In this answer I proposed that marihikari use the standard functionality of mktime
rather than trying to implement his own Gregorian calendar system.
I wrote this function to demonstrate how mktime
could be used to accomplish this:
bool leap_year(int year) {
tm bar = { 0, 0, 0, 29, 1, year - 1900 };
mktime(&bar);
return bar.tm_mday == 29 && bar.tm_mon == 1 && bar.tm_year == year - 1900;
}
Testing this with:
cout << "2000: " << leap_year(2000) << "\n2001: " << leap_year(2001) << "\n2004: " << leap_year(2004) << "\n1900: " << leap_year(1900) << "\n2100: " << leap_year(2100) << endl;
Yielded the correct result in Clang 3.7.0:
2000: 1
2001: 0
2004: 1
1900: 0
2100: 0
But an incorrect result in gcc 5.1.0:
2000: 1
2001: 0
2004: 1
1900: 1
2100: 1
And an incorrect result in Visual Studio 2015:
2000: 1
2001: 0
2004: 1
1900: 1
2100: 0
I assume this is a bug in gcc 5.1.0 and Visual Studio 2015?