LIST BOX 的使用 无法显示环境变量 请各位给指点下

Question

#include <windows.h>
#include "resource.h"#define ID_LIST 1
#define ID_TEXT 2LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
void fillList(HWND);int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd){
static TCHAR szAppName[]=TEXT("ListBox");
HWND hwnd;
MSG msg;
WNDCLASS wndclass; wndclass.cbClsExtra=0;
wndclass.cbWndExtra=0;
wndclass.lpfnWndProc=WndProc;
wndclass.hbrBackground=(HBRUSH)(COLOR_WINDOW+1);
wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
wndclass.hIcon=LoadIcon(hInstance,MAKEINTRESOURCE(EDIT));
wndclass.hInstance=hInstance;
wndclass.lpszClassName=szAppName;
wndclass.lpszMenuName=NULL;
wndclass.style=CS_HREDRAW|CS_VREDRAW; if(!RegisterClass(&wndclass)){
MessageBox(NULL,TEXT("This program requires Windows NT!"),szAppName,MB_ICONERROR);
return 0;
} hwnd=CreateWindow(szAppName,TEXT("ListBox"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,CW_USEDEFAULT,
CW_USEDEFAULT,CW_USEDEFAULT,
NULL,NULL,hInstance,NULL); ShowWindow(hwnd,nShowCmd);
UpdateWindow(hwnd); while(GetMessage(&msg,NULL,NULL,NULL)){
TranslateMessage(&msg);
DispatchMessage(&msg);
} return msg.wParam;
}void fillList(HWND hwndList){
int iLength;
TCHAR *pVarBlock,*pVarBeg,*pVarEnd,*pVarName; pVarBlock=GetEnvironmentStrings();

if(pVarBlock==NULL){
MessageBox(NULL,TEXT("Function Error!"),TEXT("ERROR"),MB_ICONERROR);
return ;
} while(*pVarBlock){
if(*pVarBlock!='='){
pVarBeg=pVarBlock;
while(*pVarBlock++!='=') ;
pVarEnd=pVarBlock-1;
iLength=pVarEnd-pVarBeg;
pVarName=(TCHAR*)calloc(iLength+1,sizeof(TCHAR));
CopyMemory(pVarName,pVarBeg,iLength*sizeof(TCHAR));
pVarName[iLength]='\0';
SendMessage(hwndList,LB_ADDSTRING,0,(LPARAM)pVarName);
free(pVarName);
}
while(*pVarBlock++!='\0') ;
}
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()); hwndList=CreateWindow(TEXT("listbox"),NULL,
WS_CHILD|WS_VISIBLE|LBS_STANDARD,
cxChar,cyChar*3,
cxChar*32+GetSystemMetrics(SM_CXVSCROLL),
cyChar*10,
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); fillList(hwndList);
return 0; case WM_SETFOCUS:
SetFocus(hwndList);
return 0; case WM_COMMAND:
if(LOWORD(wParam)==ID_LIST&&HIWORD(wParam)==LBN_SELCHANGE){
iIndex=SendMessage(hwndList,LB_GETCURSEL,0,0);
iLength=SendMessage(hwndList,LB_GETTEXTLEN,iIndex,0)+1;
pVarName=(TCHAR*)calloc(iLength,sizeof(TCHAR));
SendMessage(hwndList,LB_GETTEXT,iIndex,(LPARAM)pVarName); iLength=GetEnvironmentVariable(pVarName,NULL,0);
pVarValue=(TCHAR*)calloc(iLength,sizeof(TCHAR));
GetEnvironmentVariable(pVarName,pVarValue,iLength); SetWindowText(hwndText,pVarValue);
free(pVarName);
free(pVarValue);
}
return 0; case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd,message,wParam,lParam);
}

