HDC hdc;
    PAINTSTRUCT pt;

    static HWND hwndedit,hwndbutton;
    char str[10]="";
    switch(uMsg)
    {
    case WM_COMMAND:
        if(((HWND)lParam==hwndbutton)&&(HIWORD(wParam)==BN_CLICKED))
        {
        GetWindowText(hwndedit,str,10);
        return 0;
        }
        break;
    case WM_PAINT:
        hdc=BeginPaint(hwnd,&pt);
        TextOut(hdc,200,200,str,strlen(str));
        EndPaint(hwnd,&pt);
        break;
    case WM_CREATE:
        hwndedit=CreateWindow("edit",NULL,WS_CHILD|WS_VISIBLE|WS_BORDER,10,60,100,25,hwnd,NULL,NULL,NULL);
        ShowWindow(hwnd,SW_SHOWNORMAL);

        hwndbutton=CreateWindow("button","计算",WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,100,150,100,25,hwnd,NULL,NULL,NULL);
        ShowWindow(hwnd,SW_SHOWNORMAL);
        break;

我调试过:str没有得到输入框中的的文本,谢谢,那位教一下,怎么改

如果是MFC则要在获得前加上
UpdateData();