The 1999 C standard introduces a range of new features into
C, including:
New language features, including new
keywords and identifiers, together with extended syntax for the
existing C90 language
New library features, including new libraries, and
new macros and functions for existing C90 libraries.
A selection of new features in C99 that are of interest to
developers using them for the first time, are discussed in the following
sections.
Note
C90 is compatible with Standard C++ in the sense that the
language specified by the standard is a subset of C++, except for
a few special cases. New features in the C99 standard mean that
C99 is no longer compatible with C++ in this sense.
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