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- /* 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) << ".\n"
- << "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-commutative, and may create problems for applications.\n"
- << "Consider: \n"
- << "Jan 30, 2004 + (1 month) + (1 month) != Jan 30, 2004 + (2 months)\n"
- << "Why not? Because Jan 30, 2004 + 1 month is Feb 29 + 1 month is Mar 31st.\n"
- << "while Jan 30, 2004 + 2 months is Mar 30th.\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";
-
- date d6(2004, Jan, 30);
- date d7 = d6 + months(1) + months(1);
- date d8 = d6 + months(2);
- std::cout << "2004-01-30 + (1 month) + (1 month) is: " << to_simple_string(d7) << ".\n"
- << "2004-01-30 + (2 months) is: " << to_simple_string(d8)
- << std::endl;
- 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)
- */
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