| /* Simple program that uses the gregorian calendar to progress by exactly |
| * one month, regardless of how many days are in that month. |
| * |
| * This method can be used as an alternative to iterators |
| */ |
| |
| #include "boost/date_time/gregorian/gregorian.hpp" |
| #include <iostream> |
| |
| int |
| main() |
| { |
| |
| using namespace boost::gregorian; |
| |
| date d = day_clock::local_day(); |
| date d2 = d + months(1); |
| date d3 = d - months(1); |
| std::cout << "Today is: " << to_simple_string(d) << ".\n" |
| << "One month from today will be: " << to_simple_string(d2) |
| << "One month ago was: " << to_simple_string(d3) |
| << std::endl; |
| std::cout << "******** Warning read this ***********************\n"; |
| std::cout << "Be aware that adding a month is not exactly like regular numeric math.\n" |
| << "Addition/Subtraction of months will 'snap to the end' of a month that\n" |
| << "is shorter than the current month. For example consider " |
| << "Jan 31, 2004 + (1 month)\n"; |
| date d4(2004, Jan, 31); |
| date d5 = d4 + months(1); |
| std::cout << "Result is: " << to_simple_string(d5) |
| << std::endl; |
| |
| std::cout << "\nSo what does this mean? It means the result of adding months is order\n" |
| << "dependent, non-communitive, and may create problems for applications.\n" |
| << "Consider: \n" |
| << "Jan 30, 2004 + (1 month) + (1 month) != Jan 29, 2004 + (2 months)\n" |
| << "Why not? Because Jan 30, 2004 + 1 month is Feb 29 + 1 month is Mar 29th.\n" |
| << "while Jan 30, 2004 + 2 months is Mar 29th.\n" |
| << "All of this clears up as long as all the starting dates before the 28th of\n" |
| << "the month -- then all the behavior follows classical mathematical rules.\n"; |
| |
| |
| return 0; |
| } |
| |
| /* Copyright 2001-2005: CrystalClear Software, Inc |
| * http://www.crystalclearsoftware.com |
| * |
| * Subject to the Boost Software License, Version 1.0. |
| * (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
| */ |
| |
