为什么下面的程序输出错误

[qq_2781974619]

//问题八：输入年、月、日，在屏幕上输出此日期是该年的第几天
#include<stdio.h>
int main()
{
int year,month,day,what_day;
// int a[130],b[130];
int a[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
int b[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
scanf("%d,%d,%d",year,month,day);
if(year%4==0)
{
for(;month>0;month--)
what_day+=a[month];
printf("\n%d",what_day);
}
else
{
for(;month>0;month--)
what_day+=b[month];
printf("\n%d",what_day);
}
what_day+=day;
// printf("\n第%d天",what_day);
return 0;
}

[FoolCarpe]

	scanf("%d,%d,%d", &year, &month, &day);  //添加 &

[自信男孩]

#include<stdio.h>

int main()
{
    int year,month,day,what_day = 0;
    //   int a[130],b[130];
    int a[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
    int b[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    scanf("%d,%d,%d", &year, &month, &day);
    if(year%4==0 || (year % 4 == 0 && year % 100 != 0))
    {
        for(;month>0;month--)
            what_day+=a[month];
        printf("\n%d",what_day);
    }
    else
    {
        for(;month>0;month--)
            what_day+=b[month];
        printf("\n%d",what_day);
    }
    what_day+=day;
    //  printf("\n第%d天",what_day);
    return 0;
}

三个问题： 1. 输入格式不正确，年月日变量缺少& 2. 闰年判断不对； 3. what_day没有初始化；

[自信男孩]

当然还有多算一个月，a的下标应该从month-1开始算

#include<stdio.h>

int main()
{
    int year,month,day,what_day = 0;
    //   int a[130],b[130];
    int a[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
    int b[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    scanf("%d,%d,%d", &year, &month, &day);
    if(year%400 ==0 || (year % 4 == 0 && year % 100 != 0))
    {
        for(month = month-1;month>0;month--)
            what_day+=a[month];
        printf("\n%d",what_day);
    }
    else
    {
        for(month = month-1;month>0;month--)
            what_day+=b[month];
        printf("\n%d",what_day);
    }
    what_day+=day;
    //  printf("\n第%d天",what_day);
    return 0;
}