Unresolved External Symbol on Static Class Members

Unresolved external symbol on static class members

If you are using C++ 17 you can just use the inline specifier (see https://stackoverflow.com/a/11711082/55721)


If using older versions of the C++ standard, you must add the definitions to match your declarations of X and Y

unsigned char test::X;
unsigned char test::Y;

somewhere. You might want to also initialize a static member

unsigned char test::X = 4;

and again, you do that in the definition (usually in a CXX file) not in the declaration (which is often in a .H file)

C++ unresolved external symbol (public static int)

You have only declared night and night2, they still need definitions. (because they're static)

In your cpp file :

int HooksXD::night = 0;
int HooksXD::night2 = 0;

And then to access one don't do lmao.night, since it's a static you should access it through the type name : HooksXD::night.
Make sure you actually need static here though.

error LNK2001: unresolved external symbol private: static class

Put this into sound.cpp:

irrklang::ISoundEngine* Sound::_soundDevice;

NOTE: You might want to initialize it as well, for example:

irrklang::ISoundEngine* Sound::_soundDevice = 0;

static, but non-const data members should be defined outside of the class definition and inside the namespace enclosing the class. The usual practice is to define it in the translation unit (*.cpp) because it is considered to be an implementation detail. Only static and const integral types can be declared and defined at the same time (inside class definition):

class Example {
public:
static const long x = 101;
};

in this case you don't need to add x definition because it is already defined inside the class definition. However, in your case it is necessary. Extract from section 9.4.2 of the C++ Standard:

The definition for a static data member shall appear in a namespace scope enclosing the member’s class definition.

unresolved external symbol when accessing a static variable

You're doing that incorrectly.

class CommandManager {

public:
void sendText(std::string command);
static bool started; //NOT this -> bool CommandManager::started
//...
};

then put the definition of static member in .cpp file as:

#include "CommandManager.h" //or whatever it is

bool CommandManager::started = true; //you must do this in .cpp file

Now you can use CommandManager::started in your client code.

unresolved external symbol private: static int Math::result [duplicate]

Just add

int Math::result;

in your cpp file.

Math::result is declared as a static data variable in the definition of Math and should be defined somewhere. This can be the cpp file containing main() or any other to be found by the linker. You need not and should not repeat the keyword static at the definition.

By the way, you should avoid using namespace std; (or any other namespace) in a header file.

Static class template instance as member causes unresolved external symbol error

With

class A {
private:
static stack<int, 4> s;

// ...
};

you declare the static member s of the class A.

You have also to define it.

You have to add

stack<int, 4> A::s;

after the A body.

unresolved external symbol in class

You must define these variables like so (in your .cpp file, outside of any function):

double common::s_a;
double common::s_b;

This is a declaration (not a definition):

class common
{
static double common::s_a;
static double common::s_b;

This is a use (not a definition either):

common::common()
{
common::s_a = 100;
common::s_b = 100;
}

Unresolved external, trying to use static variable c++ [duplicate]

static Ground* ground = new Ground(10, 10);

You're missing World:: there, so you're defining a completely unrelated variable that just happens to have the same name. You should have this:

Ground* World::ground = new Ground(10, 10);


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