Iterating over non-incremental Enum

Question

Before you ask, I\'ve looked and looked for this on SO, and cannot find a solid answer.

I need to be able to dynamically iterate over an enum that has non-incre

Answer 1

Use Higher Order macros

Here's the technique we've been using in our projects.

Concept:

The idea is to generate a macro called LISTING which contains the definition of name-value pairs and it takes another macro as an argument. In the example below I defined two such helper macros. 'GENERATE_ENUM' to generate the enum and 'GENERATE_ARRAY' to generate an iteratable array. Of course this can be extended as necessary. I think this solution gives you the most bang for the buck. Conceptually it's very similar to iammilind's solution.

Example:

// helper macros
#define GENERATE_ENUM(key,value)       \
      key = value                      \

#define GENERATE_ARRAY(name,value)     \
       name                            \

// Since this is C++, I took the liberty to wrap everthing in a namespace. 
// This done mostly for aesthetic reasons, you don't have to if you don't want.        
namespace CAPI_SUBTYPES 
{
    //  I define a macro containing the key value pairs
    #define LISTING(m)                 \ 
       m(NONE, 0),    /* Note: I can't use NULL here because it conflicts */
       m(DIAG_DFD, 1),                 \
       m(DIAG_ERD, 2),                 \
       ...
       m(DD_ALL, 13),                  \
       m(DD_COUPLE, 14),               \
       ...
               m(DIAG_SAD, 51),                \
       m(DIAG_ASG, 59),                \

    typedef enum {
       LISTING(GENERATE_ENUM)
    } Enum;

    const Enum At[] = {
       LISTING(GENERATE_ARRAY)
    };

    const unsigned int Count = sizeof(At)/sizeof(At[0]);
}

Usage:

Now in code you can refer to the enum like this:

CAPI_SUBTYPES::Enum eVariable = CAPI_SUBTYPES::DIAG_STD;

You can iterate over the enumeration like this:

for (unsigned int i=0; i

Note:

If memory serves me right, C++11 enums live in their own namespaces (like in Java or C#) , therefore the above usage wouldn't work. You'd have to refer to the enum values like this CAPI_SUBTYPES::Enum::FooBar.