C# 计算某个日期所在的周是当年的第几周

引用：

using System.Globalization;

 

函数：

public static int WeekOfYear(DateTime dt, CultureInfo ci)
        {
            return ci.Calendar.GetWeekOfYear(dt, ci.DateTimeFormat.CalendarWeekRule, ci.DateTimeFormat.FirstDayOfWeek);
        }

调用：

int a=WeekOfYear(this.dateTimePicker1.Value, new CultureInfo("zh-CN"));