C語言編寫dll並調用

dll.h文件

#ifndef _DLL_H_
#define _DLL_H_

#if BUILDING_DLL
#define DLLIMPORT __declspec(dllexport)
#else
#define DLLIMPORT __declspec(dllimport)
#endif

DLLIMPORT int add(int i,int j);

#endif

dll.c文件

/* Replace "dll.h" with the name of your header */
#include "dll.h"
#include <windows.h>

DLLIMPORT int add(int i, int j)
{
    return i+j;
}

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason,LPVOID lpvReserved)
{
    switch(fdwReason)
    {
        case DLL_PROCESS_ATTACH:
        {
            break;
        }
        case DLL_PROCESS_DETACH:
        {
            break;
        }
        case DLL_THREAD_ATTACH:
        {
            break;
        }
        case DLL_THREAD_DETACH:
        {
            break;
        }
    }
    
    /* Return TRUE on success, FALSE on failure */
    return TRUE;
}

exe.c文件（調用dll的）

#include <windows.h>
#include <stdio.h>
 
typedef int (*Fun)(int,int);     //這里聲明一個函數指針，typedef 關鍵字是必須的，好像要顯示調用dll中的函數，都需要這樣用函數指針給出聲明
 
int main()
{
    HINSTANCE hDll;
    Fun Add;
    hDll=LoadLibrary("myDll.dll");
    if (hDll==NULL)
    {
        printf("%s","failed to load dll!\n");
    }
    else
    {
        printf("%s","succeeded in loading dll\n");
        Add=(Fun)GetProcAddress(hDll,"add");
        if (Add!=NULL)
        {
            int i,j;
            printf("%s","input the first number:");
            scanf("%d",&i);
            printf("%s","input the first number:");
            scanf("%d",&j);
            printf("sum = %d\n",Add(i,j));
        }
    }
    FreeLibrary(hDll);
    
    system("pause");
    return 0;
}