Golang : How to determine if a year is leap year?



Tags : golang date leap-year

A leap year is a year with 366 days instead of 365 days. The algorithm to calculate if a year is a leap can be summarized like :

 if year is divisible by 400 then
 is_leap_year
 else if year is divisible by 100 then
 not_leap_year
 else if year is divisible by 4 then
 is_leap_year
 else
 not_leap_year

However, we are not going to implement this algorithm, but rather get the number of days in a given year and determine if that particular year is a leap year or not.

Here you go!

 package main

 import (
 "fmt"
 "time"
 )

 func IsLeapYear(y int) bool {

 //Thirty days hath September,
 //April, June and November;
 //February has twenty eight alone
 //All the rest have thirty-one
 //Except in Leap Year, that's the time
 //When February's Days are twenty-nine

 // convert int to Time - use the last day of the year, which is 31st December
 year := time.Date(y, time.December, 31, 0, 0, 0, 0, time.Local)
 days := year.YearDay()

 if days > 365 {
 return true
 } else {
 return false
 }
 }

 func main() {

 fmt.Println("1998 is leap year? ", IsLeapYear(1998))
 fmt.Println("1997 is leap year? ", IsLeapYear(1997))
 fmt.Println("1996 is leap year? ", IsLeapYear(1996))
 fmt.Println("1995 is leap year? ", IsLeapYear(1995))
 }

Output :

1998 is leap year? false

1997 is leap year? false

1996 is leap year? true

1995 is leap year? false

References :

http://golang.org/pkg/time/#Time.YearDay

http://en.wikipedia.org/wiki/Leap_year



Tags : golang date leap-year

By Adam Ng

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