The BOOST_PP_COMMA macro expands to a comma.

Usage

BOOST_PP_COMMA()

Remarks

The preprocessor interprets commas as argument separators in macro invocations.  Because of this, commas require special handling.

Requirements

Header:  <boost/preprocessor/punctuation/comma.hpp>

Sample Code

#include <boost/preprocessor/control/if.hpp>
#include <boost/preprocessor/facilities/empty.hpp>
#include <boost/preprocessor/punctuation/comma.hpp>

BOOST_PP_IF(1, BOOST_PP_COMMA, BOOST_PP_EMPTY)() // expands to ,