Kotlin Program to Check Leap Year

In this program, you’ll learn to check if the given year is a leap year or not in Kotlin. This is checked using a if else statement and a when statement.

A leap year is exactly divisible by 4 except for century years (years ending with 00). The century year is a leap year only if it is perfectly divisible by 400.

Example 1: Kotlin Program to Check a Leap Year using if else statement

  1. fun main(args: Array<String>) {
  3. val year = 1900
  4. var leap = false
  6. if (year % 4 == 0) {
  7. if (year % 100 == 0) {
  8. // year is divisible by 400, hence the year is a leap year
  9. leap = year % 400 == 0
  10. } else
  11. leap = true
  12. } else
  13. leap = false
  15. println(if (leap) "$year is a leap year." else "$year is not a leap year.")
  16. }

When you run the program, the output will be:

1900 is not a leap year.

In the above program, given year 1900 is stored in the variable year.

  • Since 1900 is divisble by 4 and is also a century year (ending with 00), it has be divisble by 400 for a leap year. Since it’s not divisible by 400, 1900 is not a leap year.
  • But, if we change the year to 2000, it is divisible by 4, is a century year and is also divisible by 400. So, 2000 is a leap year.
  • Likewise, If we change the year to 2012, it is divisible by 4 and is not a century year, so 2012 a leap year. We don’t need to check if 2012 is divisible by 400 or not.

Example 2: Kotlin Program to Check Leap Year using when expression

  1. fun main(args: Array<String>) {
  3. val year = 2012
  4. var leap = false
  6. leap = when {
  7. year % 4 == 0 -> {
  8. when {
  9. year % 100 == 0 -> year % 400 == 0
  10. else -> true
  11. }
  12. }
  13. else -> false
  14. }
  16. println(if (leap) "$year is a leap year." else "$year is not a leap year.")
  17. }

When run the program, the output will be:

2012 is a leap year.

In the above program, instead of using an if else statement, we have used a when expression.

The when expression works as:

  • When year is divisible by 4
    • Another when expression is entered which checks if year is divisible by 100
      • If yes, it again checks if year is divisble by 400 or not, and returns true or false
    • If not divisble by 100, year is not a century year (ending with 00) and returns true
  • If year is not divisible by 4, it returns false

Based on the value of leap, it prints the output using an inline if else.