proper/best type for storing latitude and longitude

Question

In a system level programming language like C, C++ or D, what is the best type/encoding for storing latitude and longitude?

The options I see are:

• IEEE

Answer 1

A Decimal representation with precision of 8 should be more than enough according to this wikipedia article on Decimal Degrees.

0 decimal places, 1.0 = 111 km
...
7 decimal places, 0.0000001 = 1.11 cm
8 decimal places, 0.00000001 = 1.11 mm