C#转换 某日是今年第几天/第几週

加入using System.Globalization;
测试时请把参数d改成"yyyyMMdd"格式,例如"20230614"
主要转换属性为DateTime.DayOfYear及GregorianCalendar.GetWeekOfYear()

1.天数

DateTime date = DateTime.ParseExact("20240229", "yyyyMMdd", CultureInfo.InvariantCulture);int day = date.DayOfYear;Console.WriteLine(day);

2.週数

public static int W(string d){    DateTime date = DateTime.ParseExact(d, "yyyyMMdd", CultureInfo.InvariantCulture);    int week = GetWeekOfYear(date);    return week;}private static int GetWeekOfYear(DateTime dt){    GregorianCalendar gc = new GregorianCalendar();    return gc.GetWeekOfYear(dt, CalendarWeekRule.FirstDay, DayOfWeek.Monday);}