의미없는 do while 문

do while(0) 이코드를 보면서 왜 이렇게 했을까 많이 고민해봤지만.. 도무지 답이 안 나왔었는데.. 좋은 정보 감사드립니다. ^^

do{..}while(0)문을 보고 왜 이렇게 쓸데없는 짓(?)을 할까 생각했던 적이 많았는데 이런 깊은 의미가 있었네요..

정보 감사합니다.

int main(int argc,char *argv[])
{
        if(argc==1) ; printf("A"); printf("B");;
}

gcc에서는 이렇게 변환되는군요

gcc -C -E로 하신후에 처리되는거 보시면 아실겁니다.

으음...
저도 예전에 저런 매크로에 관한 문제를 해결했었는데..
어떻게 했는지 다시 뒤져 보니 이렇게 썼더군요.. ㅎㅎ

#if defined(_DEBUG) || defined(TRACE_DEBUG)

#include <windows.h>
#include <tchar.h>

#ifndef TRACELOG_FILENAME
#	define TRACELOG_FILENAME "trace.log"
#endif

class CTracer
{
public:
	static CTracer* s_pcTrace;
	CRITICAL_SECTION m_crit;
	TCHAR* m_szFileName;
	TCHAR m_szBuffer[512];

	static void GrobalInitial(void);

	CTracer(const TCHAR* szLogFile);
	virtual ~CTracer();

	void Lock(void);
	void printf(const TCHAR* szFormat, ...);
	void Unlock(void);
};

#define TRACER CTracer::s_pcTrace

#define TRACE_INIT CTracer::GrobalInitial();

#define TRACE_PRINTF CTracer::s_pcTrace->printf

#define FUNC_OPEN(x); \
	TRACER->Lock(); \
	unsigned long __trace_time = GetTickCount(); \
	TCHAR* __trace_func = _T(x); \
	TRACER->printf(_T("%s | %s(%4d) | '%s' ┰ \n"), _T(__TIME__), strrchr(_T(__FILE__), _T('\\'))+1, _T(__LINE__), __trace_func); \
	TRACER->Unlock();

#define FUNC_RETURN_VOID \
	{ \
		TRACER->Lock(); \
		TRACER->printf(_T("%s | %s(%4d) | '%s' ┸ | time %dms\n"), _T(__TIME__), _tcsrchr(_T(__FILE__), _T('\\'))+1, _T(__LINE__), __trace_func, GetTickCount() - __trace_time); \
		TRACER->Unlock(); \
		return; \
	} __trace_time
#define FUNC_RETURN(x) \
	{ \
		TRACER->Lock(); \
		TRACER->printf(_T("%s | %s(%4d) | '%s' ┸ | time %dms | return-val 0x%08X(%d)\n"), _T(__TIME__), _tcsrchr(_T(__FILE__), _T('\\'))+1, _T(__LINE__), __trace_func, GetTickCount() - __trace_time, (unsigned long)x, (unsigned long)x); \
		TRACER->Unlock(); \
		return(x); \
	} __trace_time
#define FUNC_TRACE(x) \
	{ \
		TRACER->Lock(); \
		TRACER->printf(_T("%s | %s(%4d) | '%s' ┃ | time %dms | "), _T(__TIME__), _tcsrchr(_T(__FILE__), _T('\\'))+1, _T(__LINE__), __trace_func, GetTickCount() - __trace_time); \
		TRACER->printf(x); \
		TRACER->printf(_T("\n")); \
		TRACER->Unlock(); \
	} __trace_time
#define FUNC_PRINTF \
	{ \
		TRACER->Lock(); \
		TRACER->printf(_T("%s | %s(%4d) | '%s' ┃ | time %dms | "), _T(__TIME__), _tcsrchr(_T(__FILE__), _T('\\'))+1, _T(__LINE__), __trace_func, GetTickCount() - __trace_time); \
		TRACER->printf
#define PRINTF_END \
		; \
		TRACER->printf(_T("\n")); \
		TRACER->Unlock(); \
	} __trace_time

#else

inline void __trace_voidf(const char* szFormat, ...)
{ }

#define TRACE_INIT
#define TRACE_PRINTF __trace_voidf
#define FUNC_OPEN(x);
#define FUNC_RETURN_VOID return
#define FUNC_RETURN(x) return(x)
#define FUNC_TRACE(x);
#define FUNC_PRINTF __trace_voidf
#define PRINTF_END

#endif

#define _TI TRACE_INIT
#define _TP TRACE_PRINTF
#define _FO	 FUNC_OPEN
#define _FRV FUNC_RETURN_VOID
#define _FR  FUNC_RETURN
#define _FT  FUNC_TRACE
#define _FP  FUNC_PRINTF
#define PF_  PRINTF_END