Why is an if statement working but not a switch statement

Question

I'm trying to create a switch statement using the char index of a string and an Enum using this wrapper to get the value of the selected enum from a Description. It pretty much allows you to store a string to an enum value.

Here is my if statement:

if (msgComingFromFoo[1] == Convert.ToChar(Message.Code.FOO_TRIGGER_SIGNAL.EnumDescriptionToString())) {     //foo } 

and here is my switch statement:

switch (msgComingFromFoo[1]) {     case Convert.ToChar(Message.Code.FOO_TRIGGER_SIGNAL.EnumDescriptionToString()):         break; } 

Why is it accepting the if statement and not the switch? I tried converting it to a char since I'm selecting an index from a string, but unfortunately it didn't work.

Update:

Here is the Message.Code Enum

public class Message {     public enum Code     {         [Description("A")]         FOO_TRIGGER_SIGNAL     } } 

As you can see, I need the Description assigned to the enum not the enum value that is 0. Using Message.Code.FOO_TRIGGER_SIGNAL.EnumDescriptionToString() from the mentioned wrapper returns A not 0

Error:

A Constant Value Is Expected

Answer 1

You cannot have expressions in the case (prior to C# 7), but you can in the switch, so this will work:

switch (ConvertToMessageCode(msgComingFromFoo[1])) {     case Message.Code.FOO_TRIGGER_SIGNAL:         break; } 

Where you will need to write ConvertToMessageCode to do the necessary conversion to the Message.Code enum. ConvertToMessageCode just abstracts the conversion details, you may find you do not need a separate method, but can make do with inline code in the switch statement, e.g., a cast.