c++ - Setting an internal variable of an explicitly linked DLL -

i loading dll explicitly loadlibrary , use getprocaddress load function it. far good. following variable defined in header file of dll (readline.h):

readline_dll_impexp file *rl_outstream; 

this variable used internally dll, why have change "inside dll". new c++ , couldn't find way set variable in parent cpp file. tried:

hdll = loadlibrary("readline.dll"); hdll.rl_outstream = fopen("outstream.txt","w"); 

which yields following error:

error c2228: left of '.rl_outstream' must have class/struct/union type 'hinstance' did intend use '->' instead? 

1. how set dll variable correctly?
2. where should have searched find solution problem?

if need set variable inside dll. need export variable. consider following example:

we have dll:

#include <cstdio> #include <cassert>  #ifdef __cplusplus extern "c" { #endif  file *rl_outstream;  void do_something() {   assert(rl_outstream);    fputs("hello", rl_outstream); }  #ifdef __cplusplus }; #endif 

where there exported variable named rl_outstream, can set value this:

#include <windows.h> #include <cstdio> #include <cassert>  int main(int argc, char **argv) {   file **rl_outstream;   void (*do_something)(void);   hmodule hmodule;    hmodule = loadlibraryw(l"./lib.dll");   assert(hmodule);    rl_outstream = (file **) getprocaddress(hmodule, "rl_outstream");   assert(rl_outstream);    do_something = (void(*)(void)) getprocaddress(hmodule, "do_something");   assert(do_something);     *rl_outstream = fopen("out.txt", "w");   do_something();   fclose(*rl_outstream);    freelibrary(hmodule);   return 0; } 

after compiling , executing test.exe:

>g++ -wall lib.cpp -shared -o lib.dll >g++ -wall test.cpp -o test.exe >test.exe >type out.txt hello >