HINSTANCE data type HINSTANCE data type

Reprinted: https://www.cnblogs.com/furzoom/p/hinstance.html

Author: Ma Yan ( Furzoom ) ( http://www.cnblogs.com/furzoom/ )
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在看《 WINDOWS程序设计》过程中，对于HINSTANCE的理解很重要，网上多数说其是一个整型变量，其实是不对的。http://furzoom.com/

HINSTANCE定义

HINSTANCE数据类型－枫竹梦

通过查找HINSTANCE的定义有WINDEF.H中为：

 
          DECLARE_HANDLE( 
          HINSTANCE 
          );

Guess it should be a macro definition, continue to look at the definition of DECLARE_HANDLE (), also in WINDEF.H, as follows:

 
          #ifdef STRICT 
         
          typedef 
          void 
          * 
          HANDLE 
          ; 
         
          #define DECLARE_HANDLE(name) struct name##__ { int unused; }; typedef struct name##__ *name 
         
          #else 
         
          typedef 
          PVOID 
          HANDLE 
          ; 
         
          #define DECLARE_HANDLE(name) typedef HANDLE name 
         
          #endif 
         
          typedef 
          HANDLE 
          * 
          PHANDLE 
          ;

It can be seen that DECLARE_HANDLE () is defined in a pre-defined condition, so whether the condition is true, continue to search for the definition of STRICT, at the beginning of WINDEF.H are as follows:

 
          #ifndef _WINDEF_ 
         
          #define _WINDEF_ 
         
          #ifndef NO_STRICT 
         
          #ifndef STRICT 
         
          #define STRICT 1 
         
          #endif 
         
          #endif /* NO_STRICT */

In this way, we know that STRICT is defined by default.

Then look at the definition of DECLARE_HANDLE () macro,

 
          #define DECLARE_HANDLE(name) struct name##__ { int unused; }; typedef struct name##__ *name

## is a character connection, then

 
          DECLARE_HANDLE( 
          HINSTANCE 
          )

Equivalent to

 
          struct 
          HINSTANCE__ {  
          int 
          unused; };  
          typedef 
          struct 
          HINSTANCE__ * 
          HINSTANCE 
          ;

HINSTANCE is a pointer variable that points to the HINSTANCE structure, and there is only one int variable in the structure. In WINDOWS, handles are mostly defined in this way.

From: HINSTANCE data type - WINDOWS programming - Maple Bamboo Dream