How to check if an enum variable is valid?

Question

I have an enum:

enum myenum{
  typeA,
  typeB,
  typeC
} myenum_t;

Then, a functions is to be called with an enum parameter:

int myfunction(myenum_t param1)
{
  switch(param1)
  {
    case typeA:
    case typeB:
    case typeC:
      //do the work
      break;

    default:
      printf("Invalid parameter");
  }
  return 0;
}

But, as myenum_t grows with more and more values, myfunction doesn't seem so elegant.

Is there a better way to check if an enum is valid or not?

Answer 1

A common convention for this is to do something like this:

typedef enum {
  typeA,
  typeB,
  typeC,
  num_types
} myenum_t;

Then you can check for (t < num_types).

If you subsequently add more enums, e.g.

typedef enum {
  typeA,
  typeB,
  typeC,
  typeD,
  typeE,
  num_types
} myenum_t;

then num_types is automatically updated and your error checking code doesn't need to change.