C++ Unresolved Externals because of header [duplicate] - c++

Question

This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 8 years ago.
I just started with C++ for some OpenGL applications and wanted to pack some monster functions into a util class so that my code remains clean. This is what I did:
awesomeClass.h :
#pragma once
class AwesomeClass
{
public:
static void do_something_awesome();
};
awesomeClass.cpp :
#include "awesomeClass.h"
void do_something_awesome(){
//...
}
main.cpp :
#include "awesomeClass.h"
int main(int argc, char** argv)
{
AwesomeClass::versuchen();
return 0;
}
Output:
Error 3 error LNK1120: 1 unresolved externals \Visual Studio 2013\Projects\TestEnvironmment\Debug\TestEnvironmment.exe TestEnvironmment
Error 2 error LNK2019: unresolved external symbol "public: static void __cdecl AwesomeClass::do_something_awesome(void)" (?do_something_awesome#AwesomeClass##SAXXZ) referenced in function _SDL_main \Visual Studio 2013\Projects\TestEnvironmment\TestEnvironmment\main.obj TestEnvironmment
What is wrong with that code? I mean it works when I paste everything in one file.

Answer 1

You should write
void AwesomeClass::do_something_awesome(){... }
Instead of
void do_something_awesome(){... }
Otherwise the function you implement does not belong to the class.

Answer 2

You should write this if you want write do_something_awesome in separate cpp file.
void AwesomeClass::do_something_awesome(){
//...
}
Or you can use:
#pragma once
class AwesomeClass
{
public:
static void do_something_awesome(){
//code here
}
};