Compiler Error CS1959

'name' is of type 'type'. The type specified in a constant declaration must be sbyte, byte, short, ushort, int, uint, long, ulong, char, float, double, decimal, bool, string, an enum-type, or a reference-type.

The types permitted in a const declaration are limited to those described in this message.

To correct this error

• Declare the constant with an allowed type.

Example

The following code produces CS1959 because null is not a type.

// cs1959.cs
class Program
    {
        static void Test<T>() where T : class
        {
            const T x = null; // CS1959
        }
    }

See Also

Reference

Constants (C# Programming Guide)

null (C# Reference)