FirstDayOfMonth / LastDayOfMonth

public static class DateExtensions
{
	public static string FirstDayOfMonth(this DateTime date)
	{
		return new DateTime(date.Year, date.Month, 1).ToString("MM/dd/yyyy");
	}

	public static string LastDayOfMonth(this DateTime date)
	{
		return new DateTime(DateTime.Now.Year, DateTime.Now.Month + 1, 1).AddDays(-1).ToString("MM/dd/yyyy");
	}
}
Example: 
DateTime dateToday = DateTime.Now;

Console.WriteLine("First Day: {0}", dateToday.FirstDayOfMonth());
Console.WriteLine("Last Day: {0}", dateToday.LastDayOfMonth());

Description

Simple way to Get the first and last day of the specified date.

Details

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