what applications ## preprocessor user gotchas consider?

as mentioned before questions, i'm operative by k&r, am now preprocessor. some-more engaging things — something i never knew before any before attempts learn c — ## preprocessor operator. according k&r:

the preprocessor user ##
provides proceed concatenate actual
arguments during macro expansion. a
parameter deputy calm is
adjacent ##, parameter is
transposed tangible argument, the
## surrounding white space are
removed, outcome re-scanned.
example, macro paste
concatenates the twin arguments:

#define paste(front, back) front ## back

so paste(name, 1) creates token
name1.

how since someone genuine world? receptive examples the use, there gotchas consider?