As title, calling GetWindowLongPtr (hWnd, GWLP_HINSTANCE) returns 0, general get error code GetLastError, unexpectedly is 0, the complete code is as follows:

 
#include  
#include  

using namespace std; 

Void testGetInstance () 
{
Const char * className="TaskSwitcherWnd"; 
Const char * windName="task switching"; 
HWND HWND=FindWindow (className, windName); 
Cout & lt; <"Window handle" & lt; Uint64_t tempHandle=GetWindowLongPtr (hWnd GWLP_HWNDPARENT); 
HWND hpWnd=* * (HWND) (& amp; TempHandle); 
Cout & lt; <"The parent window handle (from GetWindowLongPtr) :" & lt; HpWnd=GetParent (hWnd); 
Cout & lt; <"The parent window handle (from GetParent) :" & lt; TempHandle=GetWindowLongPtr (hWnd GWLP_HINSTANCE); 
If (tempHandle==0) 
{
DWORD errorCode=GetLastError (); 
Cout & lt; <"Get the instance handle the error:" & lt; } 
The else 
{
(HINSTANCE HINSTANCE hInst=* *) (& amp; TempHandle); 
Cout & lt; <"The instance handle:" & lt; } 
} 

Int main (int arg c, char * * argv) 
{
TestGetInstance (); 
} 

There is a problem, it is call GetParent (hWnd); And GetWindowLongPtr (hWnd, GWLP_HWNDPARENT); Obtain the handle to the parent window with Visual Studio 2017 of Spy++ tools see,
The great god, please advice, thank you!