Question

Example:

enum Flags
{
    A,
    B,
    C,
    D
};

class MyClass
{
   std::string data;
   int foo;

   // Flags theFlags; (???)
}

• How can I achieve that it is possible to set any number of the “flags” A,B,C and D in the enum above in an instance of MyClass?

My goal would be something like this:

if ( MyClassInst.IsFlagSet( A ) ) // ...
MyClassInst.SetFlag( A ); //...

• Do I have to use some array or vector? If yes, how?
• Are enums a good idea in this case?

Answer 1

// Warning, brain-compiled code ahead!

const int A = 1;
const int B = A << 1;
const int C = B << 1;
const int D = C << 1;

class MyClass {
public:
  bool IsFlagSet(Flags flag) const {return 0 != (theFlags & flag);}
  void SetFlag(Flags flag)         {theFlags |= flag;}
  void UnsetFlag(Flags flag)       {theFlags &= ~flag;}

private:
   int theFlags;
}