In file included from /usr/include/c++/7/cassert:44:0,
                 from main.cpp:15:
main.cpp: In function 'int main()':
main.cpp:22:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "19.01.1997");
                   ^
main.cpp:27:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "01.10.0100");
                   ^
main.cpp:32:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "01.01.0001");
                   ^
main.cpp:37:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "22.10.2000");
                   ^
main.cpp:42:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "09.01.0400");
                   ^
main.cpp:47:19: error: 'class Date' has no member named 'ToString'
         assert(dt.ToString() == "08.07.1996");
                   ^
main.cpp:51:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(0).ToString() == "01.01.2000");
                   ^
main.cpp:52:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(10).ToString() == "11.01.2000");
                   ^
main.cpp:53:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(30).ToString() == "31.01.2000");
                   ^
main.cpp:54:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(31).ToString() == "01.02.2000");
                   ^
main.cpp:55:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(60).ToString() == "01.03.2000");
                   ^
main.cpp:56:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(366).ToString() == "01.01.2001");
                   ^
main.cpp:60:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(0).ToString() == "01.01.2001");
                   ^
main.cpp:61:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(10).ToString() == "11.01.2001");
                   ^
main.cpp:62:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(30).ToString() == "31.01.2001");
                   ^
main.cpp:63:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(31).ToString() == "01.02.2001");
                   ^
main.cpp:64:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(59).ToString() == "01.03.2001");
                   ^
main.cpp:65:19: error: 'class Date' has no member named 'DaysLater'
         assert(dt.DaysLater(365).ToString() == "01.01.2002");
                   ^
main.cpp:69:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2000, 1, 1}) == 0);
                   ^
main.cpp:70:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2000, 1, 11}) == 10);
                   ^
main.cpp:71:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2000, 1, 31}) == 30);
                   ^
main.cpp:72:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2000, 2, 1}) == 31);
                   ^
main.cpp:73:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2000, 3, 1}) == 60);
                   ^
main.cpp:74:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 1, 1}) == 366);
                   ^
main.cpp:78:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 1, 1}) == 0);
                   ^
main.cpp:79:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 1, 11}) == 10);
                   ^
main.cpp:80:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 1, 31}) == 30);
                   ^
main.cpp:81:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 2, 1}) == 31);
                   ^
main.cpp:82:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2001, 3, 1}) == 59);
                   ^
main.cpp:83:19: error: 'class Date' has no member named 'DaysLeft'
         assert(dt.DaysLeft(Date{2002, 1, 1}) == 365);
                   ^