CODEWITHSUNDEEP
c++classenums
Pete855217
Pete855217

Reputation: 1602

Right location for class enum

I think this is more a stylistic question, but I have a class with an enum for statistic distribution type (that is only used in this class):

Entity {
public:
  enum DistributionType {NORM, UNIFORM_INT, UNIFORM_SPECIFIED, BINOMIAL };
  distributionType ds;
...
}

I want to make a DistributionType value as a parameter for my constructor:

Entity salesVolume = new Entity(Entity::DistributionType.NORM);

but this doesn't work (I guess it expects DistributionType when it's being passed an int value?)

What is the right way to call a constructor with an enum value that is part of that same class? I could do it by typecasting to int, but this doesn't seem very tight. I could also exclude the enum from the class and define it separately (which I've seen) - is that a more common way to do it?

Thanks guys

Upvotes: 0

Views: 157

Answers (3)

David Stone
David Stone

Reputation: 28913

You can refer to it either as Entity::NORM or, more explicitly (in C++11), Entity::DistributionType::Norm.

However, on a stylistic note, this isn't Java. The code you showed will be slower and likely leak memory than just using the natural way of coding in C++, using automatic variables (variables created "on the stack"). Your code also won't compile because new gives you a pointer to the object. However, Instead of

Entity * salesVolume = new Entity(Entity::NORM);

Prefer

Entity salesVolume(Entity::NORM);

Upvotes: 1

saurabh jindal
saurabh jindal

Reputation: 121

Can you please what error are you getting, since this code should work, Only problems are that :

  1. you have defined ds as distributionType , while it should be DistributionType (capital "D").
  2. Entity salesVolume = new Entity(Entity::DistributionType.NORM); should be replaced with

Entity *salesVolume = new Entity(Entity::Entity.NORM);

Please Note the "*" before sa;esVolume. ie you have to declare it as pointer.

Upvotes: 0

juanchopanza
juanchopanza

Reputation: 227618

With enums, there is no "namespace", so you need this:

Entity* salesVolume = new Entity(Entity::NORM);

C++11 provides "enum classes" or "strongly typed enums" to solve this weirdness. It also allows you to use the enum name as a "scope" for traditional enums, so you could do this too:

Entity* salesVolume = new Entity(Entity::DistributionType::NORM); // C++11 only

Upvotes: 1

Related Questions