C语言实现蔡勒公式，用于给定年月日计算出当前是周几

int getDayOfWeek(int year, int month, int day)
{
    int c, y, week;
    if (month == 1 || month == 2) //判断month是否为1或2　
    {
        year--;
        month += 12;
    }

    c = year / 100;
    y = year - c * 100;
    week = (c / 4) - 2 * c + (y + y / 4) + (13 * (month + 1) / 5) + day - 1;

    while (week < 0)
    {
        week += 7;
    }
    week %= 7;
    return week;
}

void main(void)
{
    int year = 0, month = 0, day = 0, week = 0;
    while (1)
    {
        scanf("%d%d%d", &year, &month, &day);
        printf("current input data:rn20%d-%d-%drn", year, month, day);
        week = getDayOfWeek(year, month, day);
        printf("week: %d", week);
    }
}

使用如下图：