DBOUT(s) - pick one

dbout.c

// C style format (like printf)
// Source: http://systools.losthost.org/?code=3

void WINAPIV DBOUT(const TCHAR *fmt, ...)
{
	TCHAR s[1025] = { 0 };
	va_list args;

	va_start(args, fmt);
	wvsprintf(s, fmt, args);
	va_end(args);

	s[1024] = 0;

	OutputDebugString(s);
}

dbout.cpp

// C++ style format (like cout)
// Source: https://stackoverflow.com/a/1149623/2125072

#include <iostream>
#include <sstream>

#define DBOUT(s) \
{ \
	std::wostringstream os_; \
	os_ << s; \
	OutputDebugStringW( os_.str().c_str() ); \
}