Why are fractional data types generally not implemented? [closed]

Question

I have been working with C/C++ for quite a few years. I have also worked with few other programming languages but none have built-in fractional datatypes. Here I am not talking about the regular decimal datatypes like float. I am referring to regular mathematical fractions having the following form:

Nr/Dr where Dr≠0

What are the challenges that are faced by the developers in implementing such datatypes?

Answer 1

Builtin data types tend to be those that are widely useful, and map more or less efficiently to the underlying architecture. This is no hard and fast rule, but it’s a pretty good rule of thumb.

Fractional data types are neither: they would be widely useful, but limited-precision floating-point types are good enough for 99.9% ^{(or 999/1000, if you prefer)} of applications, can be implemented much more efficiently due to hardware support, and have far fewer theoretical and practical limitations because they represent a more general domain of numbers (i.e. not just operations on rational numbers).

There are specific applications where floating point data types don’t cut it, and where arbitrary-precision rational numbers are needed. For those cases, special libraries exist. Cluttering standard libraries with these types would be a waste of effort.

So, essentially, the answer is the same as for any other specialised data type that isn’t widely implemented as a built-in type.