Check Date Equals 1st Date of Month C# [closed]

Answer 1

Pass your date to this function:

public static void ConvertToFirstDate(ref DateTime dt){
    TimeSpan ts = dt.Subtract(new DateTime(dt.Year, dt.Month, 1));
    dt =  dt.AddDays(-ts.Days);
}

Answer 2

DateTime date = ... // your original date here...

// Don't bother checking, just create a new date for the 1st.
date = new DateTime(date.Year, date.Month, 1);

UPDATE: The OP has apparently changed the specs:

DateTime date = ... // your original date here...
if (date.Day != 1)
  date = new DateTime(date.Year, date.Month, 1).AddMonths(1);

(let the .AddMonths() method worry about the year rolling over in December...)

Answer 3

IMO, since you have a definite format you expect from users (MM\DD\YYYY) why not do a simple split and dig your hit:

string arbitDate = "4/3/2014";
string UsersFirstDay = arbitDate.Trim().Split(new String[] { "/" }, StringSplitOptions.RemoveEmptyEntries)[1].Trim();//index 1 is the DD part - according to your format
UsersFirstDay = (UsersFirstDay == "1") ? UsersFirstDay : "1";