wxWidgets provides a set of powerful classes to work with dates and times. Some of the supported features of wxDateTime class are:

Wide range The range of supported dates goes from about 4714 B.C. to some 480 million years in the future.
Precision Not using floating point calculations anywhere ensures that the date calculations don't suffer from rounding errors.
Many features Not only all usual calculations with dates are supported, but also more exotic week and year day calculations, work day testing, standard astronomical functions, conversion to and from strings in either strict or free format.
Efficiency Objects of wxDateTime are small (8 bytes) and working with them is fast

ymasuda 平成17年11月19日