F.8.1 Global transformations
1 Floating-point arithmetic operations and external function calls may entail side effects
which optimization shall honor, at least where the state of the FENV_ACCESS pragma is
‘‘on’’. The flags and modes in the floating-point environment may be regarded as global
variables; floating-point operations (+, *, etc.) implicitly read the modes and write the
flags.
外部变量不是全局的难道还是本地的?
4.6 Static Variables
The variables sp and val in stack.c, and buf and bufp in getch.c, are for the private use of
the functions in their respective source files, and are not meant to be accessed by anything else.
The static declaration, applied to an external variable or function, limits the scope of that
object to the rest of the source file being compiled. External static thus provides a way to
hide names like buf and bufp in the getch-ungetch combination, which must be external so
they can be shared, yet which should not be visible to users of getch and ungetch.
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