Receiving 'Expression being assigned must be constant' when it is

Question

Is there a way to use something like this:

private const int MaxTextLength = "Text i want to use".Length;

I think it would be more readable and less error prone than using something like:

private const int MaxTextLength = 18;

Are there any ways to have the length of the text be the source for a constant variable?

Answer 1

private readonly static int MaxTextLength = "Text i want to use".Length;

Answer 2

Use static readonly instead of const.

Constants have to be compile time constants

Answer 3

Unfortunately, if you are using the const keyword the value on the right side of the '=' must be a compile-time constant. Using a "string".length requires .NET code to execute which can only occur when the application is running, not during compile time.

You can consider making the field readonly rather than a const.

Answer 4

Does the value need to be a const? Would a static readonly work for your case?

private static readonly int MaxTextLength = "Text i want to use".Length;

This will allow you to write the code in a similar manner to your first example.