Answer 1

确实很奇怪，我调了好久也没有找出原因；不过你可以换用ComboBox，在ComboBox下测试是没有问题的，编译我之后贴的源代码就可以看到，其实它的效果和ListBox是差不多的。之前先说下你代码的一个问题：
           hwndList=CreateWindow(TEXT("listbox"),NULL,
                WS_CHILD|WS_VISIBLE|LBS_STANDARD,
                cxChar,cyChar*3,
                cxChar*32+GetSystemMetrics(SM_CXVSCROLL),
                cyChar*10,
                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);
//CreateWindow是会触发WM_CREATE消息的，所以不能放在回调函数里做，这样的话每一次执行到CreateWindow都会发送WM_CREATE消息给窗口，这样窗口又会从case WM_CREATE:这里开始执行，
于是造成了递归的效果，这就是为什么你的ListBox的创建出来一层套一层的原因。
我把他们都转移到主窗口的创建的后面，也就是主窗口ShowWindow之前去执行了。代码：
#include <windows.h>#define ID_LIST 1
#define ID_TEXT 2LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);void fillList(HWND);    static HWND hwndList,hwndText;int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd){
    static TCHAR szAppName[]=TEXT("ListBox");
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;
    wndclass.lpfnWndProc=WndProc;
    wndclass.hbrBackground=(HBRUSH)(COLOR_WINDOW+1);
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndclass.hIcon=LoadIcon(NULL,IDI_ERROR);
    wndclass.hInstance=hInstance;
    wndclass.lpszClassName=szAppName;
    wndclass.lpszMenuName=NULL;
    wndclass.style=CS_HREDRAW|CS_VREDRAW;    if(!RegisterClass(&wndclass)){
        MessageBox(NULL,TEXT("This program requires Windows NT!"),szAppName,MB_ICONERROR);
        return 0;
    }    hwnd=CreateWindow(szAppName,TEXT("ListBox"),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,CW_USEDEFAULT,
        CW_USEDEFAULT,CW_USEDEFAULT,
        NULL,NULL,hInstance,NULL);
//////////////////////////////////////+++++++++++++++++++++++++++
int cxChar,cyChar;    cxChar=LOWORD(GetDialogBaseUnits());
    cyChar=HIWORD(GetDialogBaseUnits());    hwndList=CreateWindow(TEXT("combobox"),NULL,
            WS_CHILD|WS_VISIBLE,
            cxChar,cyChar*3,
            cxChar*32+GetSystemMetrics(SM_CXVSCROLL),
            cyChar*10,
            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);    fillList(hwndList);
////////////////////////////////////++++++++++++++++++++    ShowWindow(hwnd,nShowCmd);
    UpdateWindow(hwnd);    while(GetMessage(&msg,NULL,NULL,NULL)){
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }    return msg.wParam;
}void fillList(HWND hwndList){
    int iLength;
    TCHAR *pVarBlock,*pVarBeg,*pVarEnd,*pVarName;    pVarBlock=GetEnvironmentStrings();
    
    if(pVarBlock==NULL){
        MessageBox(NULL,TEXT("Function Error!"),TEXT("ERROR"),MB_ICONERROR);
        return ;
    }    while(*pVarBlock){
        if(*pVarBlock!='='){
            pVarBeg=pVarBlock;
            while(*pVarBlock++!='=') ;
            pVarEnd=pVarBlock-1;
            iLength=pVarEnd-pVarBeg;
            pVarName=(TCHAR*)calloc(iLength+1,sizeof(TCHAR));
            CopyMemory(pVarName,pVarBeg,iLength*sizeof(TCHAR));
            pVarName[iLength]='\0';
///////////////////////////////////////////////////
            SendMessage(hwndList,CB_ADDSTRING,0,(LPARAM)pVarName);
/////////////////////CB_ADDSTRING->CB_ADDSTRING//////////////////////////
            free(pVarName);
        }
        while(*pVarBlock++!='\0') ;
    }
    FreeEnvironmentStrings(pVarBlock);
}LRESULT CALLBACK WndProc(HWND hwnd,UINT  message,WPARAM wParam,LPARAM lParam){
    int iIndex,iLength;
    TCHAR *pVarName,*pVarValue;    switch(message){
////////////////////////////////////////////------------------------
        case WM_SETFOCUS:
            SetFocus(hwndList);
            return 0;        case WM_COMMAND:
            if(LOWORD(wParam)==ID_LIST&&HIWORD(wParam)==CBN_SELCHANGE){
                iIndex=SendMessage(hwndList,CB_GETCURSEL,0,0);
                iLength=SendMessage(hwndList,CB_GETLBTEXTLEN,iIndex,0)+1;
                pVarName=(TCHAR*)calloc(iLength,sizeof(TCHAR));
                SendMessage(hwndList,CB_GETLBTEXT,iIndex,(LPARAM)pVarName);                iLength=GetEnvironmentVariable(pVarName,NULL,0);
                pVarValue=(TCHAR*)calloc(iLength,sizeof(TCHAR));
                GetEnvironmentVariable(pVarName,pVarValue,iLength);                SetWindowText(hwndText,pVarValue);
                free(pVarName);
                free(pVarValue);
            }
            return 0;        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}//另外所有的LB_...等ListBox属性我也改成了相应的CB_...ComboBox属性。

