无法在C++Win32中将URL或ID设置为SysLink

Can not Set URL or ID to SysLink in C++ Win32

本文关键字：ID 设置 SysLink URL C++Win32 中将      更新时间：2023-10-16

这是我的代码，但它没有编译，并给出两个错误：

error C2440: '=' : cannot convert from 'WCHAR' to 'WCHAR [2084]'     
IntelliSense: expression must be a modifiable lvalue

我已经阅读了下面的链接，但它对我没有帮助：

错误C2106:'='；：左操作数必须是l值

[代码]：

#define ID_SysLink 500              
HWND hWnd;
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
switch (Msg)
{
case WM_CREATE:
    {
        HWND syslink_handle=0;
        syslink_handle=CreateWindowEx(0, WC_LINK, L"test syslink",  WS_VISIBLE | WS_CHILD , 10, 10, 100, 30, hWnd, HMENU(ID_SysLink), 0, 0);
        LITEM *pitem = 0;
        pitem->iLink = 0; 
        pitem->mask = LIF_ITEMINDEX | LIF_ITEMID | LIF_URL | LIF_STATE;
        pitem->state = LIS_ENABLED | LIS_FOCUSED | LIS_HOTTRACK;
        pitem->stateMask = LIS_ENABLED | LIS_FOCUSED | LIS_HOTTRACK;
        WCHAR url_wchar = WCHAR(L"http://www.google.com");
        pitem->szUrl = url_wchar;
        SendMessage(syslink_handle, LM_SETITEM, 0, LPARAM(&pitem));
    }
    break;
case WM_CLOSE:
    DestroyWindow(hWnd);
    break;
case WM_DESTROY:
    PostQuitMessage(0);
    break;
default:
    return DefWindowProc(hWnd, Msg, wParam, lParam);
    break;
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance , HINSTANCE hPreviewInstance,LPSTR lpcmdline,int ncmdshow)
{
   WNDCLASSEX wndexcls;
   wndexcls.lpszClassName = wndclssname;
   wndexcls.hIcon = LoadIcon(NULL, IDI_APPLICATION);
   wndexcls.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
   wndexcls.hCursor = LoadCursor(NULL, IDC_ARROW);
   wndexcls.hbrBackground = (HBRUSH)(COLOR_3DDKSHADOW + 1);
   wndexcls.lpszMenuName = NULL;
   wndexcls.style = NULL;
   wndexcls.hInstance = hInstance;
   wndexcls.cbSize = sizeof(WNDCLASSEX);
   wndexcls.cbClsExtra = 0;
   wndexcls.cbWndExtra = 0;
   wndexcls.lpfnWndProc = WndProc;
   RegisterClassEx(&wndexcls);
   hWnd = CreateWindowEx(WS_EX_CLIENTEDGE, L"winclass", L"TestApp", WS_OVERLAPPEDWINDOW, 100, 100, 640, 380, 0, 0,hInstance, 0);
   ShowWindow(hWnd, ncmdshow);
   UpdateWindow(hWnd);
   MSG wnd_msg;
   while (GetMessage(&wnd_msg,NULL,0,0)>0)
   {
    TranslateMessage(&wnd_msg);
    DispatchMessage(&wnd_msg);
   }
   return (int)wnd_msg.wParam;
 }

谢谢你的帮助。

   WCHAR url_wchar = WCHAR(L"http://www.google.com");
   pitem->szUrl = url_wchar;

你可能想让url_wchar成为一个指针：

    WCHAR* url_wchar = L"http://www.google.com";

不幸的是，szUrl不是指针，而是一个字符数组。因此，要分配它，您需要使用字符串复制函数将字符串复制到其中（而不仅仅是将其分配为指针）。例如，

    wcscpy_s(pitem->szUrl, L_MAX_URL_LENGTH, L"http://www.google.com");

如果你真的编译了这个，你会发现它或多或少会立即崩溃，因为这一点：

    LITEM *pitem = 0;
    pitem->iLink = 0;

你正在写入一个空指针。您需要为LITEM结构分配空间，或者（最好）在堆栈上声明它：

    LITEM item{};
    item.mask = LIF_ITEMINDEX | LIF_ITEMID | LIF_URL | LIF_STATE;
    item.state = LIS_ENABLED | LIS_FOCUSED | LIS_HOTTRACK;
    item.stateMask = LIS_ENABLED | LIS_FOCUSED | LIS_HOTTRACK;
    wcscpy_s(item.szUrl, L_MAX_URL_LENGTH, L"http://www.google.com");
    SendMessage(syslink_handle, LM_SETITEM, 0, (LPARAM)&item);
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