#include<stdio.h>
int year,month,day,leap,sum=0;
int main()
{
    int leaper(int years);
    int summer(int date);
    printf("输入年 月 日：\n");
    scanf("%d%d%d",&year,&month,&day);
    int leaper(int years);
    int summer(int date);
    printf("该日是%d年的第%d天\n",year,sum);
    return 0;
}
int leaper(int years)
{
    if(year%4==0)
    {
        if(year%100==0)
        {
            if(year%400==0)
                leap=1;
            else
                leap=0;
        }
            else
                leap=1;
    }
        else
                leap=0;
        return(0);
}
int summer(int date)
{
    int leaper(int years);
    int sum=0;
    int b[12]={31,28,31,30,31,30,31,31,30,31,30,31};
    if(month=0)
        sum=day;
    else if(year=leap){
            for(month=1;month<12;month++)
            sum=sum+b[month-1]+day+1;
        }
        else
            sum=sum+b[month];
        return(sum);
}

我的闰年算法没错呀，能执行，主函数中printf输出有误。谢谢。

能输出呀

好吧 谢谢