基于单文档界面， Visul C++日历的计算与显示， 可自定义年月日的颜色字体，

输入年月日，计算为该年的第几天！能识别不合理日期的输入，并能及时停止程序-Enter year, month date, calculated for the first few days in! Can identify the input date is unreasonable, and can stop the program in time

简单日期转化器，能自动识别闰年还是平年，对输入的年月日可以转换为一年的第几天，输入的天数可以自动转换成一年中的具体日期。-Simple date converter that can automatically identify a leap year or leap year, the input can be converted to year, month, day of the first few days, the number of days to enter Automatic