定义一个结构体变量（包括年、月、日），计算该日在本年中为第几天？（注意考虑闰年问题），要求写一个函数days，实现上面的计算。由主函数将年月日传递给days函数，计算后将日子传递回主函数输出-Define a structure variable (including the year, month, day), calculated on that day in the middle of this year for the first few days? (Note that the lea