When you talk about informing other readers, consider the compiler itself as a reader. If a variable is declared static, that can affect the degree to which optimizations kick in. Redefining a static variable as extern is impossible, but the compiler will (as usual) give you enough rope to hang yourself. If I write static … Read more
Change your z.c to #include “a.h” #include “b.h” #include “global.h” int count; /* Definition here */ int main() { count = 0; functAb(); functBa(); return 0; } From global.h, all your files inherit the declaration of variable count but the definition is missing from all files. You must add the definition to one of the … Read more
You can link the standard c++ library with the -l flag to gcc: gcc cplusplus.o -lstdc++ -o myexe
One use of weak linking is implementing the replaceable functions in the C++ standard. Namely: void *operator new(std::size_t); void *operator new(std::size_t, std::nothrow_t const &) noexcept; void *operator new[](std::size_t); void *operator new[](std::size_t, const std::nothrow_t&) noexcept; void operator delete(void *) noexcept; void operator delete(void *, std::nothrow_t const &) noexcept; void operator delete[](void *) noexcept; void operator delete[](void … Read more
You probably need to link with the C++ support runtime library. This happens automatically when you invoke g++. On Linux, this is achieved by adding the -lstdc++ flag to the linker. You have to figure out how to do the same on your platform.
You don’t need to link to a different library, you need to use an older version of the compiler. Have a look at the GNU ABI policy. The libstdc++ shared library is designed to be forward compatible. I.e. version 6.0.10 can be used if you need 6.0.8. In the policy you can read that from … Read more
Libraries must be listed after the objects that use them (more precisely, a library will be used only if it contains a symbol that satisfies an undefined reference known at the time it is encountered). Move the -lmnl to the end of the command.
// file a.c // file-scope int a = 0; // goes into BSS after compilation of a.c into object file a.o, a symbol goes into BSS section. // file b.c // file-scope int b; // goes into COMMON section after compilation of b.c into object file b.o, b symbol goes into COMMON section. After linking … Read more