usingSystem; usingSystem.Collections.Generic; usingSystem.Linq; usingSystem.Text; namespaceWyfclass { Public classTools {/// <summary> ///get the first day of the week (first day of Sunday)/// </summary> /// <param name= "datetime" ></param> /// <returns></returns> Publicdatetime Getweekfirstdaysun (datetime datetime) {//Sunday for the first day intWeeknow =Convert.ToInt32 (DateTime. DayOfWeek); intDaydiff = (-1) *Weeknow; //first day of the week stringFirstDay = DateTime. AddDays (Daydiff). ToString ("YYYY-MM-DD"); returnConvert.todatetime (FirstDay); } /// <summary> ///get the first day of the week (first day of Monday)/// </summary> /// <param name= "datetime" ></param> /// <returns></returns> Publicdatetime Getweekfirstdaymon (datetime datetime) {//Monday for the first day intWeeknow =Convert.ToInt32 (DateTime. DayOfWeek); //because it is the first day of Monday, so to judge Weeknow equals 0 o'clock, to push forward 6 days. Weeknow = (Weeknow = =0? (7-1): (Weeknow-1)); intDaydiff = (-1) *Weeknow; //first day of the week stringFirstDay = DateTime. AddDays (Daydiff). ToString ("YYYY-MM-DD"); returnConvert.todatetime (FirstDay); } /// <summary> ///get the last day of the week (Saturday is the last day)/// </summary> /// <param name= "datetime" ></param> /// <returns></returns> Publicdatetime Getweeklastdaysat (datetime datetime) {//Saturday is the last day intWeeknow =Convert.ToInt32 (DateTime. DayOfWeek); intDaydiff = (7-Weeknow)-1; //last day of the week stringLastday = DateTime. AddDays (Daydiff). ToString ("YYYY-MM-DD"); returnConvert.todatetime (Lastday); } /// <summary> ///get the last day of the week (Sunday is the last day)/// </summary> /// <param name= "datetime" ></param> /// <returns></returns> Publicdatetime Getweeklastdaysun (datetime datetime) {//Sunday is the last day intWeeknow =Convert.ToInt32 (DateTime. DayOfWeek); Weeknow= (Weeknow = =0?7: Weeknow); intDaydiff = (7-Weeknow); //last day of the week stringLastday = DateTime. AddDays (Daydiff). ToString ("YYYY-MM-DD"); returnConvert.todatetime (Lastday); } } }
C # Gets the first and last day of the week on which a date is located