Question

In such form…

#ifndef UNICODE
#define UNICODE 
#endif


#include <Windows.h>
#include <iostream>

class A
{
public:
    void makeFoo(TCHAR* output)
    {
        wcscpy(outputBuffer,TEXT("Hello world ♥"));
    }
private:
    static const int MAX_OUTPUT_SIZE=2000;  
    static TCHAR outputBuffer[MAX_OUTPUT_SIZE];
};


int main()
{
    TCHAR string[255];

    A example;

    example.makeFoo(string);

    MessageBox(0,string,0,0);

    system("Pause");
    return 0;
}

… we have a
linking error!

1>main.obj : error LNK2001: unresolved external symbol “private:
static wchar_t * A::outputBuffer” (?outputBuffer@A@@0PA_WA)

Answer 1

The linker error occurs because you have not provided a definition for the A::outputBuffer anywhere. Fix this by writing this in file scope:

TCHAR A::outputBuffer[A::MAX_OUTPUT_SIZE];

The value of string is unexpected because that buffer is uninitialized; makeFoo does nothing with its argument, and you do not initialize the buffer manually. Therefore it can contain anything at all (“garbage”).