/*-----------------------------------------------------------------

         ENVIRON.C -- Environment List Box

         (c) Charles Petzold,1998

         Copy by XXXX,2015/1/26

 ------------------------------------------------------------------*/

 #include <windows.h>

 #define ID_LIST 1

 #define ID_TEXT 2

 LRESULT CALLBACK WndProc(HWND 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_VREDRAW | CS_HREDRAW;

     wndclass.lpfnWndProc = WndProc;

     wndclass.cbClsExtra = ;

     wndclass.cbWndExtra = ;

     wndclass.hInstance = hInstance;

     wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);

     wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);

     wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);

     wndclass.lpszMenuName = NULL;

     wndclass.lpszClassName = szAppName;

     if (!RegisterClass(&wndclass))

     {

         MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);

         return ;

     }

     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, , ))

     {

         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 begining with '='

         {

             pVarBeg = pVarBlock;    //Beging of variable name

             while (*(pVarBlock++) != '=');    //Scan until '='

             pVarEnd = pVarBlock - ;    //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 + , sizeof(TCHAR));

             CopyMemory(pVarName, pVarBeg, iLength * sizeof(TCHAR));

             pVarName[iLength] = '\0';

             //Put the variable name int the list box and free memory

             SendMessage(hwndList, LB_ADDSTRING, , (LPARAM)pVarName);

             free(pVarName);

         }

         while (*pVarBlock++ != '\0');    //Scna until terminating zero

     }

     FreeEnvironmentStrings(pVarBlock);

     int code;

     code = GetLastError();

 }

 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 * , cxChar *  + GetSystemMetrics(SM_CXVSCROLL), cyChar * , 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 ;

     case WM_SETFOCUS:

         SetFocus(hwndList);

         return ;

     case WM_COMMAND:

         if (LOWORD(wParam) == ID_LIST&&HIWORD(wParam) == LBN_SELCHANGE)

         {

             //Get current selectiong

             iIndex = SendMessage(hwndList, LB_GETCURSEL, , );

             iLength = SendMessage(hwndList, LB_GETTEXTLEN, iIndex, ) + ;

             pVarName = calloc(iLength, sizeof(TCHAR));

             SendMessage(hwndList, LB_GETTEXT, iIndex, (LPARAM)pVarName);

             //Get environment string

             iLength = GetEnvironmentVariable(pVarName, NULL, );

             pVarValue = calloc(iLength, sizeof(TCHAR));

             GetEnvironmentVariable(pVarName, pVarValue, iLength);

             //Show it in window

             SetWindowText(hwndText, pVarValue);

             free(pVarName);

             free(pVarValue);

         }

         return ;

     case WM_DESTROY:

         PostQuitMessage();

         return ;

     }

     return DefWindowProc(hwnd, message, wParam, lParam);

 }