Re: Problem with an enum in a switch statement

From:

Victor Bazarov <v.bazarov@comcast.invalid>

Newsgroups:

comp.lang.c++

Date:

Wed, 05 Sep 2012 15:51:47 -0400

Message-ID:

<k28agl$om0$1@dont-email.me>

On 9/5/2012 3:38 PM, army1987 wrote:

I have two types `eParticleType` and `Particle` defined as
     enum eParticleType {
         eNull,
         eNucleus,
         eMuon,
         eElectron,
         eProton,
         eNeutron,
         ePhoton,
         eNeutrino,
         ePion
     };
     class Particle {
       public:
         // lots of stuff
       private:
         eParticleType fType;
         // more stuff
     };
and a function defined as
     std::vector<Particle> PropagateParticle(Particle* input) {

Is that a member function? Because if it is, then it needs to be
defined slightly differently, probably:

std::vector<Particle> Particle::PropagateParticle( ...

And if it isn't, then what's "fType" in it?

         std::vector<Particle> output;
         // stuff

         switch(fType) {

           case eNeutron:

           case eProton:

           case eNucleus:

             output = PropagateNucleus(input);

             break;

           case eNeutrino:

             output = PropagateNeutrino(input);

             break;

           // etc.
           default:

             std::cerr << "Unsupported particle type" << std::endl;

             abort();

         }
         // stuff

         return output;

     }
(Each of the `PropagateXxx` functions has `assert(input->GetType() ==
eXxx;` at the beginning.)

When I compile this with g++, I get "warning: case label value exceeds
maximum value for type", and when I run the program I immediately get
"Assertion `input->GetType() == eMuon' failed.". What's going on? (And
no, I'd rather not have stuff like `class Nucleus: public Particle` etc.
for backward compatibility reasons.)

See FAQ 5.8 and follow its recommendations.

V
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