Private Declare Function SHEmptyRecycleBin Lib "shell32.dll" Alias _
"SHEmptyRecycleBinA" (ByVal hwnd As Long, ByVal pszRootPath As String, _
ByVal dwFlags As Long) As Long
Private Declare Function SHUpdateRecycleBinIcon Lib "shell32.dll" () As Long
Private Const SHERB_NOCONFIRMATION = &H1
Private Const SHERB_NOPROGRESSUI = &H2
Private Const SHERB_NOSOUND = &H4
Private Sub Command1_Click()
Dim retval As Long ' return value
retval = SHEmptyRecycleBin(RecycleBin.hwnd, "", SHERB_NOPROGRESSUI) ' 清空回收站, 确认
' 若有错误出现，则返回回收站图示
If retval <> 0 Then ' error
retval = SHUpdateRecycleBinIcon()
End If
End Sub
Private Sub Command2_Click()
Dim retval As Long ' return value
' 清空回收站, 不确认
retval = SHEmptyRecycleBin(RecycleBin.hwnd, "", SHERB_NOCONFIRMATION)
' 若有错误出现，则返回回收站图示
If retval <> 0 Then ' error
retval = SHUpdateRecycleBinIcon()
End If
Command1_Click
End Sub
28.获得系统文件夹的路径
Private Declare Function GetSystemDirectory Lib "kernel32" Alias _
"GetSystemDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long
Private Sub Command1_Click()
Dim syspath As String
Dim len5 As Long
syspath = String(255, 0)
len5 = GetSystemDirectory(syspath, 256)
syspath = Left(syspath, InStr(1, syspath, Chr(0)) - 1)
Debug.Print "System Path : "; syspath
End Sub
29.动态增加控件并响应事件
Option Explicit
'通过使用WithEvents关键字声明一个对象变量为新的命令按钮
Private WithEvents NewButton As CommandButton
'增加控件
Private Sub Command1_Click()
If NewButton Is Nothing Then
'增加新的按钮cmdNew
Set NewButton = Controls.Add("VB.CommandButton", "cmdNew", Me)
'确定新增按钮cmdNew的位置
NewButton.Move Command1.Left Command1.Width 240, Command1.Top
NewButton.Caption = "新增的按钮"
NewButton.Visible = True
End If
End Sub
'删除控件(注：只能删除动态增加的控件)
Private Sub Command2_Click()
If NewButton Is Nothing Then
Else
Controls.Remove NewButton
Set NewButton = Nothing
End If
End Sub
'新增控件的单击事件
Private Sub NewButton_Click()
MsgBox "您选中的是动态增加的按钮！"
End Sub
30.得到磁盘序列号
Function GetSerialNumber(strDrive As String) As Long
Dim SerialNum As Long
Dim Res As Long
Dim Temp1 As String
Dim Temp2 As String
Temp1 = String$(255, Chr$(0))
Temp2 = String$(255, Chr$(0))
Res = GetVolumeInformation(strDrive, Temp1, Len(Temp1), SerialNum, 0, 0, Temp2, _
Len(Temp2))
GetSerialNumber = SerialNum
End Function
调用形式 Label1.Caption = GetSerialNumber("c:\")
31.打开屏幕保护
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd _
As Long, ByVal wMsg As Long, ByVal wParam
As Long, lParam As Any) As Long
'我们将要调用的那个消息，在MSDN中搜索WM_SYSCOMMAND就可以找到具体说明
Const WM_SYSCOMMAND = &H112
'这个参数指明了我们让系统启动屏幕保护
Const SC_SCREENSAVE = &HF140&
Private Sub Command1_Click()
SendMessage Me.hwnd, WM_SYSCOMMAND, SC_SCREENSAVE, 0
End Sub
32.获得本机IP地址
方法一：利用Winsock控件
winsockip.localip
方法二：
Private Const MAX_IP = 255
Private Type IPINFO
dwAddr As Long
dwIndex As Long
dwMask As Long
dwBCastAddr As Long
dwReasmSize As Long
unused1 As Integer
unused2 As Integer
End Type
Private Type MIB_IPADDRTABLE
dEntrys As Long
mIPInfo(MAX_IP) As IPINFO
End Type
Private Type IP_Array
mBuffer As MIB_IPADDRTABLE
BufferLen As Long
End Type
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination _
As Any, Source As Any, ByVal Length As
Long)
Private Declare Function GetIpAddrTable Lib "IPHlpApi" (pIPAdrTable As Byte, _
pdwSize As Long, ByVal Sort As Long) As Long
Dim strIP As String
Private Function ConvertAddressToString(longAddr As Long) As String
Dim myByte(3) As Byte
Dim Cnt As Long
CopyMemory myByte(0), longAddr, 4
For Cnt = 0 To 3
ConvertAddressToString = ConvertAddressToString CStr(myByte(Cnt)) "."
