要怎么addstring windows api

C/C++ code

/*.rc 文件*/TEMP DIALOGEX 0, 0, 316, 185STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENUCAPTION "Dialog"CLASS "temp"FONT 8, "MS Shell Dlg", 400, 0, 0x1BEGIN    DEFPUSHBUTTON   "确定",IDOK,205,164,50,14    PUSHBUTTON      "取消",IDCANCEL,259,164,50,14    COMBOBOX        IDC_COMBO1,166,25,111,82,CBS_DROPDOWN | CBS_SORT | CBS_HASSTRINGS | WS_VSCROLL | WS_TABSTOP    LISTBOX         IDC_LIST1,37,70,108,75,LBS_SORT | LBS_NOINTEGRALHEIGHT | WS_VSCROLL | WS_TABSTOP    COMBOBOX        IDC_COMBO2,197,70,86,63,CBS_DROPDOWN | CBS_SORT | WS_VSCROLL | WS_TABSTOP    LISTBOX         IDC_LIST2,78,25,45,24,LBS_SORT | LBS_NOINTEGRALHEIGHT | WS_VSCROLL | WS_TABSTOPEND/*.c文件*/#include <Windows.h>#include "resource.h"LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam);TCHAR szString[]=TEXT("30");int WINAPI WinMain( HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd ){    static TCHAR szAppName[]=TEXT("temp");    HWND hwnd;    MSG msg;    WNDCLASS wndclass;    wndclass.cbClsExtra=0;    wndclass.cbWndExtra=DLGWINDOWEXTRA;    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);    wndclass.hInstance=hInstance;    wndclass.lpfnWndProc=WndProc;    wndclass.lpszClassName=szAppName;    wndclass.lpszMenuName=NULL;    wndclass.style=CS_HREDRAW | CS_VREDRAW;    if(!RegisterClass(&wndclass))    {        MessageBox(NULL,TEXT("注册失败"),szAppName,MB_ICONERROR);        return 0;    }    hwnd = CreateDialog (hInstance, szAppName,0,NULL);    ShowWindow(hwnd,nShowCmd);    UpdateWindow(hwnd);    while(GetMessage(&msg,NULL,0,0))    {        TranslateMessage(&msg);        DispatchMessage(&msg);    }    return msg.wParam;}LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam){    switch(message)    {    case WM_CREATE:        SendMessage(GetDlgItem(hwnd,IDC_COMBO1),CB_ADDSTRING,0,(LPARAM)szString);        SendMessage(GetDlgItem(hwnd,IDC_COMBO1),CB_ADDSTRING,0,(LPARAM)szString);        return 0;    case WM_DESTROY:        PostQuitMessage(0);        return 0;    }    return DefWindowProc(hwnd,message,wParam,lParam);}

这个为什么combobox1里没加东西了，SendMessage(GetDlgItem(hwnd,IDC_COMBO1),CB_ADDSTRING,0,(LPARAM)szString);后还要进行什么操作吗？

[解决办法]
hwnd = CreateDialog (hInstance, szAppName,0,NULL);
要在case WM_CREATE:
中。
WinMain中要Create主窗口。