c++ - Building a DLL with VC++ function is inaccessible -

today needed small library recursively list files in folder , subfolders. decided create small library, simple , contains 2 functions:

bool __cdecl isdir(std::string dir); void __cdecl listdir(std::string dir, std::vector<std::string> &files, bool recursive); 

the function of these quiet self explanatory.

it contains 1 header file defines class fr , export using

__declspec( dllexport )

the reason me bothering small library can used in future projects without having incorporate source files projects time.

this how try call 1 of functions:

fr *clazz = new fr(); clazz->isdir("c:/path/to/dir"); 

and error generated:
intellisense: function "fr::isdir" (declared @ line 11 of "c:\dev\filerecursiondll\inc\fr.h") inaccessible

[fr.cpp]

#include "fr.h"  using namespace std;  bool apientry dllmain(handle hmodule,     dword  ul_reason_for_call,     lpvoid lpreserved) {     return true; }  dllexport bool __cdecl fr::isdir(string dir){     struct stat fileinfo;     stat(dir.c_str(), &fileinfo);     if (s_isdir(fileinfo.st_mode)){         return true;     }     else{         return false;     } }  dllexport void __cdecl fr::listdir(string dir, vector<string> &files, bool recursive){     dir *dp; //create directory object     struct dirent *entry; //create entry structure     dp = opendir(dir.c_str()); //open directory converting string const char*     if (dir.at(dir.length() - 1) != '/'){         dir = dir + "/";     }     if (dp != null){ //if directory isn't empty         while (entry = readdir(dp)){ //while there in directory             if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0){ //and if entry isn't "." or ".."                 if (isdir(dir + entry->d_name) == true && recursive == true){//check if new path directory, , if (and recursion specified true), recurse.                     files.push_back(string(entry->d_name)); //add entry list of files                     listdir(dir + entry->d_name, files, true); //recurse                 }                 else{                     files.push_back(string(entry->d_name));//add entry list of files                 }             }         }         (void)closedir(dp); //close directory     }     else{         perror("couldn't open directory.");     } } 

[fr.h]

#ifndef fr_h #define fr_h  #define dllexport   __declspec( dllexport )   #include<dirent.h> #include<vector>  class dllexport fr {     bool __cdecl isdir(std::string dir);     void __cdecl listdir(std::string dir, std::vector<std::string> &files, bool recursive); }; #endif 

note: reference library doing appreciated!

thanks in advance!

class members private default, struct members public default.

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that said, why not general , simple create , use header-only module instead of adding complexity of compiler-specific dll.

also, windows programming better use wide character strings (i.e. unicode).

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example:

#pragma once // copyright (c) 2014 alf p. steinbach  #undef unicode #define unicode #include <windows.h>  #include <string>           // std::wstring #include <vector>           // std::vector  namespace filesystem{     using std::wstring;     using std::vector;      inline     auto path_join( wstring const& a, wstring const& b )         -> wstring     {         int const len_a = a.length();         int const len_b = b.length();          if( len_a == 0 ) { return b; }         if( len_b == 0 ) { return a; }          wstring result = a;         if( a[len_a - 1] == l'\\' )         {             if( b[0] == l'\\' ) { result.resize( len_a - 1 ); }         }         else if( b[0] != l'\\' )         {             result += l'\\';         }         result += b;         return result;     }       enum recursion { no_recursion, recursive };      inline     auto directory_entries( wstring const& directory_path, recursion const r = no_recursion )         -> vector<wstring>     {         vector<wstring> result;         win32_find_data state = {};         handle const h = findfirstfile( path_join( directory_path, l"*.*" ).c_str(), &state );         for(             bool more = (h != invalid_handle_value);             more;             more = !!findnextfile( h, &state )             )         {             result.push_back( state.cfilename );             if( r == recursive && !!(state.dwfileattributes & file_attribute_directory) )             {                 // todo: check isn't "." or ".." or (hard problem) circular symlink entry.                 bool const is_true_subdirectory = false;        // <-- here.                 if( is_true_subdirectory )                 {                     auto const sub_entries = directory_entries(                         path_join( directory_path, state.cfilename ), recursive                         );                     for( auto const& e : sub_entries )                     {                         result.push_back( e );                     }                 }             }         }         findclose( h );         return result;     }  }  // namespace filesystem