MFC Registry: How to store the application settings in registry?

Q: How to store and retrieve the MFC application settings in/from registry?

A: By using the following CWinApp member functions:

• 'CWinApp::GetProfileString()'
• 'CWinApp::GetProfileInt()'
• CWinApp::WriteProfileString()'
• CWinApp::WriteProfileInt()'

Before calling any of above functions, you have to call 'CWinApp::SetRegistryKey()'. This causes application settings to be stored in the registry instead of regualr INI files.

Further, 'CWinApp' registry functions will read/write under 'HKEY_CURRENT_USER\Software\<'lpszRegistryKey' argument of 'SetRegistryKey()'>\<'lpszSection' argument of 'CWinApp' registry function>'.

Here is an example of an application that stores last "User Name" for login (e.g. to a database) to be used in subsequent application instances:

Code:

---

class CMyApp : public CWinApp
{
  // ...
  // Attributes
protected:
  CString m_strUserName;
  LPCTSTR const m_pszLoginSection;
  LPCTSTR const m_pszUserNameEntry;
  // ...

  // Operations
public:
  void GetUserName(CString& strUserName) const
  {
    strUserName = m_strUserName;
  }

  void SetUserName(LPCTSTR pszNewValue)
  {
    m_strUserName = pszNewValue;
  }

  //...
};

CMyApp::CMyApp() : m_pszLoginSection(_T("Login")),
                  m_pszUserNameEntry(_T("User Name"))
{
}

BOOL CMyApp::InitInstance()
{
  // ...
  // Change the registry key under which our settings are stored.
  // Usually it's the company name.
  SetRegistryKey(_T("Zerolei Software"));

  // Read "User Name" registry entry (value) from
  // HKEY_CURRENT_USER\Software\Zerolei Software\MyApp\Login key
  m_strUserName = GetProfileString(m_pszLoginSection, m_pszUserNameEntry);

  // ...
  return TRUE;
}

int CMyApp::ExitInstance()
{
  // write 'm_strUserName' in "User Name" registry entry (value) under
  // HKEY_CURRENT_USER\Software\Zerolei Software\MyApp\Login key
  WriteProfileString(m_pszLoginSection, m_pszUserNameEntry, m_strUserName);

  // ...
  return CWinApp::ExitInstance();
}

void CMainFrame::OnLogin()
{
  CMyApp* pApp = (CMyApp*)AfxGetApp();
  CLoginDialog dlgLogin;
  pApp->GetUserName(dlgLogin.m_strUserName);

  // ...

  if(IDOK == dlgLogin.DoModal())
  {
    pApp->SetUserName(dlgLogin.m_strUserName);
    //...
  }
}

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