Calculating age in python

Question

I am attempting to create a code where the user is asked for their date of birth and today's date in order to determine their age. What I have written so far is:

print("Your date of birth (mm dd yyyy)")
Date_of_birth = input("--->")

print("Today's date: (mm dd yyyy)")
Todays_date = input("--->")


from datetime import date
def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))

age = calculate_age(Date_of_birth)

However it is not running like I would hope. Could someone explain to me what I am doing wrong?

Solution 1

So close!

You need to convert the string into a datetime object before you can do calculations on it - see datetime.datetime.strptime().

For your date input, you need to do:

datetime.strptime(input_text, "%d %m %Y")

#!/usr/bin/env python3

from datetime import datetime, date

print("Your date of birth (dd mm yyyy)")
date_of_birth = datetime.strptime(input("--->"), "%d %m %Y")

def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))

age = calculate_age(date_of_birth)

print(age)

---

PS: I urge you to use a sensible order of input - dd mm yyyy or the ISO standard yyyy mm dd

Solution 2

This should work :)

from datetime import date

def ask_for_date(name):
    data = raw_input('Enter ' + name + ' (yyyy mm dd): ').split(' ')
    try:
        return date(int(data[0]), int(data[1]), int(data[2]))
    except Exception as e:
        print(e)
        print('Invalid input. Follow the given format')
        ask_for_date(name)


def calculate_age():
    born = ask_for_date('your date of birth')
    today = date.today()
    extra_year = 1 if ((today.month, today.day) < (born.month, born.day)) else 0
    return today.year - born.year - extra_year

print(calculate_age())

Solution 3

You can also use date time library in this manner. This calculates the age in years and removes the logical error that returns wrong age due to the month and day properties

Like a person born on 31 July 1999 is a 17 year old till 30 July 2017

So here's the code :

import datetime

#asking the user to input their birthdate
birthDate = input("Enter your birth date (dd/mm/yyyy)\n>>> ")
birthDate = datetime.datetime.strptime(birthDate, "%d/%m/%Y").date()
print("Your birthday is on "+ birthDate.strftime("%d") + " of " + birthDate.strftime("%B, %Y"))

currentDate = datetime.datetime.today().date()

#some calculations here 
age = currentDate.year - birthDate.year
monthVeri = currentDate.month - birthDate.month
dateVeri = currentDate.day - birthDate.day

#Type conversion here
age = int(age)
monthVeri = int(monthVeri)
dateVeri = int(dateVeri)

# some decisions
if monthVeri < 0 :
    age = age-1
elif dateVeri < 0 and monthVeri == 0:
    age = age-1


#lets print the age now
print("Your age is {0:d}".format(age))