In addition to all the names explicitly reserved, the 1990 ISO/IEC C standard also reserves (for implementations and future standards) names matching certain patterns:
Table 6–3 Names Reserved for Expansion
File |
Reserved Name Pattern |
---|---|
E[0-9A-Z].* |
|
ctype.h |
(to|is)[a-z].* |
locale.h |
LC_[A-Z].* |
math.h |
current function names[fl] |
signal.h |
(SIG|SIG_)[A-Z].* |
stdlib.h |
str[a-z].* |
string.h |
(str|mem|wcs)[a-z].* |
In the above lists, names that begin with a capital letter are macros and are reserved only when the associated header is included. The rest of the names designate functions and cannot be used to name any global objects or functions.