Extern function in c file：Could we use extern "C" in C file without #ifdef

What is C extern Keyword?

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Effects of the extern keyword on C functions

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The extern keyword informs the compiler that the function or variable has external linkage - in other words, that it is visible from files other ...

extern Keyword in C

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Basically, the extern keyword extends the visibility of the C variables and C functions. That's probably the reason why it was named extern.

Extern – C and C++ Extern Keyword Function Tutorial

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The extern keyword in C and C++ extends the visibility of variables and functions across multiple source files. In the case of functions, the ...

What is an `extern` function in C?

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Applied to a function declaration, the extern keyword in fact does nothing: the declaration extern int incr(int) is exactly the same as int incr ...

C extern keyword

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An identifier declared in different scopes or in the same scope more than once can be made to refer to the same object or function by a process ...

How do I use extern to share variables between source files?

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Extern is the keyword you use to declare that the variable itself resides in another translation unit. So you can decide to use a variable in a ...

extern (C++)

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In C++, when used with a string, extern specifies that the linkage conventions of another language are being used for the declarator(s). C ...

CC++ 中的static

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我們人類用高階語言撰寫了各種source file，也就是各種的.h 和.cpp 檔 ... static 出現在variable 之前，且該variable 並不是宣告在某個function 中(C/C++) ...