C#: DateTime.DayOfWeek to string comparison

Question

This code is a simplified version of what I'm trying to do:

string day = Thursday;
DateTime dt = DateTime.Now;

if (day == dt.DayOfWeek)
{
     // start the program
}

I need to read a day of the week value from a database, assign it to a string, then compare the string to dt.DayOfWeek to check if the program should execute.

My error is this: "Operator '==' cannot be applied to operands of type 'string' and 'System.DayOfWeek"

Anyone know how to compare a string to a DateTime.DayOfWeek value?

objects in c# have a `.ToString()` method, most of the built-in ones actually parse the object inot a string — Sam I am says Reinstate Monica, Dec 04 '12 at 22:51
`I need to read a day of the week value from a database` what would return the DB. a number? or a string? — L.B, Dec 04 '12 at 22:54

score 15 · Answer 1 · answered Dec 04 '12 at 22:51

15

Use Enum.Parse to get the Enum value:

if ((DayOfWeek)Enum.Parse(typeof(DayOfWeek), day) == dt.DayOfWeek)

If you're not sure it's a valid value, there's TryParse<T>:

Enum val;
if (Enum.TryParse<DayOfWeek>(day, out val) && val == dt.DayOfWeek)

answered Dec 04 '12 at 22:51

McGarnagle

98,751
30
222
258

Alexei Levenkov · Accepted Answer · 2014-03-10T01:55:34.700

Easiest is to convert enum to string:

if (day == dt.DayOfWeek.ToString())...

Notes:

if you can change type of day to DayOfWeek enum you can avoid string comparisons (and its related localization/comparison issues).
if you have to use string make sure to decide if case is important or not (i.e. should "thursday" be equal to DayOfWeek.Thursday) and use corresponding String.Equals method.
consider converting string to enum with Parse as suggested in other answers: ((DayOfWeek)Enum.Parse(typeof(DayOfWeek), day)
make sure incoming string is always English - if it could be in other languages you'll need to look into manually matching value to one provided in CultureInfo.DateTimeFormat.DayNames.

But is not a very good practice. It's better to check the equality with enums directy — rpax, Mar 09 '14 at 23:49

score 3 · Answer 3 · answered Dec 04 '12 at 22:50

3

Try DayOfWeek day = DayOfWeek.Thursday;

answered Dec 04 '12 at 22:50

L.B

110,417
19
170
215

score 2 · Answer 4 · answered Dec 04 '12 at 22:53

2

You can use Enum.TryParse<DayOfWeek>:

string strDay = "Wednesday";
DayOfWeek day;
if (Enum.TryParse<DayOfWeek>(strDay, out day)
    && day == DateTime.Today.DayOfWeek)
{
    // ...
}

answered Dec 04 '12 at 22:53

Tim Schmelter

429,027
67
649
891

C#: DateTime.DayOfWeek to string comparison

4 Answers4

Linked

Related