If, in the replacement list, a parameter is immediately
preceded by a
#
preprocessing token,
both are replaced by a single character string literal preprocessing token that
contains the spelling of the preprocessing token sequence for the
corresponding argument
.Each occurrence of white space between the argument's preprocessing
tokens becomes a single space character in the character string literal
.White space before the first preprocessing token and after the last
preprocessing token comprising the argument is deleted
.Otherwise, the original spelling of each preprocessing token in the
argument is retained in the character string literal,
except for special handling for producing the spelling of
string literals and character literals:
a
\
character is inserted before each
"
and
\
character of a character literal or string literal
(including the delimiting
"
characters)
.If the replacement that results is not a valid character string literal,
the behavior is undefined
.The character string literal corresponding to
an empty argument is
"".The order of evaluation of
#
and
##
operators is unspecified
.