Next Cnt
ConvertAddressToString = Left$(ConvertAddressToString, Len(ConvertAddressToString) - 1)
End Function
Public Sub Start()
Dim Ret As Long, Tel As Long
Dim bBytes() As Byte
Dim Listing As MIB_IPADDRTABLE
On Error GoTo END1
GetIpAddrTable ByVal 0&, Ret, True
If Ret <= 0 Then Exit Sub
ReDim bBytes(0 To Ret - 1) As Byte
GetIpAddrTable bBytes(0), Ret, False
CopyMemory Listing.dEntrys, bBytes(0), 4
strIP = "你机子上有 " & Listing.dEntrys & " 个 IP 地址。" & vbCrLf
strIP = strIP & "------------------------------------------------" & vbCrLf & vbCrLf
For Tel = 0 To Listing.dEntrys - 1
CopyMemory Listing.mIPInfo(Tel), bBytes(4 (Tel * Len(Listing.mIPInfo(0)))), Len _(Listing.mIPInfo(Tel))
strIP = strIP & "IP 地址 : " & ConvertAddressToString(Listing.mIPInfo(Tel).dwAddr) & vbCrLf
Next
Exit Sub
END1:
MsgBox "ERROR"
End Sub
Private Sub Form_Load()
Start
MsgBox strIP
End Sub
33. 用键盘方向键控制COMBOX
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long
Const CB_SHOWDROPDOWN = &H14F
Dim bDrop As Boolean
Private isDo As Boolean
Private Sub Combo1_Click()
If Not isDo Then
isDo = True '<----------回置状态
Exit Sub
Else: MsgBox "safd"
End If
End Sub
Private Sub Combo1_DropDown()
bDrop = True
End Sub
Private Sub Combo1_KeyDown(KeyCode As Integer, Shift As Integer)
If KeyCode = 40 Then
isDo = False
SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, 1, 0
ElseIf KeyCode = 38 Then
isDo = False
If Combo1.ListIndex = 0 Then
If bDrop Then
bDrop = False
SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, 0, 0
End If
End If
End If
End Sub
Private Sub Combo1_KeyUp(KeyCode As Integer, Shift As Integer)
If Combo1.Text = Combo1.List(0) Then
isDo = True
End If
End Sub
Private Sub Form_Load()
isDo = True
Combo1.AddItem "abcd"
Combo1.AddItem "abcd1"
Combo1.AddItem "abcd2"
Combo1.AddItem "abcd3"
End Sub
35.VB下的CRC校验程序
一 计算法
计算法就是依据CRC校验码的产生原理来设计程序。其优点是模块代码少，修改灵活，可移植性好。其缺点为计算量大。为了便于理解，这里假
定了三位数据，而多项式码为A001(hex)。
在窗体上放置一命令按钮Command1，并添加如下代码：
Private Sub Command1_Click()
Dim CRC() As Byte
Dim d() As Byte '待传输数据
ReDim d(2) As Byte
d(0) = 123
d(1) = 112
d(2) = 135
CRC = CRC16(d) '调用CRC16计算函数
'CRC(0)为高位
'CRC(1)为低位
End Sub
注意：在数据传输时CRC的低位可能在前，而高位在后。
Function CRC16(data() As Byte) As String
Dim CRC16Lo As Byte, CRC16Hi As Byte 'CRC寄存器
Dim CL As Byte, CH As Byte '多项式码&HA001
Dim SaveHi As Byte, SaveLo As Byte
Dim i As Integer
Dim Flag As Integer
CRC16Lo = &HFF
CRC16Hi = &HFF
CL = &H1
CH = &HA0
For i = 0 To UBound(data)
CRC16Lo = CRC16Lo Xor data(i) '每一个数据与CRC寄存器进行异或
For Flag = 0 To 7
SaveHi = CRC16Hi
SaveLo = CRC16Lo
CRC16Hi = CRC16Hi \ 2 '高位右移一位
CRC16Lo = CRC16Lo \ 2 '低位右移一位
If ((SaveHi And &H1) = &H1) Then '如果高位字节最后一位为1
CRC16Lo = CRC16Lo Or &H80 '则低位字节右移后前面补1
End If '否则自动补0
If ((SaveLo And &H1) = &H1) Then '如果LSB为1，则与多项式码进行异或
CRC16Hi = CRC16Hi Xor CH
CRC16Lo = CRC16Lo Xor CL
End If
Next Flag
Next i
Dim ReturnData(1) As Byte
ReturnData(0) = CRC16Hi 'CRC高位
ReturnData(1) = CRC16Lo 'CRC低位
CRC16 = ReturnData
End Function
2．查表法
查表法的优缺点与计算法的正好相反。为了便于比较，这里所有的假定与计算法的完全相同，都而在窗体上放置一个Command1的按钮，其
代码部分与上面的也完全一致。下面只介绍CRC函数的编写源代码。
Private Function CRC16(data() As Byte) As String
