WebAug 23, 2011 · Declare functions/variables using extern in a header file (*.h/*.hh). Still, extern is optional for functions, but not for variables. So you don't normally see extern before functions in header files. In the calling *.c/*.cc file, #include the header, and call the function/variable as needed. WebJan 2, 2015 · The usual way to handle this is to make the header itself safe to use from C++. A C-only header might contain #ifndef H_MYCFILE #define H_MYCFILE #include void mycfunc1 (void); void mycfunc2 (int i); void mycfunc3 (size_t s); #endif Adapting this to make it safe to use from C++:
Name Mangling and extern "C" in C++ - GeeksforGeeks
Webc header extern multidimensional-array Share Improve this question Follow edited Dec 20, 2011 at 20:34 chrisaycock 36k 14 88 123 asked Dec 20, 2011 at 20:31 user1106072 331 2 4 8 Add a comment 7 Answers Sorted by: 22 You need, at a minimum, to include the right-most column size for a 2-D array. You can declare it like this: WebOct 3, 2012 · The extern keyword is used to share variables across translation units. When you declare variables in a header file, those variables are already included in the translation unit (.cpp) file that contains the header file. Therefore, any C++ file that … bodyworks gym new london sub base
c - Why would you use `extern void my_func();` rather than …
WebJan 19, 2013 · Yes, extern can be propagated in this way. The compiler only needs to see that the variable is declared extern at the point of usage it doesn't matter through which header. The content of the header files are merely pasted at the top of source file by the pre-processor. So the compiler doesn't even know of header files. WebMay 5, 2024 · Using "extern" internally only makes sense if you would want to "relay" a declaration from a header to a source in order to avoid complete recompilation of large code bases whenever a declaration changes. Or if you would not want constants (or whatever) to be included multiple times in the code. Example 1: WebFeb 4, 2024 · Yes, extern int a is only a declaration, but int b; is a tentative definition. You can look it up. – Nate Eldredge Feb 4, 2024 at 23:04 The only usage of extern used in header files that makes sense is with the global variables defined in the corresponding C file, which should also be accessible in other C files. – Eugene Sh. Feb 4, 2024 at 23:05 bodyworks gym near me