Golang : Find age or leap age from date of birth example

Alright, here is a simple tutorial on how to calculate a person's age by a given date of birth string. The code below will take a date of birth string input and spits out the equivalent age in years and if the date of birth is on 29th February, it will give the leap age as well.

Here you go!

 package main

 import (
 "fmt"
 "strconv"
 "time"
 )

 func monthToInt(month string) int {
 switch month {
 case "January":
 return 1
 case "February":
 return 2
 case "March":
 return 3
 case "April":
 return 4
 case "May":
 return 5
 case "June":
 return 6
 case "July":
 return 7
 case "August":
 return 8
 case "September":
 return 9
 case "October":
 return 10
 case "November":
 return 11
 case "December":
 return 12
 default:
 panic("Unrecognized month")
 }
 }

 func ageFromDateOfBirth(dob string) (int, int) {
 layOut := "02/01/2006"  // dd/mm/yyyy
 dobTime, err := time.Parse(layOut, dob)

 if err != nil {
 panic(err)
 }

 var ageYear, leapAge int
 ageYear = time.Now().Year() - dobTime.Year()

 // the trick here is to combine the day and month into an integer of string type

 dobDayMonth, _ := strconv.Atoi(strconv.Itoa(dobTime.Day()) + strconv.Itoa(monthToInt(dobTime.Month().String())))
 nowDayMonth, _ := strconv.Atoi(strconv.Itoa(time.Now().Day()) + strconv.Itoa(monthToInt(time.Now().Month().String())))

 // if the DOB's day + month is larger than today's day + month
 // then the age is still younger by 1 year

 if dobDayMonth > nowDayMonth {
 ageYear = ageYear - 1
 }

 if dobDayMonth == 292 { // dob on 29th Feb - leap year
 leapAge = ageYear / 4
 } else {
 leapAge = 0
 }

 return ageYear, leapAge
 }

 func main() {

 // dd/mm/yyyy format
 dob := "28/10/1978"
 age, _ := ageFromDateOfBirth(dob)
 fmt.Println(dob, " age is : ", age)

 dob1 := "01/10/1978"
 age1, _ := ageFromDateOfBirth(dob1)
 fmt.Println(dob1, " age is : ", age1)

 dob2 := "02/05/1978"
 age2, _ := ageFromDateOfBirth(dob2)
 fmt.Println(dob2, " age is : ", age2)

 dob3 := "03/05/1978"
 age3, _ := ageFromDateOfBirth(dob3)
 fmt.Println(dob3, " age is : ", age3)

 // February 29, also known as leap day or leap year day,
 // is a date added to most years that are divisible by 4,
 // such as 2008, 2012, 2016, 2020, and 2024.

 dob4 := "29/02/2008" // leap year age test
 age4, leap := ageFromDateOfBirth(dob4)
 fmt.Println(dob4, " age is : ", age4)
 fmt.Println(dob4, " date of birth is 29th Feb and the leap age is : ", leap)

 dob5 := "29/02/1936" // leap year age test
 age5, leap1 := ageFromDateOfBirth(dob5)
 fmt.Println(dob5, " age is : ", age5)
 fmt.Println(dob5, " date of birth is 29th Feb and the leap age is : ", leap1)
 }

Sample output:

$ date

Tue May 2 13:51:40 MYT 2017

$ ./agedob

28/10/1978 age is : 38

01/10/1978 age is : 38

02/05/1978 age is : 39

03/05/1978 age is : 38

29/02/2008 age is : 8

29/02/2008 date of birth is 29th Feb and the leap age is : 2

29/02/1936 age is : 80

29/02/1936 date of birth is 29th Feb and the leap age is : 20

Happy coding!

References:

https://en.wikipedia.org/wiki/February_29

https://www.socketloop.com/tutorials/golang-convert-date-string-to-variants-of-time-time-type-examples