# UPDATE_DAY

Chandra Bergmann

#### The function UPDATE_DAY changes the day described by a Date or DateTime into another specified number.

This function takes two pieces of input: a Date or a DateTime, and a Number. It outputs the given Date or Datetime with the day value replaced by the given number.

### Declaration

UPDATE_DAY(datetime, new_day) -> new_datetime
UPDATE_DAY(date, new_day) -> new_date

### Parameters

datetime (type: DateTime)
Any DateTime.
date (type: Date)
Any date.
new_day (required, type: Number)
The new day; this is the number that will replace whatever value is currently associated with the day in the given Date or DateTime.

### Return Values

new_datetime (type: DateTime)
The DateTime that results from taking the given DateTime and replacing the day value with the given number.
new_date (type: Date)
The Date that results from taking the given Date and replacing the day value with the given number.

### Examples

example_date_and_time = { "date": {  "day": 1,  "month": 4,  "year": 2021 }, "time": {  "hour": 16,  "minute": 14,  "second": 38,  "millisecond": 0 }, "timeZone": "UTC"}

The following example takes the date described in example_date_and_time and replaces the given day value (1) with 16. Note that the only difference between the output of this example and example_date_and_time is the the value of the day. When given a DateTime as input, UPDATE_DAY returns a DateTime:

UPDATE_DAY(example_date_and_time, 16) = { "date": {  "day": 16,  "month": 4,  "year": 2021 }, "time": {  "hour": 16,  "minute": 14,  "second": 38,  "millisecond": 0 }, "timeZone": "UTC"}

The above example demonstrates how the UPDATE_DAY function behaves when given a DateTime as input. In order to further establish how the UPDATE_DAY function behaves when given a Date as input, assume the last example has access to the following Date value:

example_date = { "day": 1, "month": 4, "year": 2021}

The following example takes the Date described in example_date and replaces the given day value (1) with 16. Note that the only difference between the output of this example and example_date is the the value of the day. When given a Date as input, UPDATE_DAY outputs a Date:

UPDATE_DAY(example_date, 16) = { "day": 16, "month": 4, "year": 2021}