Question

I have produced this C++ code:

class TestInstance
{
    public:
        TestInstance();
        ~TestInstance();
        static TestInstance& GetInstance();

    private:
        static TestInstance* testInstance;
};

But I got this error when compiling:

error LNK2001: unresolved external symbol “private: static class
TestInstance* TestInstance::testInstance”
(?testInstance@TestInstance@@0PAV1@A)

fatal error LNK1120: 1 unresolved externals

Any idea?

Answer 1

Yes, initialize the static member in an implementation file.

//TestInstance.cpp
TestInstance* TestInstance::testInstance = NULL;