CODEWITHSUNDEEP
c++staticenums
rainbowgoblin
rainbowgoblin

Reputation: 1281

C++ static member variable of type enum won't compile

I'm trying to write a class with a public enum, and a private static member variable of that enum type. I can initialise the value of the static variable, but if I try to access it in a class member function, my code won't link. Here's a simple working example that will compile with:

g++ -o TestClass.o TestClass.cpp

but then fails when I try to compile/link the main source file with:

g++ -o test TestClass.o testmain.cpp

The error I get is:

Undefined symbols for architecture x86_64:
  "TestClass::_enum", referenced from:
      TestClass::printEnum()     in TestClass.o
ld: symbol(s) not found for architecture x86_64

I'm using a Mac running OSX 10.7.5, with gcc 4.2.1.

TestClass.h:

#ifndef TEST_CLASS_H
#define TEST_CLASS_H

class TestClass
{
public:
  TestClass() {};  
  void printEnum();

  typedef enum {A, B, C} MyEnum;

private:
  static MyEnum _enum;


};

#endif

TestClass.cpp:

#include "TestClass.h"

#include <iostream>
using namespace std;

TestClass::MyEnum _enum = TestClass::A;

void TestClass::printEnum()
{
  cout << "Value of enum: " << _enum << endl;
}

testmain.cpp:

#include "TestClass.h"

int main()
{
  TestClass tc;

  tc.printEnum();
}

Upvotes: 2

Views: 4433

Answers (2)

shivakumar
shivakumar

Reputation: 3397

Static member outside class is not defined properly proper format: classname::enumtype staticmember = value;

in your example it is TestClass::MyEnum _enum = TestClass::A;

Upvotes: 0

Chad
Chad

Reputation: 19032

The code below declares a file local variable _enum of type TestClass::MyEnum. It is not providing the definition for your static member variable.

TestClass::MyEnum _enum = TestClass::A;

To do that, you have to specifically define it in the appropriate class scope, like this:

TestClass::MyEnum TestClass::_enum = TestClass::A;

Upvotes: 3

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