这天是这年的第几天

#include<stdio.h>
int day_of_year(int year,int mouth,int day);
int main(){
int year,mouth,day,date;
printf("输入年月日：");
scanf("%d%d%d",&year,&mouth,&day);
date=day_of_year(year,mouth,day);
printf("这天是这年的第%d天\n",date);
return 0;
}
int day_of_year(int year,int mouth,int day){
int k,leap;
int tab[2][13]={
{0,31,28,31,30,31,30,31,31,30,31,30,31},
{0,31,29,31,30,31,30,31,31,30,31,30,31}
};

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

for(k=1;k<mouth;k++){
day=day+tab[leap][k];
}

return day;
}