CODEWITHSUNDEEP
pythondatetime
Emily Kelt
Emily Kelt

Reputation: 9

How to subtract from a value if the day is a certain day

I'm new to python, and I'm trying to make a pocket money/ saving calculator, where it assumes you get money every week and a set amount of money on birthdays/christmas and tell you how long it will take to reach the amount you are trying to save up for. It works well in counting the weeks it would take to reach the goal, but it seems to ignore the special dates. Is there a way I can change the code so that it would take them into account?

import datetime as dt
import math as mt

current_balance = float(input("What is your current balance?: £"))
pocket_money = float(input("How much pocket money do you get per week?: £"))
goal = float(input("How much money do you need?: £"))

today = dt.date.today()


if goal <= current_balance:
    print(f"You already have enough money and you will have £{current_balance-goal} left.")
else:
    money_needed = goal - current_balance

    datetest = today
    d = dt.timedelta(days=1)
    counter = 0 
    birthday = dt.datetime(datetest.year, 5, 16)
    christmas = dt.datetime(datetest.year, 12, 25)

    while money_needed > 0:

        if datetest.weekday() == 0:
            money_needed = money_needed - 5
            counter += 1
            datetest += d
        elif datetest == birthday or datetest == christmas:    #<-- This bit seems to do nothing
            money_needed = money_needed - 200
            if  datetest.weekday() == 0:
                counter += 1
            datetest += d
        else:
            datetest += d

print(counter)

e.g. if the first three inputs were 10, 5, and 500, it would return 98, which is the number of weeks it would take if the birthday/christmas was ignored.

Upvotes: 0

Views: 61

Answers (1)

Ofer Sadan
Ofer Sadan

Reputation: 11912

A few issues:

  1. You're not using pocket_money at all in your script, you're just using money_needed = money_needed - 5 each week, so the calculation is messed up even before trying to consider christmas and birthdays.
  2. datetest += d runs inside every possible date, so no need to repeat that 3 times in the loop
  3. There's also no need to repeat counter += 1 as it always happens on the same weekday regardless of holidays

Lastly, the most important issue: If you print out today you will see it's equal to 2021-09-06 but if you print out your birthday for example, you will see it is equal to 2021-05-16 00:00:00. Notice a different in their format? They can never be equal! One is a datetime object and the other just a date object. To fix that, compare the date directly (day and month) or just use date instead of datetime when defining them

To implement all of that:

import datetime as dt
import math as mt

current_balance = float(input("What is your current balance?: £"))
pocket_money = float(input("How much pocket money do you get per week?: £"))
goal = float(input("How much money do you need?: £"))

today = dt.date.today()

if goal <= current_balance:
    print(f"You already have enough money and you will have £{current_balance-goal} left.")
else:
    money_needed = goal - current_balance

    datetest = today
    d = dt.timedelta(days=1)
    counter = 0 
    birthday = dt.date(datetest.year, 5, 16)
    christmas = dt.date(datetest.year, 12, 25)

    while money_needed > 0:
        datetest += d
        if datetest.weekday() == 0:
            money_needed = money_needed - pocket_money
            counter += 1

        if datetest == birthday or datetest == christmas:
            money_needed = money_needed - 200


print(counter)

Upvotes: 1

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