Dim CRC16Hi As Byte
Dim CRC16Lo As Byte
CRC16Hi = &HFF
CRC16Lo = &HFF
Dim i As Integer
Dim iIndex As Long
For i = 0 To UBound(data)
iIndex = CRC16Lo Xor data(i)
CRC16Lo = CRC16Hi Xor GetCRCLo(iIndex) '低位处理
CRC16Hi = GetCRCHi(iIndex) '高位处理
Next i
Dim ReturnData(1) As Byte
ReturnData(0) = CRC16Hi 'CRC高位
ReturnData(1) = CRC16Lo 'CRC低位
CRC16 = ReturnData
End Function
'CRC低位字节值表
Function GetCRCLo(Ind As Long) As Byte
GetCRCLo = Choose(Ind 1, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40,
&H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1,
&H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80,
&H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0,
&HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0,
&H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81,
&H40, &H1, &HC0, &H80, &H41, &H1, &HC0, _
&H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80,
&H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0,
&HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1,
&H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81,
&H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1,
&HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40)
End Function
'CRC高位字节值表
Function GetCRCHi(Ind As Long) As Byte
GetCRCHi = Choose(Ind 1, &H0, &HC0, &HC1, &H1, &HC3, &H3, &H2, &HC2, &HC6, &H6, &H7, &HC7, &H5, &HC5, &HC4, &H4,
&HCC, &HC, &HD, &HCD, &HF, &HCF, &HCE, &HE, &HA, &HCA, &HCB, &HB, &HC9, &H9, &H8, &HC8, &HD8, &H18, &H19, &HD9, &H1B, &HDB,
&HDA, &H1A, &H1E, &HDE, &HDF, &H1F, &HDD, &H1D, &H1C, &HDC, &H14, &HD4, &HD5, &H15, &HD7, &H17, &H16, &HD6, &HD2, &H12, &H13,
&HD3, &H11, &HD1, &HD0, &H10, &HF0, &H30, &H31, &HF1, &H33, &HF3, &HF2, &H32, &H36, &HF6, &HF7, &H37, &HF5, &H35, &H34, &HF4,
&H3C, &HFC, &HFD, &H3D, &HFF, &H3F, &H3E, &HFE, &HFA, &H3A, &H3B, &HFB, &H39, &HF9, &HF8, &H38, &H28, &HE8, &HE9, &H29, &HEB,
&H2B, &H2A, &HEA, &HEE, &H2E, &H2F, &HEF, &H2D, &HED, &HEC, &H2C, &HE4, &H24, &H25, &HE5, &H27, &HE7, &HE6, &H26, &H22, &HE2,
&HE3, &H23, &HE1, &H21, &H20, &HE0, &HA0, &H60, _
&H61, &HA1, &H63, &HA3, &HA2, &H62, &H66, &HA6, &HA7, &H67, &HA5, &H65, &H64, &HA4, &H6C, &HAC, &HAD, &H6D, &HAF, &H6F, &H6E,
&HAE, &HAA, &H6A, &H6B, &HAB, &H69, &HA9, &HA8, &H68, &H78, &HB8, &HB9, &H79, &HBB, &H7B, &H7A, &HBA, &HBE, &H7E, &H7F, &HBF,
&H7D, &HBD, &HBC, &H7C, &HB4, &H74, &H75, &HB5, &H77, &HB7, &HB6, &H76, &H72, &HB2, &HB3, &H73, &HB1, &H71, &H70, &HB0, &H50,
&H90, &H91, &H51, &H93, &H53, &H52, &H92, &H96, &H56, &H57, &H97, &H55, &H95, &H94, &H54, &H9C, &H5C, &H5D, &H9D, &H5F, &H9F,
&H9E, &H5E, &H5A, &H9A, &H9B, &H5B, &H99, &H59, &H58, &H98, &H88, &H48, &H49, &H89, &H4B, &H8B, &H8A, &H4A, &H4E, &H8E, &H8F,
&H4F, &H8D, &H4D, &H4C, &H8C, &H44, &H84, &H85, &H45, &H87, &H47, &H46, &H86, &H82, &H42, &H43, &H83, &H41, &H81, &H80, &H40)
End Function
36.如何打开光驱
Public Declare Function CDdoor Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString
As String, ByVal uReturnLength As Long, ByVal hwndCallback As Long) As Long
Call CDdoor("set CDAudio door open", 0, 0, 0) '打开光驱
Call CDdoor("set CDAudio door closed", 0, 0, 0) '关闭光驱
