A preprocessing token is the minimal lexical element of the language in translation
phases 3 through 6.
In this document,
glyphs are used to identify
elements of the basic character set ([lex.charset]
The categories of preprocessing token are: header names,
placeholder tokens produced by preprocessing import
, and export-keyword
identifiers, preprocessing numbers, character literals (including user-defined character
literals), string literals (including user-defined string literals), preprocessing
operators and punctuators, and single non-whitespace characters that do not lexically
match the other preprocessing token categories.
If a U+0027 apostrophe
or a U+0022 quotation mark
matches the last category, the behavior is undefined.
If any character not in the basic character set matches the last category,
the program is ill-formed.
Preprocessing tokens can be separated by
this consists of comments ([lex.comment]
), or whitespace characters
U+0009 character tabulation
U+000b line tabulation
U+000c form feed
), or both.
As described in [cpp]
, in certain
circumstances during translation phase 4, whitespace (or the absence
thereof) serves as more than preprocessing token separation.
can appear within a preprocessing token only as part of a header name or
between the quotation characters in a character literal or