窗口句柄无效是什么原因???

ming6424 2004-12-09 10:35:13
运行程序时,弹出一个对话框,提示
xxxxxxxx指令引发的xxxxxxxx内存错误,该内存不能为read

HWND hwnd;
HDC hdc;
hwnd = CreateWindow(......);//执行完这步后,hwnd的值不是0xcccccccc


hdc = GetDC(hwnd);//这里又说参数1无效
...全文
467 6 打赏 收藏 转发到动态 举报
AI 作业
写回复
用AI写文章
6 条回复
切换为时间正序
请发表友善的回复…
发表回复
oyljerry 2004-12-09
  • 打赏
  • 举报
回复
IsWindow()
aoosang 2004-12-09
  • 打赏
  • 举报
回复
嗯,楼上的说得对头
koko1998 2004-12-09
  • 打赏
  • 举报
回复
你用的是CreateWindow,是不是你参数不对阿
在使用CreateWindow函数之前,得使用RegisterClass将该窗体注册。
参考msn:
The CreateWindow function creates an overlapped, pop-up, or child window. It specifies the window class, window title, window style, and (optionally) the initial position and size of the window. The function also specifies the window's parent or owner, if any, and the window's menu.

To use extended window styles in addition to the styles supported by CreateWindow, use the CreateWindowEx function.

HWND CreateWindow(
LPCTSTR lpClassName, // registered class name
LPCTSTR lpWindowName, // window name
DWORD dwStyle, // window style
int x, // horizontal position of window
int y, // vertical position of window
int nWidth, // window width
int nHeight, // window height
HWND hWndParent, // handle to parent or owner window
HMENU hMenu, // menu handle or child identifier
HINSTANCE hInstance, // handle to application instance
LPVOID lpParam // window-creation data
);
Parameters
lpClassName
[in] Pointer to a null-terminated string or a class atom created by a previous call to the RegisterClass or RegisterClassEx function. The atom must be in the low-order word of lpClassName; the high-order word must be zero.
If lpClassName is a string, it specifies the window class name. The class name can be any name registered with RegisterClass or RegisterClassEx, provided that the module that registers the class is also the module that creates the window. The class name can also be any of the predefined system class names. For a list of system class names, see the Remarks section.

lpWindowName
[in] Pointer to a null-terminated string that specifies the window name.
If the window style specifies a title bar, the window title pointed to by lpWindowName is displayed in the title bar. When using CreateWindow to create controls, such as buttons, check boxes, and static controls, use lpWindowName to specify the text of the control. When creating a static control with the SS_ICON style, use lpWindowName to specify the icon name or identifier. To specify an identifier, use the syntax "#num".

dwStyle
[in] Specifies the style of the window being created. This parameter can be a combination of window styles, plus the control styles indicated in the Remarks section.
x
[in] Specifies the initial horizontal position of the window. For an overlapped or pop-up window, the x parameter is the initial x-coordinate of the window's upper-left corner, in screen coordinates. For a child window, x is the x-coordinate of the upper-left corner of the window relative to the upper-left corner of the parent window's client area.
If this parameter is set to CW_USEDEFAULT, the system selects the default position for the window's upper-left corner and ignores the y parameter. CW_USEDEFAULT is valid only for overlapped windows; if it is specified for a pop-up or child window, the x and y parameters are set to zero.

y
[in] Specifies the initial vertical position of the window. For an overlapped or pop-up window, the y parameter is the initial y-coordinate of the window's upper-left corner, in screen coordinates. For a child window, y is the initial y-coordinate of the upper-left corner of the child window relative to the upper-left corner of the parent window's client area. For a list box, y is the initial y-coordinate of the upper-left corner of the list box's client area relative to the upper-left corner of the parent window's client area.
If an overlapped window is created with the WS_VISIBLE style bit set and the x parameter is set to CW_USEDEFAULT, the system ignores the y parameter.

nWidth
[in] Specifies the width, in device units, of the window. For overlapped windows, nWidth is either the window's width, in screen coordinates, or CW_USEDEFAULT. If nWidth is CW_USEDEFAULT, the system selects a default width and height for the window; the default width extends from the initial x-coordinate to the right edge of the screen, and the default height extends from the initial y-coordinate to the top of the icon area. CW_USEDEFAULT is valid only for overlapped windows; if CW_USEDEFAULT is specified for a pop-up or child window, nWidth and nHeight are set to zero.
nHeight
[in] Specifies the height, in device units, of the window. For overlapped windows, nHeight is the window's height, in screen coordinates. If nWidth is set to CW_USEDEFAULT, the system ignores nHeight.
hWndParent
[in] Handle to the parent or owner window of the window being created. To create a child window or an owned window, supply a valid window handle. This parameter is optional for pop-up windows.
Windows 2000/XP: To create a message-only window, supply HWND_MESSAGE or a handle to an existing message-only window.

hMenu
[in] Handle to a menu, or specifies a child-window identifier depending on the window style. For an overlapped or pop-up window, hMenu identifies the menu to be used with the window; it can be NULL if the class menu is to be used. For a child window, hMenu specifies the child-window identifier, an integer value used by a dialog box control to notify its parent about events. The application determines the child-window identifier; it must be unique for all child windows with the same parent window.
hInstance
Windows 95/98/Me: [in] Handle to the instance of the module to be associated with the window.
Windows NT/2000/XP: This value is ignored.

lpParam
[in] Pointer to a value to be passed to the window through the CREATESTRUCT structure passed in the lParam parameter the WM_CREATE message. If an application calls CreateWindow to create a multiple document interface (MDI) client window, lpParam must point to a CLIENTCREATESTRUCT structure.
koko1998 2004-12-09
  • 打赏
  • 举报
回复
这个hwnd是不是0x00000000亚
张佩 2004-12-09
  • 打赏
  • 举报
回复
大概你的hwnd = CreateWindow(......);错了。返回一个错误的hwnd。
还有,你能保证hdc = GetDC(hwnd);的时候,hwnd没有被销毁吗?
bohut 2004-12-09
  • 打赏
  • 举报
回复
if(::IsWindow(hwnd))
hdc = GetDC(hwnd);

16,548

社区成员

发帖
与我相关
我的任务
社区描述
VC/MFC相关问题讨论
社区管理员
  • 基础类社区
  • AIGC Browser
  • encoderlee
加入社区
  • 近7日
  • 近30日
  • 至今
社区公告

        VC/MFC社区版块或许是CSDN最“古老”的版块了,记忆之中,与CSDN的年龄几乎差不多。随着时间的推移,MFC技术渐渐的偏离了开发主流,若干年之后的今天,当我们面对着微软的这个经典之笔,内心充满着敬意,那些曾经的记忆,可以说代表着二十年前曾经的辉煌……
        向经典致敬,或许是老一代程序员内心里面难以释怀的感受。互联网大行其道的今天,我们期待着MFC技术能够恢复其曾经的辉煌,或许这个期待会永远成为一种“梦想”,或许一切皆有可能……
        我们希望这个版块可以很好的适配Web时代,期待更好的互联网技术能够使得MFC技术框架得以重现活力,……

试试用AI创作助手写篇文章吧