What is the expected result if dob is a leap day?

Ruby: 2200-05-16 is considered not yet born, but it is before 2200-06-15 and so should've been born.

C++ has an error in tests:

In file included from main.cpp:7:
./tests.cpp:133:7: error: use of undeclared identifier 'leapYear'
  if (leapYear(year) && month == 2 && year != 0) { return 29; }
      ^
1 error generated.

Also sample tests are wrong. They assume a current date of 2200-01-01.

Trying C++ and having a concern: if I was born in "2002-01-01" and the date (const TIME) is "2200-06-15", then my next birthday should be on "2201-01-01" ???

Use the real amount of days for every month, as well as considering leap years.

Why do people think that performing calculations on abstract "dynamic" values is a good idea? Different months and years have different amounts of days - could you explain how am I supposed to tell the number of months and years since/until some date? What would be the result for 2199-10-03 (which is exactly 90 days before 2200-01-01)? "1 month and 60 days"? "1 month and 59 days"? "2 months and 29 days"? Something else?