Cannot access a class pointer from a different source file in the same project

[phenrol]

I am trying to access a pointer to a class that I defined in a separate source file from another one. Here is an example of what I have:

//myclass.h file
class testclass
{
public:
testclass::testclass(void);
int setintfunction(int testinteger);
int getintfunction(void);
testclass::~testclass(voide);
private:
int p_testinteger
};
 
testclass::testclass(void)
{
p_testinteger = 0
}
 
int testclass::setintfunction(int testinteger);
{
p_testinteger = testinteger;
return 0;
}
 
int testclass::getintfunction(void);
{
return p_testinteger;
}
 
testclass::~testclass(void);
{
}
 
//mysourcefile1.cpp
testclass* o_testclass = new testclass
int main
{
::o_testclass->setintfunction(13);
}
 
 
//mysourcefile2.cpp
int testfunction
{
printf("%d",::o_testclass->getintfunction());
}
 

To put this in further context, mysourcefile1.cpp is my main application source file and mysourcefile2.cpp is actually a dialog source file. The mysourcefile2.cpp file is called when I make a dlg.domodal call. The problem is that I am trying to get information from a class I instantiated in the main source file but I keep getting an error C2039: 'blahblah' : is not a member of '`global namespace'' when I try to call a function from the class I instantiated in the main source file. The strange thing is that when I put :: in front of the pointer variable I get a global listing of it in visual c++ and also get a listing with I put a -> after it for its public functions...I am at a loss. Please help.

Thanks,

Liam

[gpraghuram]

Hi,
There are couple of comilation errors in your code like jmissing semicolons and typo errors.
I have corrected the same .Try this

#include<stdio.h>
 
class testclass
{
public:
testclass::testclass(void);
int setintfunction(int testinteger);
int getintfunction(void);
~testclass(void);
private:
int p_testinteger;
};
 
testclass::testclass(void)
{
p_testinteger = 0;
}
 
int testclass::setintfunction(int testinteger)
{
p_testinteger = testinteger;
return 0;
}
 
int testclass::getintfunction(void)
{
return p_testinteger;
}
 
testclass::~testclass(void)
{
}
 
//mysourcefile1.cpp
testclass* o_testclass = new testclass;
int main()
{
::o_testclass->setintfunction(13);
}
 
 
//mysourcefile2.cpp
int testfunction()
{
printf("%d",::o_testclass->getintfunction());
}
 

Raghuram

[phenrol]

Thanks for the reply, but that did not work for me. I have a main source file that calls a dialog and I cannot get the dialog source file to use a class object that I created in the main source file. Here is the code that I have for a console MFC application:

//testclass.h file
class testclass
{
public:
    testclass::testclass(void);
    int setintfunction(int testinteger);
    int getintfunction(void);
    ~testclass(void);
private:
int p_testinteger;
};
 
testclass::testclass(void)
{
    p_testinteger = 0;
}
 
int testclass::setintfunction(int testinteger)
{
    p_testinteger = testinteger;
return 0;
}
 
int testclass::getintfunction(void)
{
    return p_testinteger;
}
 
testclass::~testclass(void)
{
}
 
//Dialog1.h file
#if !defined(AFX_DIALOG1_H__96E75EE7_F10A_44B0_8B55_D525D4FD4519__INCLUDED_)
#define AFX_DIALOG1_H__96E75EE7_F10A_44B0_8B55_D525D4FD4519__INCLUDED_
 
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
// Dialog1.h : header file
//
 
/////////////////////////////////////////////////////////////////////////////
// CDialog1 dialog
 
class CDialog1 : public CDialog
{
// Construction
public:
    CDialog1(CWnd* pParent = NULL);   // standard constructor
 
// Dialog Data
    //{{AFX_DATA(CDialog1)
    enum { IDD = IDD_DIALOG1 };
    CEdit    m_edit;
    //}}AFX_DATA
 
 
// Overrides
    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(CDialog1)
    protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
    //}}AFX_VIRTUAL
 
// Implementation
protected:
 
    // Generated message map functions
    //{{AFX_MSG(CDialog1)
    afx_msg void OnButton1();
    //}}AFX_MSG
    DECLARE_MESSAGE_MAP()
};
 
//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.
 
#endif // !defined(AFX_DIALOG1_H__96E75EE7_F10A_44B0_8B55_D525D4FD4519__INCLUDED_)
 
 
 
//lrsGlobalTest.cpp file
#include "stdafx.h"
#include "lrsGlobalTest.h"
#include "testClass.h"
#include "Dialog1.h"
 
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
testclass* o_testclass = new testclass;
/////////////////////////////////////////////////////////////////////////////
// The one and only application object
 
CWinApp theApp;
 
using namespace std;
 
int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
    int nRetCode = 0;
 
    // initialize MFC and print and error on failure
    if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(), 0))
    {
        // TODO: change error code to suit your needs
        cerr << _T("Fatal Error: MFC initialization failed") << endl;
        nRetCode = 1;
    }
    else
    {
        // TODO: code your application's behavior here.
        CString strHello;
        strHello.LoadString(IDS_HELLO);
        cout << (LPCTSTR)strHello << endl;
        ::o_testclass->setintfunction(13);
        printf("%d",::o_testclass->getintfunction());
        CDialog1 dlg;
        dlg.DoModal();
 
