Let’s say that you have two dates:

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"2019-01-29"
"2019-06-30"

How would you create a function that would return the number of days between these two dates?

Introducing the Datetime Package

Python comes with a built-in library called datetime.

We start by importing the date module.

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from datetime import date

With this date module, we have access to an object format of the date type.

Writing our Function

Next, we should write our function that takes in two dates and returns the number of days between them.

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from datetime import date

# date1 = str
# date2 = str
# return = int
def daysBetweenDates(date1, date2) -> int:

    # create list of of dates
    date1 = date1.split("-")
    date2 = date2.split("-")

    # create date objects from our list indices        
    date1_d = date(int(date1[0]), int(date1[1]), int(date1[2]))
    date2_d = date(int(date2[0]), int(date2[1]), int(date2[2]))
    
    # get the amount of days between our two dates
    days = (date1_d - date2_d).days
    
    # return an absolute (positive) integer of the days
    return abs(int(days)

We created lists of our dates to be able to use them in the `date` function:

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print( "2019-06-30".split("-") )

['2019', '06', '30']

As the date function takes in integer values, we can now use the appropriate index locations of our date lists.

Testing our Function

Let’s test our function out:

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print( daysBetweenDates("2019-01-29", "2019-06-30") )

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