DATESADDday

DATESADDday is a function described in some programming environments as a tool to add or subtract a number of days to a given date value, producing a new date as the result. It is not a universally standardized function and may appear as a user-defined routine or a misnamed alias for a more common date arithmetic function in a particular language or library. When encountered, its exact syntax and behavior depend on the host system, so readers should consult the specific documentation for the implementation in use.

Typically, a DATESADDday-like function would take two primary arguments: a date and an integer representing the number of days to add (negative values subtract days). The operation should handle calendar rules automatically, including month and year boundaries and leap years. In many implementations, inputs that are not valid dates or that cannot be interpreted as dates yield an error or a null result.

Examples illustrating the concept (illustrative, not universal syntax):

- Adding 1 day to 2023-01-31 yields 2023-02-01.

- Adding 1 day to 2020-02-28 yields 2020-02-29 (leap year).

Variations across platforms may differ in how time components and time zones are treated. Some environments treat the input as a date only (midnight time), while others preserve or adjust time information when adding days. Negative values are commonly supported to perform subtraction.

For broader compatibility, many languages offer equivalent functionality under different names, such as DATEADD with a day interval in SQL, or arithmetic with a days component in languages like Python (datetime + timedelta) or Excel (date arithmetic with serial date values). When implementing or using DATESADDday, it is prudent to verify the exact signature, return type, and edge-case behavior in the target system.