    }
 
    return nRetCode;
}
 
//Dialog1.cpp file
#include "stdafx.h"
#include "lrsGlobalTest.h"
#include "Dialog1.h"
 
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
 
/////////////////////////////////////////////////////////////////////////////
// CDialog1 dialog
 
 
CDialog1::CDialog1(CWnd* pParent /*=NULL*/)
    : CDialog(CDialog1::IDD, pParent)
{
    //{{AFX_DATA_INIT(CDialog1)
        // NOTE: the ClassWizard will add member initialization here
    //}}AFX_DATA_INIT
    //AfxMessageBox("test");
}
 
 
void CDialog1::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    //{{AFX_DATA_MAP(CDialog1)
    DDX_Control(pDX, IDC_EDIT1, m_edit);
    //}}AFX_DATA_MAP
}
 
 
BEGIN_MESSAGE_MAP(CDialog1, CDialog)
    //{{AFX_MSG_MAP(CDialog1)
    ON_BN_CLICKED(IDC_BUTTON1, OnButton1)
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()
 
/////////////////////////////////////////////////////////////////////////////
// CDialog1 message handlers
 
void CDialog1::OnButton1() 
{
    // TODO: Add your control notification handler code here
    int testint;
    char teststr[3];
    sprintf(teststr, "%d", ::o_testclass->getintfunction());
    m_edit.SetWindowText(teststr);
}
 

When I try to compile is says
C:\admin\vc++\lrsGlobalTest\Dialog1.cpp(51) : error C2039: 'o_testclass' : is not a member of '`global namespace''
C:\admin\vc++\lrsGlobalTest\Dialog1.cpp(51) : error C2065: 'o_testclass' : undeclared identifier
C:\admin\vc++\lrsGlobalTest\Dialog1.cpp(51) : error C2227: left of '->getintfunction' must point to class/struct/union

In my code, line 51 is the sprintf(teststr, "%d", ::o_testclass->getintfunction()); line.

Any ideas? A friend told me to try to use "extern" but I am unsure how to proceed with that idea.

Thanks

[Savage]

In my code, line 51 is the sprintf(teststr, "%d", ::o_testclass->getintfunction()); line.

Any ideas? A friend told me to try to use "extern" but I am unsure how to proceed with that idea.

Thanks

Why don't u put class testclass inside ur namespace?

Savage

[phenrol]

Why don't u put class testclass inside ur namespace?

Savage

Because I want to use it in the main source file and also in my dialog source file. I need the information from the instantiated object in both source files. The strange thing is that it acutally shows up in the global namespace in the dialog source file, I just can't use it for some reason.

[weaknessforcats]

Here is your situation:

//mysourcefile1.cpp
testclass* o_testclass = new testclass
 
//mysourcefile2.cpp
 

As you can see o_testclass is not in mysourcefile2.cpp. To use it, you meuch declare it in mysourcefile2.cpp.

//mysourcefile1.cpp
testclass* o_testclass = new testclass
 
//mysourcefile2.cpp
testclass* o_testclass = new testclass
 

But now you have TWO o_testclass variables and you want to use only the one in mysourcefile1.cpp. So, you use the extern storage class specifer and declare o_testclass to be a testclass* that is external to mysourcefile2.cpp

LIke this:

//mysourcefile1.cpp
testclass* o_testclass = new testclass
 
//mysourcefile2.cpp
extern testclass* o_testclass;
 

The compiler when compiling mysourcefile2.cpp will use the o_testclass pointer but will mark it as an "unresolved external reference". The linker will pick up on this and tie all the uses of o_testclass in mysourcefile2.cpp to the pointer o_testclass in mysourcefile1.cpp.

[phenrol]

I tried this and get the following compiler errors when I use "extern testclass* o_testclass;" in the other source file.

Dialog1.obj : error LNK2005: "public: __thiscall testclass::testclass(void)" (??0testclass@@QAE@XZ) already defined in lrsGlobalTest.obj
Dialog1.obj : error LNK2005: "public: int __thiscall testclass::setintfunction(int)" (?setintfunction@testclass@@QAEHH@Z) already defined in lrsGlobalTest.obj
Dialog1.obj : error LNK2005: "public: int __thiscall testclass::getintfunction(void)" (?getintfunction@testclass@@QAEHXZ) already defined in lrsGlobalTest.obj
Dialog1.obj : error LNK2005: "public: __thiscall testclass::~testclass(void)" (??1testclass@@QAE@XZ) already defined in lrsGlobalTest.obj
Debug/lrsGlobalTest.exe : fatal error LNK1169: one or more multiply defined symbols found
Error executing link.exe.

Hmm...what do you think?

[phenrol]

Anyone have any more ideas on this?

[vermarajeev]

Anyone have any more ideas on this?

What weaknessforcats tells is correct. Declare your class object as extern.
Also when you use extern object in main.cpp dont #include header file of that class..

Might help....

[phenrol]

So far, none of this advice has helped much. I still get the same error I posted when I use extern. If I had another way to do this I would, but I don't unfortunately. Any help would be greatly appreciated.

Thanks