Get array, value at index from typedef enum in C

Question

If have an enumeration like so:

typedef enum {
    ValueOne = /* some arbitrary number, NOT necessarily 0 */,
    ValueTwo = /* another number, NOT necessarily consecutive */
} MyEnumeration;

I was wondering if there is any way to get an array out of it and access a value at a specific index without doing this:

int array[2] = {ValueOne, ValueTwo};
MyEnumeration value = array[provided_index];

My problem is that in my project, the enumerations have 10-15 values, and I'd rather not create an array out of each one of them.

[Edit]: I can see how this would not be possible since typedef and enum aren't tied together at all, but I figured it wouldn't hurt to ask in case I was missing something.

Oliver Charlesworth · Accepted Answer · 2012-07-04 23:18:34Z

5

No.

You will have to write the code for both the enum and the array, or use some technique to auto-generate code to reduce the maintenance burden.

This article may of be some interest to you: The New C: X Macros.

answered Jul 4, 2012 at 23:18

Oliver Charlesworth

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1 Comment

reuben Over a year ago

+1 for the reference to X macros. I didn't know it under that name, but it's a technique I find invaluable for C programming.

Void Star · Accepted Answer · 2012-07-04 23:56:45Z

-2

I would completely do away with the enumeration. If you have to store it in both an array and as an enumeration, there is really no point to it at all. Enumerations are macros, they don't really store any information, they just create names for numbers, which I believe are substituted in at compile time. You might be better off just remembering which numbers to use for certain names in your head or using #define.

answered Jul 4, 2012 at 23:56

Void Star

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8 Comments

Oliver Charlesworth Over a year ago

"You might be better off just remembering which numbers to use for certain names in your head" - is that a joke?

Void Star Over a year ago

No, why would you think it is? The enum doesn't add any functionality to C, just convenience. When it ceases to be convenient, you're better off not using it.

Void Star Over a year ago

Well, you can comment them. I see nothing objectionable about it. And like I said, #define could also do the job.

Oliver Charlesworth Over a year ago

Commenting magic numbers still leaves a maintenance problem (what if I want to change all the values?). #defines are better than nothing, but debuggers usually understand enums. Enums also express intent better (when used appropriately).

aopsfan Over a year ago

My project is a rather extreme example of what an incredibly horrible idea "magic numbers" are...I have an enumeration of World Health Organization racial codes...for the six we are using in our app, the values are 10025, 20289, 20545, 20768, 21063, and 21311. They each represent a different race. Also the idea of using #define has no application to my question, how would it possibly help me? ...-1

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