C语言给出年月日，判断该日是该年的第几天

以下是C语言实现给出年月日，判断该日是该年的第几天的代码：

#include <stdio.h>

int main()
{
    int year, month, day, sum = 0, leap;
    printf("请输入年、月、日，格式为：年,月,日\n");
    scanf("%d,d,%d", &year, &month, &day);
    switch (month) // 计算月份之前的天数
    {
    case 1:
        sum = 0;
        break;
    case 2:
        sum = 31;
        break;
    case 3:
        sum = 59;
        break;
    case 4:
        sum = 90;
        break;
    case 5:
        sum = 120;
        break;
    case 6:
        sum = 151;
        break;
    case 7:
        sum = 181;
        break;
    case 8:
        sum = 212;
        break;
    case 9:
        sum = 243;
        break;
    case 10:
        sum = 273;
        break;
    case 11:
        sum = 304;
        break;
    case 12:
        sum = 334;
        break;
    default:
        printf("输入错误！\n");
        break;
    }
    sum += day; // 加上当月的天数
    if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) // 判断是否为闰年
        leap = 1;
    else
        leap = 0;
    if (leap == 1 && month > 2) // 如果是闰年且月份大于2月，总天数加1
        sum++;
    printf("该日是该年的第%d天\n", sum);
    return 0;
}