16 Library introduction [library]

16.4 Library-wide requirements [requirements]

16.4.3 Using the library [using]

16.4.3.3 Linkage [using.linkage]

1
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Entities in the C++ standard library have external linkage.
Unless otherwise specified, objects and functions have the default extern "C++" linkage ([dcl.link]).
2
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Whether a name from the C standard library declared with external linkage has extern "C" or extern "C++" linkage is implementation-defined.
It is recommended that an implementation use extern "C++" linkage for this purpose.154
3
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Objects and functions defined in the library and required by a C++ program are included in the program prior to program startup.
4
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154)154)
The only reliable way to declare an object or function signature from the C standard library is by including the header that declares it, notwithstanding the latitude granted in ISO/IEC 9899:2018, 7.1.4.