Flags enum in .NET

Question

I am trying to use a set of conditional statements that will set up an enumeration attributed with [Flags]. However, the compiler complains that 'm' is unassigned. How can I rewrite the following to achieve my intended functionality?

Media m;
if (filterOptions.ShowAudioFiles)
    m = m | Media.Audio;
if (filterOptions.ShowDocumentFiles)
    m = m | Media.Document;
if (filterOptions.ShowImageFiles)
    m = m | Media.Image;
if (filterOptions.ShowVideoFiles)
    m = m | Media.Video;

Answer 1

If none of the conditions are true m will be undefined. Set it to an initial value.

Answer 2

You need to initialize m. Create a "None" flag that has value 0 then:

Media m = Media.None;

Then the rest of your code.

Answer 3

Do you have a 'default' like filterOptions.ShowNone? If so, start off with m set to that. The compiler is complaining becuase at the end of all the if's, m might not be set to anything.

Answer 4

In addition to the above answers, besides the fact that this code seems pretty redundant, I'd like to suggest that you use a Select Case instead of all those ugly If's.

Answer 5

You could also write:

Media m = default(Media)

Useful in cases where you don't know the enum, class, or whether it's a value/reference type.