c++ - Cannot get SHGetKnownFolderPath() function working -

i having troubles using shgetknownfolderpath() function. getting following error message: type error in argument 1 'shgetknownfolderpath'; expected 'const struct _guid *' found 'struct _guid'.

in knowfolders.h have following relevant definitions:

#define define_known_folder(name,l,w1,w2,b1,b2,b3,b4,b5,b6,b7,b8) \     extern_c const guid name ... define_known_folder(folderid_programfiles,0x905e63b6,0xc1bf,0x494e,0xb2,0x9c,0x65,0xb7,0x32,0xd3,0xd2,0x1a); 

i using pelles c compiler .

this sample code:

#include <windows.h> #include <wchar.h> #include <knownfolders.h> #include <shlobj.h>  int wmain(int argc, wchar_t **argv) {      pwstr path = null;      hresult hr = shgetknownfolderpath(folderid_programfiles, 0, null, &path);          if (succeeded(hr)){          wprintf(l"%ls", path);     }      cotaskmemfree(path);      return 0; } 

how fix error message?

edit have found code examples shgetknownfolderpath(); of them execute function without pointer. instance:

hr = shgetknownfolderpath(folderid_public, 0, null, &pszpath); if (succeeded(hr)) {     wprintf(l"folderid_public: %s\n", pszpath);     cotaskmemfree(pszpath); } 

cppshellknownfolders.cpp

with comments of jonathan potter, able correct example.

the problem subtle. following code line looks c, c++.

hresult hr = shgetknownfolderpath(folderid_documents, 0, null, &path);

the shgetknownfolderpath() function has following prototype:

stdapi shgetknownfolderpath(refknownfolderid, dword, handle, pwstr*);

its first argument refknownfolderid.

in shtypes.h file find following:

#ifdef __cplusplus #define refknownfolderid const knownfolderid & #else #define refknownfolderid const knownfolderid * /*__midl_const*/ #endif /* __cplusplus */ 

this means, in c++ refknownfolderid reference , in c pointer. consequence, not need ampersand in c++ code first parameter. in visual c++ c code compiled c++ , distinction between languages blurred.

the second issue, unresolved external symbol 'folderid_programfiles'. error. error fixed adding #include <initguid.h> before #include <shlobj.h>. reason explained in article.

so following code compiles on pelles c.

#include <windows.h> #include <initguid.h> #include <knownfolders.h> #include <shlobj.h> #include <wchar.h>  int wmain(void) {      pwstr path = null;      hresult hr = shgetknownfolderpath(&folderid_documents, 0, null, &path);      if (succeeded(hr)) {         wprintf(l"%ls\n", path);     }      cotaskmemfree(path);      return 0; }