I cant print a number inside a formatted MessageBox - winapi

Question

The following code does not work as it should. %i does not connect with its variable.
#include<Windows.h>
#include<stdio.h>
#include<tchar.h>
/* SCREENSIZE.C
This project contains the code that Programming Windows
book by Charles Petzold is using.
*/
int cdecl MessageBoxPrintfW(TCHAR *msgBoxTitle, TCHAR *msgBoxFormat, ...)
{
//define buffer
TCHAR msgBoxBuffer[1024];
//define iteration pointer
va_list argPtr;
//start iteration
va_start(argPtr, msgBoxFormat);
/*int _vsnwprintf_s(
wchar_t *const _Buffer,
const size_t _BufferCount,
const size_t _MaxCount,
const wchar_t *const _Format,
va_list _ArgList)
*/
_vsntprintf_s(msgBoxBuffer, sizeof(msgBoxBuffer) / sizeof(TCHAR), (sizeof(msgBoxBuffer) / sizeof(TCHAR)) - 1, msgBoxFormat, argPtr);
//end iteration
va_end(argPtr);
//Use return type to pass preconfigured MessageBox(0,"Text","Title",MB_OKCANCEL);
//Whe we use L before a string example: L"text" it is considered UNICODE format.
return(MessageBox(0, msgBoxFormat, msgBoxTitle, MB_OKCANCEL));
}
int WINAPI WinMain(
HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR pCmdLine,
int iCmdShow)
{
int cxScreen, cyScreen;
cxScreen = GetSystemMetrics(SM_CXSCREEN);
cyScreen = GetSystemMetrics(SM_CYSCREEN);
MessageBoxPrintfW(TEXT ("SCREENSIZE"), TEXT("The screen is %i pixels wide by %i pixels high."), cxScreen, cyScreen);
return(0);
}
Why does this happen?
Below is the output that I get:

Answer 1

TCHAR msgBoxBuffer[1024];
_vsntprintf_s(msgBoxBuffer,...
...
return(MessageBox(0, msgBoxFormat, msgBoxTitle, MB_OKCANCEL));
Note that you are writting to msgBoxBuffer, but you never use msgBoxBuffer. So your message box doesn't change anything. Try the following instead:
int MessageBoxPrintfW(const TCHAR *msgBoxTitle, const TCHAR* msgBoxFormat, ...)
{
va_list args;
va_start(args, msgBoxFormat);
int len = _vsctprintf(msgBoxFormat, args) + 1; // add terminating '\0'
TCHAR *buf = new TCHAR[len];
_vstprintf_s(buf, len, msgBoxFormat, args);
int result = MessageBox(0, buf, msgBoxTitle, MB_OKCANCEL);
delete[]buf;
return result;
}
For C version use malloc(len * sizeof(TCHAR)) instead of new, and use free instead of delete[]