未定義的參考`的WindowProc（HWND __ *，無符號整型，無符號整型，長）@ 16'

我不斷收到以下錯誤，當我嘗試編譯我非常簡單的程序：未定義的參考`的WindowProc（HWND __ *，無符號整型，無符號整型，長）@ 16'

未定義引用的WindowProc（ HWND __ *，unsigned int，unsigned int，long）@ 16'

我沒有看到問題，它讓我瘋狂！

#include <iostream> 
#include <windows.h> 

using namespace std; 

int sizeX = 500; 
int sizeY = 500; 

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam); 

char szClassName[ ] = "WindowsApp"; 

int WINAPI WinMain(
        HINSTANCE hThisInstance, 
        HINSTANCE hPrevInstance, 
        LPSTR lpszArgument, 
        int nFunsterStil 
        ) 
{ 
    HWND hwnd; 
    MSG messages; 
    WNDCLASSEX wincl; 

    wincl.hInstance = hThisInstance; 
    wincl.lpszClassName = szClassName; 
    wincl.lpfnWndProc = WindowProc; 
    wincl.style = CS_DBLCLKS; 
    wincl.cbSize = sizeof(WNDCLASSEX);` 

    wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION); 
    wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION); 
    wincl.hCursor = LoadCursor(NULL, IDC_ARROW); 
    wincl.lpszMenuName = NULL; 
    wincl.cbClsExtra = 0; 
    wincl.cbWndExtra = 0; 

    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND; 

    if(!RegisterClassEx(&wincl)) 
     return 0; 

    hwnd = CreateWindowEx(
          0, 
          szClassName, 
          "Windows App", 
          WS_SYSMENU, 
          CW_USEDEFAULT, 
          CW_USEDEFAULT, 
          sizeX, 
          sizeY, 
          HWND_DESKTOP, 
          NULL, 
          hThisInstance, 
          NULL 
        ); 
}

代碼有什麼問題？

來源

2017-04-21 Diriector_Doc

哪裏是'WindowProc'？你宣佈它，但實際功能在哪裏？ – PaulMcKenzie

您沒有提供WindowProc()的定義。你宣佈它，並將其分配給您的WNDCLASSEX，現在你必須真正實現它的身體，如：

#include <iostream> 
#include <windows.h> 

using namespace std; 

int sizeX = 500; 
int sizeY = 500; 

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam); 

const char szClassName[ ] = "WindowsApp"; 

int WINAPI WinMain(
        HINSTANCE hThisInstance, 
        HINSTANCE hPrevInstance, 
        LPSTR lpszArgument, 
        int nFunsterStil 
        ) 
{ 
    HWND hwnd; 
    MSG messages; 
    WNDCLASSEX wincl; 

    wincl.hInstance = hThisInstance; 
    wincl.lpszClassName = szClassName; 
    wincl.lpfnWndProc = WindowProc; 
    wincl.style = CS_DBLCLKS; 
    wincl.cbSize = sizeof(WNDCLASSEX);` 

    wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION); 
    wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION); 
    wincl.hCursor = LoadCursor(NULL, IDC_ARROW); 
    wincl.lpszMenuName = NULL; 
    wincl.cbClsExtra = 0; 
    wincl.cbWndExtra = 0; 

    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND; 

    if(!RegisterClassEx(&wincl)) 
     return 0; 

    hwnd = CreateWindowEx(
          0, 
          szClassName, 
          "Windows App", 
          WS_SYSMENU, 
          CW_USEDEFAULT, 
          CW_USEDEFAULT, 
          sizeX, 
          sizeY, 
          HWND_DESKTOP, 
          NULL, 
          hThisInstance, 
          NULL 
        ); 

    // message loop here ... 

    return 0; 
} 

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) 
{ 
    // your code here ... 

    return DefWindowProc(hwnd, uMsg, wParam, lParam); 
}

查看MSDN文檔以獲取更多詳細信息：

Window Procedures

來源

2017-04-21 22:26:51

未定義的參考`的WindowProc（HWND __ *，無符號整型，無符號整型，長）@ 16'

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