Get the previous month's first and last day dates in c#

Question

var today = DateTime.Today;
var month = new DateTime(today.Year, today.Month, 1);       
var first = month.AddMonths(-1);
var last = month.AddDays(-1);

In-line them if you really need one or two lines.

The way I've done this in the past is first get the first day of this month

dFirstDayOfThisMonth = DateTime.Today.AddDays( - ( DateTime.Today.Day - 1 ) );

Then subtract a day to get end of last month

dLastDayOfLastMonth = dFirstDayOfThisMonth.AddDays (-1);

Then subtract a month to get first day of previous month

dFirstDayOfLastMonth = dFirstDayOfThisMonth.AddMonths(-1);

using Fluent DateTime https://github.com/FluentDateTime/FluentDateTime

        var lastMonth = 1.Months().Ago().Date;
        var firstDayOfMonth = lastMonth.FirstDayOfMonth();
        var lastDayOfMonth = lastMonth.LastDayOfMonth();

DateTime LastMonthLastDate = DateTime.Today.AddDays(0 - DateTime.Today.Day);
DateTime LastMonthFirstDate = LastMonthLastDate.AddDays(1 - LastMonthLastDate.Day);

I use this simple one-liner:

public static DateTime GetLastDayOfPreviousMonth(this DateTime date)
{
    return date.AddDays(-date.Day);
}

Be aware, that it retains the time.

An approach using extension methods:

class Program
{
    static void Main(string[] args)
    {
        DateTime t = DateTime.Now;

        DateTime p = t.PreviousMonthFirstDay();
        Console.WriteLine( p.ToShortDateString() );

        p = t.PreviousMonthLastDay();
        Console.WriteLine( p.ToShortDateString() );


        Console.ReadKey();
    }
}


public static class Helpers
{
    public static DateTime PreviousMonthFirstDay( this DateTime currentDate )
    {
        DateTime d = currentDate.PreviousMonthLastDay();

        return new DateTime( d.Year, d.Month, 1 );
    }

    public static DateTime PreviousMonthLastDay( this DateTime currentDate )
    {
        return new DateTime( currentDate.Year, currentDate.Month, 1 ).AddDays( -1 );
    }
}

See this link http://www.codeplex.com/fluentdatetime for some inspired DateTime extensions.