Question

I am using the following way to cout a function’s time:

#define TIME_COST(message, ...)\
 char szMessageBuffer[2048] = {0};\
 va_list ArgList;\
 va_start(ArgList, message);\
 vsprintf_s(szMessageBuffer, 2048, message, ArgList);\
 va_end(ArgList); \
 string strMessage(szMessageBuffer);\
 CQLogTimer t(strMessage);

// CQLogTimer is a self destructor,which will cout life time of its own and print szMessageBuffer.
However when I use the macro this :

void fun
{
TIME_COST("hello->%s", filePath);
XXXXXX
}

The message generated always is hello->(null)

Can Any one help?
Many thanks!

Answer 1

The correct version is:

#define TIME_COST(message, ...)\
 char szMessageBuffer[2048] = {0};\
 sprintf_s(szMessageBuffer, 2048, message, __VA_ARGS__);\
 string strMessage(szMessageBuffer);\
 CQLogTimer t(strMessage);

__VA_ARGS__ is not va_list type, but comma-separated arguments, so you need to use sprintf_s, not vsprintf_s.