How to prevent duplicate values in enum?

Question

I wonder is there a way to prevent an enum with duplicate keys to compile?

For instance this enum below will compile

public         


        

Answer 1

public bool ValidateAllDistinct(Type enumType)
{
    return !Enum.GetNames(enumType).All(outerName
        => Enum.GetNames(enumType).Any(innerName
            => innerName == outerName 
                ? true 
                : Enum.Parse(enumType, innerName) != Enum.Parse(enumType, outerName)));
}

I simple test method for your unittest.

Answer 2

This isn't prohibited by the language specification, so any conformant C# compiler should allow it. You could always adapt the Mono compiler to forbid it - but frankly it would be simpler to write a unit test to scan your assemblies for enums and enforce it that way.

Answer 3

another solution to have unique values based on selected columns

var uniqueData = temp.Select(u => new tblschClassSchedule
            {
                TeacherName = u.TeacherName,
                SubjectName = u.SubjectName,

            }).Distinct() ;

this will get only 2 columns and only unique data for those columns

Answer 4

Unit test that checks enum and shows which particular enum values has duplicates:

[Fact]
public void MyEnumTest()
{
    var values = (MyEnum[])Enum.GetValues(typeof(MyEnum));
    var duplicateValues = values.GroupBy(x => x).Where(g => g.Count() > 1).Select(g => g.Key).ToArray();
    Assert.True(duplicateValues.Length == 0, "MyEnum has duplicate values for: " + string.Join(", ", duplicateValues));
}

Answer 5

Here's a simple unit test that checks it, should be a bit faster:

[TestMethod]
public void Test()
{
  var enums = (myEnum[])Enum.GetValues(typeof(myEnum));
  Assert.IsTrue(enums.Count() == enums.Distinct().Count());
}