What is the best data type for storing your birthday?

Answer 1

The choice of data type for storage the date of birth of a human depends on how the algorithm will use that data.

For algorithms which store this data merely for display purposes, storing the date of birth as a text might be suitable.

In many cases, however, operations such as comparison for equality or greater-than or less-than relationships are required, for example in order to support sorting and searching algorithms. This typically leads to the implementation of a numeric data format, often using a scalar such as a 16-bit or 32-bit unsigned integer. Such a format could, for example, encode the date of birth as the number of dates since January 1st, 1970.

This method limits the maximum age of people on record (1-1-1970) and has a limited lifetime, as it may only support 216 or 232 days in total. While these limitations may be perfectly acceptable in many applications, a more general approach might use a data structure containing distinct numeric fields for the day, month and year, possibly including other details such as the calendar system, or an uncertainty factor (useful when estimating the age of archaeological finds, for example).

Many databases and some programming languages provide built-in support for data types such as Date and Time, which might be suitable for a given application, subject to the application's requirements and limitations imposed by those data types.