@yigit.aybey , Suppose the User enters the Date as "04/06/2022"
.
We can use the Below Expression to Check if it is a Weekend or not :
weekendList.Any(Function(x)x.Equals(DateTime.ParseExact("04/06/2022","dd/MM/yyyy",System.Globalization.CultureInfo.InvariantCulture).DayOfWeek.ToString))
Here, weekendList
is a Array of String variable which consists the weekend day names.
It would be better to restrict the user to put the date in a particular format and then use the format in the DateTime.ParseExact
method.
More on DateTime you can find below :