Linking Explicitly
The latest version of this topic can be found at Linking Explicitly.
With explicit linking, applications must make a function call to explicitly load the DLL at run time. To explicitly link to a DLL, an application must:
Call LoadLibrary (or a similar function) to load the DLL and obtain a module handle.
Call GetProcAddress to obtain a function pointer to each exported function that the application wants to call. Because applications are calling the DLL's functions through a pointer, the compiler does not generate external references, so there is no need to link with an import library.
Call FreeLibrary when done with the DLL.
For example:
typedef UINT (CALLBACK* LPFNDLLFUNC1)(DWORD,UINT);
...
HINSTANCE hDLL; // Handle to DLL
LPFNDLLFUNC1 lpfnDllFunc1; // Function pointer
DWORD dwParam1;
UINT uParam2, uReturnVal;
hDLL = LoadLibrary("MyDLL");
if (hDLL != NULL)
{
lpfnDllFunc1 = (LPFNDLLFUNC1)GetProcAddress(hDLL,
"DLLFunc1");
if (!lpfnDllFunc1)
{
// handle the error
FreeLibrary(hDLL);
return SOME_ERROR_CODE;
}
else
{
// call the function
uReturnVal = lpfnDllFunc1(dwParam1, uParam2);
}
}