编程题：用函数实现，用户输入年月日，来计算出该日期为当年第几天？

#include<stdio.h>

/*函数is_leap_year（）的返回值是判断该年是否闰年*/

int is_leap_year(int year)

{ int leap;

  if(year%4==0&&year%100!=0||year%400==0) leap=1;

  else leap=0;

  return leap;

}

/*函数len_of_month()的返回值为某年year的某月month的天数*/

int len_of_month(int year,int month)

{ int month_days;

  if(month==2)

  if(is_leap_year(year)) month_days=29;

  else month_days=28;

   else if(month==4||month==6||month==9||month==11)  month_days=30;

        else month_days=31;

return month_days;

}

/*函数len_of_days()的返回值为该日期date是该年year的第几天*/

int len_of_days(int year,int month,int date)

{  int total_days,n;

   for(n=1,total_days=0;n<month;n++)

        total_days+=len_of_month(year,n);

   total_days+=date;

   return total_days;

}

void main()

{ int year,month,date,days,n;

  printf("please input year,month,date:");

  scanf("%d,%d,%d",&year,&month,&date);

  days=len_of_days(year,month,date);

  printf("%d/%d/%d is the %d in %d\n",year,month,date,days,year);

}

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