收到错误，即"unresolved external symbol"

我刚刚开始学习DirectX，我正在尝试使用C++语言来实现它。我已经开始阅读一本关于这个问题的书，名为《Beginning DirectX 10 Game Programming》。没关系，我遇到了一个问题。我已经添加了所需的库，并在Visual Studio中包含了必要的文件。错误如下：

Error   26  error LNK2019: unresolved external symbol "bool __cdecl InitDirect3D(struct HWND__ *,int,int)" (?InitDirect3D@@YA_NPAUHWND__@@HH@Z) referenced in function _WinMain@16  C:UsersRobertdocumentsvisual studio 2013ProjectsDirectXBookexampleWithDirectX1SourceCode.obj    exampleWithDirectX1
Error   27  error LNK1120: 1 unresolved externals   C:UsersRobertdocumentsvisual studio 2013ProjectsDirectXBookDebugexampleWithDirectX1.exe 1   1   exampleWithDirectX1
#include <Windows.h>
#include <tchar.h>
#include <d3d10.h>
#include <d3dx10.h>
#pragma comment (lib, "d3dx10.lib")
#pragma comment (lib, "d3d10.lib")
HINSTANCE hInstance;        //Instanszkezelo
HWND hWnd;                  //Ablakkezelo
ID3D10Device *pD3DDevice = NULL;
IDXGISwapChain *pSwapChain = NULL;
ID3D10RenderTargetView *pRenderTargetView = NULL;
int width = 640;
int height = 480;
//fuggveny prototipusok definialasa
bool InitWindow(HINSTANCE hInstance, int width, int height);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
bool InitDirect3D(HWND hWnd, int width, int height);
void Render();
void shutDownDirect3D();
//WinMain, belepopont a windows applikacioba
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdline, int nCmdShow){
    //ablakinicalizalas
    if (!InitWindow(hInstance, width, height)){
        return false;
    }
    if (!InitDirect3D(hWnd, width, height)){
        return 0;
    }
    //main message loop
    MSG msg = { 0 };
    while (WM_QUIT != msg.message){
        while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) == TRUE){
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        //renderelest kezelo fuggveny meghivasa
        Render();
    }
    shutDownDirect3D();
    return msg.wParam;
}
bool InitWindow(HINSTANCE hInstance, int width, int height){
    WNDCLASSEX wcex;
    // WNDCLASSEX wcex objektum kitoltese
    // meghatarozza, hogyan fog kinezni az ablakunk
    wcex.cbSize = sizeof(WNDCLASSEX); // struktura merete
    wcex.style = CS_HREDRAW | CS_VREDRAW; // az osztaly tipusa
    wcex.lpfnWndProc = (WNDPROC)WndProc; // az ablak procedure visszahivas (callback)
    wcex.cbClsExtra = 0; // extra byteok lefoglasasa az osztalynak
    wcex.cbWndExtra = 0; // extra bytes to allocate for this instance
    wcex.hInstance = hInstance; // kezelo az applikacios esemenynek
    wcex.hIcon = 0; // applikaciohoz hozzarendelendo ikon
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW); // kurzor hasznalatanak definialasa
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1); // hatterszin
    wcex.lpszMenuName = NULL; // eroforrsanev a menunek
    wcex.lpszClassName = TEXT("DirectXExample"); // az osztalynev letrehozva
    wcex.hIconSm = 0; // kezelo a kisikonhoz
    RegisterClassEx(&wcex);     //wcex objektum regisztralasa
    RECT rect = { 0, 0, width, height }; // ablakatmeretezes
    AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, FALSE);
    // ablak letrehozasa a felso osztalybol
    hWnd = CreateWindow(TEXT("DirectXExample"),
        TEXT("DirectXExample"),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        rect.right - rect.left,
        rect.bottom - rect.top,
        NULL,
        NULL,
        hInstance,
        NULL);
    if (!hWnd){
        return false;
    }
    // ablak kirajzoalsa a kijelzore
    ShowWindow(hWnd, SW_SHOW);
    UpdateWindow(hWnd);
    return true;
}
//WPARAM == typedef UINT_PTR WPARAM passing and returning polymorphic values
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){
    //megnézi, hogy van - e üzenet a sorban
    switch (message){
    case WM_KEYDOWN:
        switch (wParam){
            //ha a felhasznalo az escape billentyu megnyomja kilepes
        case VK_ESCAPE:
            PostQuitMessage(0);
            break;
        }
        //ha a felhasznalo az X gombra kattint kilepes
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    }
    //uzenet elkuldese az alapveto ablak proceduranak, hogy az tovabb elemezze
    return DefWindowProc(hWnd, message, wParam, lParam);
}
bool InitDirect3d(HWND hWnd, int width, int height){
    // Create and clear the DXGI_SWAP_CHAIN_DESC structure
    DXGI_SWAP_CHAIN_DESC swapChainDesc;
    ZeroMemory(&swapChainDesc, sizeof(swapChainDesc));
    // Fill in the needed values
    swapChainDesc.BufferCount = 1;
    swapChainDesc.BufferDesc.Width = width;
    swapChainDesc.BufferDesc.Height = height;
    swapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    swapChainDesc.BufferDesc.RefreshRate.Numerator = 60;
    swapChainDesc.BufferDesc.RefreshRate.Denominator = 1;
    swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    swapChainDesc.OutputWindow = hWnd;
    swapChainDesc.SampleDesc.Count = 1;
    swapChainDesc.SampleDesc.Quality = 0;
    swapChainDesc.Windowed = TRUE;
    // Create the D3D device and the swap chain
    HRESULT hr = D3D10CreateDeviceAndSwapChain(NULL,
        D3D10_DRIVER_TYPE_REFERENCE,
        NULL,
        0,
        D3D10_SDK_VERSION,
        &swapChainDesc,
        &pSwapChain,
        &pD3DDevice);
    // Error checking. Make sure the device was created
    if (hr != S_OK){
        return false;
    }
    // Get the back buffer from the swapchain
    ID3D10Texture2D *pBackBuffer;
    hr = pSwapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (LPVOID*)
        &pBackBuffer);
    if (hr != S_OK){
        return false;
    }
    // create the render target view
    hr = pD3DDevice->CreateRenderTargetView(pBackBuffer, NULL, &pRenderTargetView);
    // release the back buffer
    pBackBuffer->Release();
    // Make sure the render target view was created successfully
    if (hr != S_OK){
        return false;
    }
    // set the render target
    pD3DDevice->OMSetRenderTargets(1, &pRenderTargetView, NULL);
    // create and set the viewport
    D3D10_VIEWPORT viewPort;
    viewPort.Width = width;
    viewPort.Height = height;
    viewPort.MinDepth = 0.0f;
    viewPort.MaxDepth = 1.0f;
    viewPort.TopLeftX = 0;
    viewPort.TopLeftY = 0;
    pD3DDevice->RSSetViewports(1, &viewPort);
    return true;
}
void Render(){
    if (pD3DDevice != NULL){
        //a celpuffer tisztitasa
        pD3DDevice->ClearRenderTargetView(pRenderTargetView, D3DXCOLOR(0.0f, 0.0f, 0.0f, 0.0f));
        //IDE JON A RAJZOLAS
        //a kovetkezo elem kijelzese a SwapChain - bol
        pSwapChain->Present(0, 0);
    }
}
void shutDownDirect3D(){
    //release the rendertarget
    if (pRenderTargetView){
        pRenderTargetView->Release();
    }
    if (pSwapChain){
        pSwapChain->Release();
    }
    if (pD3DDevice){
        pD3DDevice->Release();
    }
}

提前感谢！