Answer 2

抱歉，有一处内存泄露
#include <windows.h>#define ID_LIST 1
#define ID_TEXT 2LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);void fillList(HWND);  static HWND hwndList,hwndText;int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd){
  static TCHAR szAppName[]=TEXT("ListBox");
  HWND hwnd;
  MSG msg;
  WNDCLASS wndclass;  wndclass.cbClsExtra=0;
  wndclass.cbWndExtra=0;
  wndclass.lpfnWndProc=WndProc;
  wndclass.hbrBackground=(HBRUSH)(COLOR_WINDOW+1);
  wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
  wndclass.hIcon=LoadIcon(NULL,IDI_ERROR);
  wndclass.hInstance=hInstance;
  wndclass.lpszClassName=szAppName;
  wndclass.lpszMenuName=NULL;
  wndclass.style=CS_HREDRAW|CS_VREDRAW;  if(!RegisterClass(&wndclass)){
  MessageBox(NULL,TEXT("This program requires Windows NT!"),szAppName,MB_ICONERROR);
  return 0;
  }  hwnd=CreateWindow(szAppName,TEXT("ListBox"),
  WS_OVERLAPPEDWINDOW,
  CW_USEDEFAULT,CW_USEDEFAULT,
  CW_USEDEFAULT,CW_USEDEFAULT,
  NULL,NULL,hInstance,NULL);
//////////////////////////////////////+++++++++++++++++++++++++++
int cxChar,cyChar;  cxChar=LOWORD(GetDialogBaseUnits());
  cyChar=HIWORD(GetDialogBaseUnits());  hwndList=CreateWindow(TEXT("combobox"),NULL,
  WS_CHILD|WS_VISIBLE,
  cxChar,cyChar*3,
  cxChar*32+GetSystemMetrics(SM_CXVSCROLL),
  cyChar*10,
  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);  fillList(hwndList);
////////////////////////////////////++++++++++++++++++++  ShowWindow(hwnd,nShowCmd);
  UpdateWindow(hwnd);  while(GetMessage(&msg,NULL,NULL,NULL)){
  TranslateMessage(&msg);
  DispatchMessage(&msg);
  }  return msg.wParam;
}void fillList(HWND hwndList){
  int iLength;
  TCHAR *pVarBlock,*pVarBeg,*pVarEnd,*pVarName;  pVarBlock=GetEnvironmentStrings();
    
  if(pVarBlock==NULL){
  MessageBox(NULL,TEXT("Function Error!"),TEXT("ERROR"),MB_ICONERROR);
  return ;
  }  while(*pVarBlock){
  if(*pVarBlock!='='){
  pVarBeg=pVarBlock;
  while(*pVarBlock++!='=') ;
  pVarEnd=pVarBlock-1;
  iLength=pVarEnd-pVarBeg;
  pVarName=(TCHAR*)calloc(iLength+1,sizeof(TCHAR));
  CopyMemory(pVarName,pVarBeg,iLength*sizeof(TCHAR));
  pVarName[iLength]='\0';
///////////////////////////////////////////////////
  SendMessage(hwndList,CB_ADDSTRING,0,(LPARAM)pVarName);
/////////////////////CB_ADDSTRING->CB_ADDSTRING//////////////////////////
  free(pVarName);
  }
  while(*pVarBlock++!='\0') ;
  }
  //FreeEnvironmentStrings(pVarBlock);//Memory Leak Here.
}LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam){
  int iIndex,iLength;
  TCHAR *pVarName,*pVarValue;  switch(message){
////////////////////////////////////////////------------------------
  case WM_SETFOCUS:
  SetFocus(hwndList);
  return 0;  case WM_COMMAND:
  if(LOWORD(wParam)==ID_LIST&&HIWORD(wParam)==CBN_SELCHANGE){
  iIndex=SendMessage(hwndList,CB_GETCURSEL,0,0);
  iLength=SendMessage(hwndList,CB_GETLBTEXTLEN,iIndex,0)+1;
  pVarName=(TCHAR*)calloc(iLength,sizeof(TCHAR));
  SendMessage(hwndList,CB_GETLBTEXT,iIndex,(LPARAM)pVarName);  iLength=GetEnvironmentVariable(pVarName,NULL,0);
  pVarValue=(TCHAR*)calloc(iLength,sizeof(TCHAR));
  GetEnvironmentVariable(pVarName,pVarValue,iLength);  SetWindowText(hwndText,pVarValue);
  free(pVarName);
  free(pVarValue);
  }
  return 0;  case WM_DESTROY:
  PostQuitMessage(0);
  return 0;
  }
  return DefWindowProc(hwnd,message,wParam,lParam);
}//另外所有的LB_...等ListBox属性我也改成了相应的CB_...ComboBox属性。