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:

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.