DLL中未定义的函数指针 [英] Undefined function pointer in DLL

问题描述

您好。我的问题是我得到标识符是未定义的问题，尽管定义它。这是情况的背景：

 ... 
  typedef  WINSETUPAPI BOOL（* SetupDiEnumDeviceInterfacesUMPTR）（HDEVINFO，PSP_DEVINFO_DATA，LPGUID，DWORD，PSP_DEVICE_INTERFACE_DATA）; 
 ... 
  class  DLL 
 {
  public ：
 DLL（）
 {
 ... 
 SetupDiEnumDeviceInterfacesUMPTR _SetupDiEnumDeviceInterfacesUMPTR; 
 ... 
 HINSTANCE hSetUpApi = LoadLibrary（  setupapi.dll） ; 
 ... 
 _SetupDiEnumDeviceInterfacesUMPTR =（SetupDiEnumDeviceInterfacesUMPTR）GetProcAddress（hSetUpApi，  SetupDiEnumDeviceInterfaces）; 
 ... 
} 
 ... 
  if （_ SetupDiEnumDeviceInterfacesUMPTR（DeviceInfoTable，NULL，& InterfaceClassGuid，InterfaceIndex） ，InterfaceDataStructure）） //   _SetupDiEnumDeviceInterfacesUMPTR undefined  
 ... 
} 

感谢您的帮助。

解决方案

_SetupDiEnumDeviceInterfacesUMPTR <当你到达if语句时，/ code>超出了范围 - 它是在 DLL（）的大括号内定义的



此处说明...

http：// www.tutorialspoint.com/cplusplus/cpp_variable_scope.htm [ ^ ]

Hello. My problem is i get identifier is undefined problem despite defining it. Here''s the context of the situation:

...
typedef WINSETUPAPI BOOL (*SetupDiEnumDeviceInterfacesUMPTR)(HDEVINFO, PSP_DEVINFO_DATA, LPGUID, DWORD, PSP_DEVICE_INTERFACE_DATA);
...
class DLL
{ 
  public:
         DLL()
         {
             ...
             SetupDiEnumDeviceInterfacesUMPTR _SetupDiEnumDeviceInterfacesUMPTR;
             ...
             HINSTANCE hSetUpApi = LoadLibrary("setupapi.dll");
             ...
             _SetupDiEnumDeviceInterfacesUMPTR = (SetupDiEnumDeviceInterfacesUMPTR)GetProcAddress(hSetUpApi, "SetupDiEnumDeviceInterfaces");
             ...
         }
         ...
         if(_SetupDiEnumDeviceInterfacesUMPTR(DeviceInfoTable, NULL, &InterfaceClassGuid, InterfaceIndex, InterfaceDataStructure)) // _SetupDiEnumDeviceInterfacesUMPTR undefined
         ...
}

Thanks for help.

解决方案

_SetupDiEnumDeviceInterfacesUMPTR is out of scope by the time you get to the if statement - it''s defined inside the braces of DLL()

Explanation here ...
http://www.tutorialspoint.com/cplusplus/cpp_variable_scope.htm[^]

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