Question

How can I use the functions in a DLL in C without a LIB file to go with it? I know all of the function prototypes and their names.

Answer 1

Yes you can. You should use the GetProcAddress function, to call the function directly in the DLL, without involving the LIB

Processes explicitly linking to a DLL call GetProcAddress to obtain
the address of an exported function in the DLL. You use the returned
function pointer to call the DLL function.

To quote the Example from the above link:

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);
   }
}