Question

This is really puzzling me. For some reason I get a

“c1 not declared in this scope”

error from the compiler. I am usig Mingw with Code::Blocks. I would assume global variables are global to the program? Am I wrong? TYIA -Roland

    // main.h
    #include <iostream>

    #include "classone.cpp"
    #include "classtwo.cpp"

    extern AnotherClass c2;
    extern TheClass c1;


----------

    // main.cpp
    #include "main.h"

    AnotherClass c2;
    TheClass c1;

    int main()
    {

        c1.function5();
        c2.function2();

        return 0;
    }


----------

    //classone.h

    #include "main.h"
    class AnotherClass  {
    `
          public:
        void function2();

    void function3();

      private:
    int varone;
    int vartwo;
};


----------

// classone.cpp

#include "classone.h"

void AnotherClass::function2()  {

    std::cout << "Function 2 Check\n";
}

void AnotherClass::function3()  {

    std::cout << "Function 3 Check";
}


----------

// classtwo.h

#include "main.h"
class TheClass  {

      public:
    void function4();
    void function5();
};


----------

// classtwo.cpp
#include "classtwo.h"

void TheClass::function4()  {

    c1.function2();
    std::cout << "Function 2 Check\n";
}

void TheClass::function5()  {

    std::cout << "Function 3 Check";
}

Answer 1

It’s quite silly to include .cpp files like that – only include headers.

Anyway, change main.h to this:

#include <iostream>
extern AnotherClass c2;
extern TheClass c1;

Add this to main.cpp:

AnotherClass c2;
TheClass c1;

Then include main.h in each file which needs it, like this:

// classtwo.cpp
#include "classtwo.h"
#include "main.h"

void TheClass::function4()  {

    c1.function2();
    std::cout << "Function 2 Check\n";
}

void TheClass::function5()  {

    std::cout << "Function 3 Check";
}

Also, you need include guards if you don’t have those already.