Formatted MessageBox/AfxMessageBox

You often need to format a string and populate it with relevant data before displaying a message box. For example

int nAge = 27;
TCHAR sName[]="Ajay";
float nSalary = 12500.50;

// Declare variable
CString strMessage;

// Format
strMessage.Format( _T("Name is %s, Age is %d, and salary is %.2f"), 
    sName, nAge, nSalary);

// Then display.
AfxMessageBox(strMessage);

What if this can be acheived by single statement:

AfxMessageBoxFormatted(_T("Name is %s, Age is %d, and salary is %.2f"), 
   sName, nAge, nSalary);

And here is implementation of AfxMessageBoxFormatted:

void AfxMessageBoxFormatted(LPCTSTR pFormatString, ...)
{
    va_list vl;
    va_start(vl, pFormatString);

    CString strFormat;
    strFormat.FormatV(pFormatString, vl); // This Line is important!

    // Display message box.	
    AfxMessageBox(strFormat);
}

If you don't you MFC, or don't want to use, you can implement MessageBoxFormatted as:

void MessageBoxFormatted(HWND hWnd, LPCTSTR pCaption, LPCTSTR pFormatString, ...)
{
    va_list vl;
    va_start(vl, pFormatString);
    
    TCHAR strFormat[1024]; // Must ensure size!


    // Generic version of vsprintf, works for both MBCS and Unicode builds 
    _vstprintf(strFormat, pFormatString, vl);
	
    // Or use following for more secure code
    // _vstprintf_s(strFormat, sizeof(strFormat), pFormatString, vl)

    ::MessageBox(hWnd, strFormat, pCaption,MB_ICONINFORMATION);
}

And use it as:

MessageBoxFormatted(NULL,  // Or a valid HWND
    _T("Information"),
    _T("Name is %s, Age is %d, and salary is %.2f"),
    sName, nAge, nSalary);

If you don't understand stuff like TCHAR, LPCTSTR, _T, you better read this Tip/Trick: What are TCHAR, WCHAR, LPSTR, LPWSTR, LPCTSTR etc?[^]