Re: [boost] [preprocessor] PP_CAT with symbols

On 24/09/2011 19:54, lcaminiti wrote:

Hello all,

I just want to confirm that the following:

BOOST_PP_CAT(old_size =, =)

correctly (and always) expands to:

old_size ==

I tested it on MSVC and GCC and it works. Plus from GCC documentation says about ##:

## can be used to concatenates two tokens into a single token.

I am asking because ## has some limitation (x ## = is not valid, etc) so I want to confirm my understanding is correct.

x= is not a valid token. What you want is just the sequence of the two tokens x and =, which is written as x =