问题描述

C#求今天是一年中的第几周怎么算？

C#求今天是一年中的第几周怎么算？

解决方案

 private   int   WeekOfYear(string   date)
{
DateTime   curDay   =   Convert.ToDateTime(date); 

int   firstdayofweek   =   Convert.ToInt32(Convert.ToDateTime(curDay.Year.ToString()   +   "- "   +   "1-1 ").DayOfWeek); 

int   days   =   curDay.DayOfYear;
int   daysOutOneWeek   =   days   -   (7   -   firstdayofweek); 

if   (daysOutOneWeek   <=   0)
{
return   1;
}
else
{
int   weeks   =   daysOutOneWeek   /   7;
if   (daysOutOneWeek   %   7   !=   0)
weeks   ++; 

return   weeks   +   1;
}
}

http://blog.csdn.net/letian_fly/article/details/2739618

解决方案二：

方法一：

private int WeekOfYear(string date)
{
DateTime curDay = Convert.ToDateTime(date);

int firstdayofweek = Convert.ToInt32(Convert.ToDateTime(curDay.Year.ToString() + "- " + "1-1 ").DayOfWeek);

int days = curDay.DayOfYear;
int daysOutOneWeek = days - (7 - firstdayofweek);

if (daysOutOneWeek <= 0)
{
return 1;
}
else
{
int weeks = daysOutOneWeek / 7;
if (daysOutOneWeek % 7 != 0)
weeks ++;

return weeks + 1;
}
}

方法二：

System.Globalization.GregorianCalendar gc = new System.Globalization.GregorianCalendar();
int weekOfYear = gc.GetWeekOfYear(DateTime.Now, System.Globalization.CalendarWeekRule.FirstDay, DayOfWeek.Monday);

解决方案三：

这个算法百度一下 网上太多了，不过大多都是C语言版本的，修改成C#应该挺简单的

解决方案四：

dt.DayOfYear/7