Appending char/wide char to the c-string
#ifndef UNICODE
#define UNICODE
#endif

#include <stdio.h>
#include <Windows.h>

int main(void)
{
   TCHAR greeting[50] = L"Hello world";
   TCHAR exclamation=L'!';

 //????

wprintf("%s",greeting);

return 0;
}

TCHAR greeting[50] = L"Hello world";
TCHAR exclamation=L'!';

greeting[wcslen(greeting)+1] = L'';
greeting[wcslen(greeting)] = exclamation;