Sanya-ips/ipslib/Ips.Library.Basic/DateTime/DateTimeExtensions.cs

using System;

namespace Ips.Library.Basic
{
    public static class DateTimeExtensions
    {
        public static DateTime ClearTime(this DateTime dateTime)
        {
            return dateTime.Subtract(
                new TimeSpan(0, dateTime.Hour, dateTime.Minute, dateTime.Second, dateTime.Millisecond)
            );
        }

        public static DateTime ClearMinute(this DateTime dateTime)
        {
            return dateTime.Subtract(
                new TimeSpan(0, 0, dateTime.Minute, dateTime.Second, dateTime.Millisecond)
            );
        }

        public static DateTime ClearSecond(this DateTime dateTime)
        {
            return dateTime.Subtract(
                new TimeSpan(0, 0, 0, dateTime.Second, dateTime.Millisecond)
            );
        }

        public static DateTime ClearMillisecond(this DateTime dateTime)
        {
            return dateTime.Subtract(
                new TimeSpan(0, 0, 0, 0, dateTime.Millisecond)
            );
        }

        public static string Format(this DateTime source, string format = "yyyy-MM-dd HH:mm:ss")
        {
            return source.ToString(format);
        }

        public static string Format(this DateTime? source, string format = "yyyy-MM-dd HH:mm:ss")
        {
            return source?.ToString(format) ?? "";
        }
    }
}