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 leap to consider the issue), asked to write a function of days, to achieve the above calculations. By the main function will be passed to the days date function to calculate the days will pass back to the main function of the output