Ryan Turek

C# DateTime Extensions

by · February 2, 2015

Hello! So for the past few weeks I’ve been working with a lot of DateTime logic in the app I’m developing, and I wrote some c# DateTime extension methods for my own purposes. I thought I’d share them in case anyone else could benefit from borrowing them. These are fairly limited right now but I will expand on them as I go.

Please feel free to give feedback and let me know where I could improve or change my code here. Thanks!

 Custom C# DateTime Extension Methods

[code lang=”csharp”] /// <summary>
/// Gets the 12:00:00 AM instance of a DateTime
/// </summary>
public static DateTime AbsoluteStart(this DateTime dateTime)
{
return dateTime.Date;
}

/// <summary>
/// Gets the 11:59:59 PM instance of a DateTime
/// </summary>
public static DateTime AbsoluteEnd(this DateTime dateTime)
{
return AbsoluteStart(dateTime).AddDays(1).AddTicks(-1);
}

/// <summary>
/// Gets the 12:00:00 AM instance of the first day of the month for a DateTime
/// </summary>
public static DateTime StartOfMonth(this DateTime dateTime)
{
return new DateTime(dateTime.Year, dateTime.Month, 1);
}

/// <summary>
/// Gets the 11:59:59 PM instance of the last day of the month for a DateTime
/// </summary>
public static DateTime EndOfMonth(this DateTime dateTime)
{
int daysInMonth = DateTime.DaysInMonth(dateTime.Year, dateTime.Month);
return AbsoluteEnd(new DateTime(dateTime.Year, dateTime.Month, daysInMonth));
}

/// <summary>
/// Gets the 12:00:00 AM instance of the first day of the month prior to the month for a DateTime
/// </summary>
public static DateTime StartOfPreviousMonth(this DateTime dateTime)
{
var oneMonthAgoToday = dateTime.AddMonths(-1);
return new DateTime(oneMonthAgoToday.Year, oneMonthAgoToday.Month, 1);
}

/// <summary>
/// Gets the 11:59:59 PM instance of the last day of the month prior to the month for a DateTime
/// </summary>
public static DateTime EndOfPreviousMonth(this DateTime dateTime)
{
var oneMonthAgoToday = dateTime.AddMonths(-1);
int daysInLastMonth = DateTime.DaysInMonth(oneMonthAgoToday.Year, oneMonthAgoToday.Month);
return AbsoluteEnd(new DateTime(oneMonthAgoToday.Year, oneMonthAgoToday.Month, daysInLastMonth));
}

/// <summary>
/// Gets the 12:00:00 instance of the first day of the standard Quarter for a DateTime
/// </summary>
public static DateTime StartOfStandardQuarter(this DateTime dateTime)
{
if (1 <= dateTime.Month && dateTime.Month <= 3)
return new DateTime(dateTime.Year, 1, 1);
else if (4 <= dateTime.Month && dateTime.Month <= 6)
return new DateTime(dateTime.Year, 4, 1);
else if (7 <= dateTime.Month && dateTime.Month <= 9)
return new DateTime(dateTime.Year, 7, 1);
else
return new DateTime(dateTime.Year, 10, 1);
}

/// <summary>
/// Gets the 11:59:59 PM instance of the last day of the standard Quarter for a DateTime
/// </summary>
public static DateTime EndOfStandardQuarter(this DateTime dateTime)
{
if (1 <= dateTime.Month && dateTime.Month <= 3)
return AbsoluteEnd(new DateTime(dateTime.Year, 3, 31));
else if (4 <= dateTime.Month && dateTime.Month <= 6)
return AbsoluteEnd(new DateTime(dateTime.Year, 6, 30));
else if (7 <= dateTime.Month && dateTime.Month <= 9)
return AbsoluteEnd(new DateTime(dateTime.Year, 9, 30));
else
return AbsoluteEnd(new DateTime(dateTime.Year, 12, 31));
}

/// <summary>
/// Converts the value of the current System.DateTime object to Coordinated Universal Time (UTC).
/// </summary>
public static DateTime? ToUniversalTime(this DateTime? dateTime)
{
return dateTime.HasValue
? dateTime.Value.ToUniversalTime()
: dateTime;
}
[/code]

More DateTime Extension Methods:
http://extensionmethod.net/csharp/datetime

Tags: