<< c

C Macro

# Macro Basic

# Define Constant By Macro

# Variadic Macro

Use ... to represent variable number of argument of marco and use __VA_ARGS__ identifer to expand it:

#define eprintf(...) fprintf(stderr, __VA_ARGS__)

C++ support the renaming of identifer, note that after renaming __VA_ARGS__ cannot be used:

#define eprintf(args...) fprintf(stderr, args)

We are able to use both variable length arugment with normal named arugment in the argument list:

#define eprintf(format, ...) fprintf(stderr, foramt, __VA_ARGS__)

In standard C if you left the variadic arugment empty it would be an error since the due to the tailling comma after marco expansion:

// eprintf()

Variadic marcos became a standard part of C with C99. GNU CPP previously supported them with a named variable argument, which is still supported fro backward compatibility.