);
    }
    // Not divisible by 400 but divisible by 100 means not a leap year
    else if (year % 100 == 0) {
        printf("%d is not a leap year.\n", year);
    }
    // Divisible by 4 means leap year
    else if (year % 4 == 0) {
        printf("%d is a leap year.\n", year);
    }
    // All other years are not leap years
    else {
        printf("%d is not a leap year.\n", year);
    }

    return 0;
}

Enter a year: 2000
2000 is a leap year.
        

Practice: Check Leap Year

The leap year rules ensure that our calendar stays aligned with the Earth’s orbit around the sun. A year divisible by 4 is typically a leap year, but century years (divisible by 100) must also be divisible by 400 to qualify. This nested if/else logic captures those rules in a clear way.