build - Classes from C++ Primer going into Cyclic Dependency -

i following book - c++ primer learning c++. i'm in middle of chapter introducing classes, , i'm stuck in resolving header files include of 2 classes taken example there.

here 2 classes, , header files:

screencls.h:

#ifndef screencls_h #define screencls_h  #include <iostream>  #include "windowmanager.h"  using namespace std;  class screencls {     friend void windowmanager::clear(screenindex);  public:     typedef string::size_type pos;     screencls() { }     screencls(pos height, pos width, char c): height(height), width(width), contents(height * width, c) { }      screencls &set(char);     screencls &set(pos, pos, char);      char get() const { return contents[cursor]; }  // implicitly inline  private:     pos cursor;     pos height;     pos width;     string contents; };  #endif // screencls_h 

screencls.cpp:

#include "screencls.h"  char screencls::get(pos r, pos c) const {     pos row = r * width;     return contents[row + c]; }  screencls &screencls::set(char ch) {     contents[cursor] = ch;     return *this; }  screencls &screencls::set(pos r, pos c, char ch) {     contents[r * width + c] = ch;     return *this; } 

windowmanager.h:

#ifndef windowmanager_h #define windowmanager_h  #include <iostream> #include <vector> #include "screencls.h"  using namespace std;  class windowmanager {  public:     // location id each screen on window     using screenindex = vector<screencls>::size_type;     // reset screen @ given position blanks     void clear(screenindex);  private:     vector<screencls> screens{ screen(24, 80, ' ') }; };  #endif // windowmanager_h 

windowmanager.cpp:

#include "windowmanager.h" #include "screencls.h"  void windowmanager::clear(screenindex index) {     screencls &s = screens[i];     s.contents = string(s.height * s.width, ' '); } 

this project structure:

/src/screencls.cpp  /src/windowmanager.cpp  /include/screencls.h  /include/windowmanager.h 

i'm using code::blocks ide. i've added /src , /include folder in search directory in compiler settings. i've added project root directory search directory.

now, when i'm trying build project, shows following errors:

'screencls' not declared in scope (windowmanager.h)   'screenindex' has not been declared (windowmanager.h)   'screenindex' has not been declared (screencls.h)   

and i've no idea what's happening here. searched through resources online, , found this link. , it's not helping here. can take time , suggest solution?

it's simple:

your program #includes "screencls.h" in turn includes "windowmanager.h". #include of "screencls.h" in "windowmanager.h" nothing because has been included , windowmanager.h not know screencls is.

you need forward declaration instead means either declare of class necessary or use pointers.