R Program to Check Leap Year

A leap year is a calendar year in which an additional day is added to February month. In a leap year, the number of days in February month and the year are 29 and 366 respectively. A year that is not a leap year is called a common year. A year is said to be a leap year if:

• it is divisible by 4.
• it is divisible by 4 but not divisible by 100.
• it is divisible by 4, 100 and 400.

Method 1: Using conditional statements

In the example below, conditional statements are used to identify a leap year.

year <- 2019
if (year %% 400 == 0) {
  sprintf("%d is a leap year.", year)
} else if (year %% 100 == 0) {
  sprintf("%d is a leap year.", year)
} else if (year %% 4 == 0) {
  sprintf("%d is a leap year.", year)
} else {
  sprintf("%d is not a leap year.", year)
}

The above code will give the following output:

[1] "2019 is not a leap year."

Method 2: Using function

In the example below, a function called leapyear() is created which takes year as argument and prints whether the passed year is a leap year or not.

leapyear <- function(year) {
  if (year %% 400 == 0) {
    sprintf("%d is a leap year.", year)
  } else if (year %% 100 == 0) {
    sprintf("%d is a leap year.", year)
  } else if (year %% 4 == 0) {
    sprintf("%d is a leap year.", year)
  } else {
    sprintf("%d is not a leap year.", year)
  }
}

leapyear(2019)

The above code will give the following output:

[1] "2019 is not a leap year."