c语言作业编写程序输入某年某月某天，求这是这一年的第几天

#include
 
int main()
{
    int sum;
    int i,t,c;
    int month[12]={31,28,31,30,31,30,31,31,30,31,30,31};
    int year,mon,day;
    printf("Please enter the times you want to calculate(eg.2):");
    scanf("%d",&t);
    for(c=0;c    {
        sum=0;
        printf("\n");
        printf("Please enter the date(eg.2016/06/20):");
        scanf("%d/%d/%d",&year,&mon,&day);
 
        if( (year%400==0) || ((year%4==0)&&(year%100!=0)) )
            month[1]=29;
        for(i=0;i            sum=sum+month[i];
 
        sum=sum+day;
        printf("It's the %dth day in this year.\n",sum);
    }
    return 0;
}