C ++ Dynamic Link Library

Dynamic Link Library

I

1. dll

. H file

# Ifdef dll.pdf API
# Else
# Define Dllsort api _ declspec (dllimport)
# Endif
Dll.pdf API Int Add ( Int A, Int B );
Dll.pdf API Int Sub ( Int A, Int B );
Class Dllw.api point
{
Public :
Void Output ( Int X, Int Y );
};

 

. Cpp File

# Define Dllsort api _ declspec (dllimport)
# Include " Dll1.h "
# Include <windows. h>
# Include <stdio. h>
Int Add ( Int A, Int B)
{
Return A + B;
}
Int Sub ( Int A, Int B)
{
Return A-B;
}
Void Point: output ( Int X, Int Y)
{
Hwnd;
Hwnd = getforegroundwindow ();
HDC = getdc (hwnd );
Char Buf [ 20 ];
Memset (BUF, 0 , 20 );
Sprintf (BUF, " X = % d, y = % d " , X, y );
Textout (HDC, 0 , 0 , Buf, strlen (BUF ));
Releasedc (hwnd, HDC );

}

Call DLL to put the compiled. dll and. Lib files inProgramDirectory to copy the. h file of the DLL to the directory of the referenced program. Project-> setting-> link: Set the Lib File Location of the Object/library modules. For example, "Debug/dll3.lib ".

Add Referenced File # include "dll1.h"

Void Cdlltestdlg: onbtnadd ()
{
// Todo: add your control notification handler code here
Cstring STR;
Str. Format ( " 5 + 3 = % d " , Add ( 5 , 3 ));
MessageBox (STR );
}

void cdlltestdlg: onbtnsub ()
{< br> // todo: add your control notification handler code here
cstring STR;
Str. format ( " 5-3 = % d " , sub ( 5 , 3 );
MessageBox (STR );
}

VoidCdlltestdlg: onbtnoutput ()
{
//Todo: add your control notification handler code here
Point pt;
PT. Output (5,3);
}

II. The def method solves the name adaptation problem and uses different languages.

Create a new file with the extension name def in the program directory and add it to the project in project-> Add to project \ files.

DLL

. Def

Library dll3
Exports
Add

. Cpp

 

Int _ stdcall add (int A, int B)
{
Return A + B;
}

Call

. H

 

_ Declspec (dllimport) Int _ Stdcall add ( Int A, Int B );

. Cpp

Void Cdll3testdlg: onbtnadd ()
{
Cstring STR;
Str. Format ( " 5 + 3 = % d " , Add ( 5 , 3 ));
MessageBox (STR );
}

 

All of the preceding call methods are implicitly linked to achieve dynamic link library access.

Dynamic Loading Mode

Void Cdll3testdlg: onbtnadd ()
{
Hinstance hinst; // DLL handle
Hinst = loadlibrary ( " Dll3.dll " ); // Dynamic DLL Loading
Typedef Int (_ Stdcall * lpadd )( Int , Int ); // Define function pointer type
Lpadd addfun = (lpadd) getprocaddress (hinst, " Add " );
If (! Addfun)
{
MessageBox ( " An error occurred while obtaining the function address! " );
Return ;
}
Cstring STR;
Str. Format ( " 5 + 3 = % d " , Addfun ( 5 , 3 ));
Freelibrary (hinst ); // No need to access DLL, release
MessageBox (STR );
}

 

Summary. Def can solve cross-language problems, which is favored by individuals. Please leave a message. You are learning C ++.