问题描述
- win32编程中窗口不显示是什么问题
-
《windows程序设计》第9章ENVIRON程序
把光盘中的源代码粘贴出来发现还是没有窗口在运行,实在想不明白
(运行环境:VS2013,WINDOWS7)
以下源代码:#include
#define ID_LIST 1
#define ID_TEXT 2LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("Environ") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("Environment List Box"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ;
}
void FillListBox (HWND hwndList)
{
int iLength ;
TCHAR * pVarBlock, * pVarBeg, * pVarEnd, * pVarName ;pVarBlock = GetEnvironmentStrings () ; // Get pointer to environment block while (*pVarBlock) { if (*pVarBlock != '=') // Skip variable names beginning with '=' { pVarBeg = pVarBlock ; // Beginning of variable name while (*pVarBlock++ != '=') ; // Scan until '=' pVarEnd = pVarBlock - 1 ; // Points to '=' sign iLength = pVarEnd - pVarBeg ; // Length of variable name // Allocate memory for the variable name and terminating // zero. Copy the variable name and append a zero. pVarName = calloc (iLength + 1, sizeof (TCHAR)) ; CopyMemory (pVarName, pVarBeg, iLength * sizeof (TCHAR)) ; pVarName[iLength] = '' ; // Put the variable name in the list box and free memory. SendMessage (hwndList, LB_ADDSTRING, 0, (LPARAM) pVarName) ; free (pVarName) ; } while (*pVarBlock++ != '') ; // Scan until terminating zero } FreeEnvironmentStrings (pVarBlock) ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static HWND hwndList, hwndText ;
int iIndex, iLength, cxChar, cyChar ;
TCHAR * pVarName, * pVarValue ;switch (message) { case WM_CREATE : cxChar = LOWORD (GetDialogBaseUnits ()) ; cyChar = HIWORD (GetDialogBaseUnits ()) ; // Create listbox and static text windows. hwndList = CreateWindow (TEXT ("listbox"), NULL, WS_CHILD | WS_VISIBLE | LBS_STANDARD, cxChar, cyChar * 3, cxChar * 16 + GetSystemMetrics (SM_CXVSCROLL), cyChar * 5, hwnd, (HMENU) ID_LIST, (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE), NULL) ; hwndText = CreateWindow (TEXT ("static"), NULL, WS_CHILD | WS_VISIBLE | SS_LEFT, cxChar, cyChar, GetSystemMetrics (SM_CXSCREEN), cyChar, hwnd, (HMENU) ID_TEXT, (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE), NULL) ; FillListBox (hwndList) ; return 0 ; case WM_SETFOCUS : SetFocus (hwndList) ; return 0 ; case WM_COMMAND : if (LOWORD (wParam) == ID_LIST && HIWORD (wParam) == LBN_SELCHANGE) { // Get current selection. iIndex = SendMessage (hwndList, LB_GETCURSEL, 0, 0) ; iLength = SendMessage (hwndList, LB_GETTEXTLEN, iIndex, 0) + 1 ; pVarName = calloc (iLength, sizeof (TCHAR)) ; SendMessage (hwndList, LB_GETTEXT, iIndex, (LPARAM) pVarName) ; // Get environment string. iLength = GetEnvironmentVariable (pVarName, NULL, 0) ; pVarValue = calloc (iLength, sizeof (TCHAR)) ; GetEnvironmentVariable (pVarName, pVarValue, iLength) ; // Show it in window. SetWindowText (hwndText, pVarValue) ; free (pVarName) ; free (pVarValue) ; } return 0 ; case WM_DESTROY : PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ;
解决方案
估计窗口没有创建成功等,失败了,你可以设置断点跟踪一下,看你的代码在哪里出错了
解决方案二:
CreateWindow后,看一下是否取得hWnd。如果hWnd==INVALID_HANDLE_VALUE(或者NULL),要去做GetLastError()获取错误原因。根据LastError分析原因
解决方案三:
你的程序用了好几个资源,比如图标、光标字符串,这些资源你都附加到程序里了么?还是你只是复制粘贴了程序。
解决方案四:
转换函数calloc 的返回指针类型后编译通过,并出现界面。
编译环境:
vs2012 WINDOWS8.1