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VB.net有什么函数能统计“汉字、全角字符”这些占用两个字节的数量？
VB使用Unicode编码，任何字符（包括半角的字母、数字、符号及全角的汉字、符号等）都是占用两个字节的。
Len()
函数返回字符串的字符个数（要注意，一个汉字也是算作一个字符的）
比如：
Len("百度baidu")的返回值为7
LenB()
函数返回字符串的占用字节数
比如：
LenB("百度baidu")的返回值为14
相关问答
Q1: 怎样用VB脚本枚举注册表属性
Option Explicit
'注册表主键
Public Enum enumRegMainKey
iHKEY_CURRENT_USER = H80000001
iHKEY_LOCAL_MACHINE = H80000002
iHKEY_CLASSES_ROOT = H80000000
iHKEY_CURRENT_CONFIG = H80000005
iHKEY_USERS = H80000003
End Enum
'注册表数据类型
Public Enum enumRegSzType
iREG_SZ = H1
iREG_EXPAND_SZ = H2
iREG_BINARY = H3
iREG_DWORD = H4
iREG_NONE = 0
iREG_DWORD_LITTLE_ENDIAN = 4
iREG_DWORD_BIG_ENDIAN = 5
iREG_LINK = 6
iREG_MULTI_SZ = 7
iREG_RESOURCE_LIST = 8
iREG_FULL_RESOURCE_DESCRIPTOR = 9
iREG_RESOURCE_REQUIREMENTS_LIST = 10
End Enum
'注册表
Private Const ERROR_SUCCESS = 0
Private Const ERROR_BADDB = 1009
Private Const ERROR_BADKEY = 1010
Private Const ERROR_CANTOPEN = 1011
Private Const ERROR_CANTREAD = 1012
Private Const ERROR_CANTWRITE = 1013
Private Const ERROR_OUTOFMEMORY = 14
Private Const ERROR_INVALID_PARAMETER = 87
Private Const ERROR_ACCESS_DENIED = 5
Private Const ERROR_NO_MORE_ITEMS = 259
Private Const ERROR_MORE_DATA = 234
Private Const KEY_QUERY_VALUE = H1
Private Const KEY_SET_VALUE = H2
Private Const KEY_CREATE_SUB_KEY = H4
Private Const KEY_ENUMERATE_SUB_KEYS = H8
Private Const KEY_NOTIFY = H10
Private Const KEY_CREATE_LINK = H20
Private Const SYNCHRONIZE = H100000
Private Const READ_CONTROL = H20000
Private Const WRITE_DAC = H40000
Private Const WRITE_OWNER = H80000
Private Const STANDARD_RIGHTS_REQUIRED = HF0000
Private Const STANDARD_RIGHTS_READ = READ_CONTROL
Private Const STANDARD_RIGHTS_WRITE = READ_CONTROL
Private Const STANDARD_RIGHTS_EXECUTE = READ_CONTROL
Private Const KEY_READ = STANDARD_RIGHTS_READ Or KEY_QUERY_VALUE Or KEY_ENUMERATE_SUB_KEYS Or KEY_NOTIFY
Private Const KEY_WRITE = STANDARD_RIGHTS_WRITE Or KEY_SET_VALUE Or KEY_CREATE_SUB_KEY
Private Const KEY_EXECUTE = KEY_READ
Private Declare Function RegCreateKey Lib "advapi32.dll" Alias "RegCreateKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegCreateKeyEx Lib "advapi32.dll" Alias "RegCreateKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal Reserved As Long, ByVal lpClass As String, ByVal dwOptions As Long, ByVal samDesired As Long, lpSecurityAttributes As SECURITY_ATTRIBUTES, phkResult As Long, lpdwDisposition As Long) As Long
Private Declare Function RegEnumValue Lib "advapi32.dll" Alias "RegEnumValueA" (ByVal hKey As Long, ByVal dwIndex As Long, ByVal lpValueName As String, lpcbValueName As Long, ByVal lpReserved As Long, lpType As Long, lpData As Byte, lpcbData As Long) As Long
Private Declare Function RegEnumKeyEx Lib "advapi32.dll" Alias "RegEnumKeyExA" (ByVal hKey As Long, ByVal dwIndex As Long, ByVal lpName As String, lpcbName As Long, ByVal lpReserved As Long, ByVal lpClass As String, lpcbClass As Long, lpftLastWriteTime As FILETIME) As Long
Private Declare Function RegOpenKeyEx Lib "advapi32.dll" Alias "RegOpenKeyExA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As Long) As Long
Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Private Declare Function RegDeleteValue Lib "advapi32.dll" Alias "RegDeleteValueA" (ByVal hKey As Long, ByVal lpValueName As String) As Long
Private Declare Function RegSetValueEx Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, ByVal lpData As String, ByVal cbData As Long) As Long
Private Declare Function RegSetValueExLong Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpData As Long, ByVal cbData As Long) As Long
Private Declare Function RegSetValueExA Lib "advapi32.dll" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, ByRef lpData As Long, ByVal cbData As Long) As Long
Private Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long ' Note that if you declare the lpData parameter as String, you must pass it By Value.
Private Declare Function RegDeleteKey Lib "advapi32.dll" Alias "RegDeleteKeyA" (ByVal hKey As Long, ByVal lpSubKey As String) As Long
Private Declare Function RegSaveKey Lib "advapi32.dll" Alias "RegSaveKeyA" (ByVal hKey As Long, ByVal lpFile As String, ByVal lpSecurityAttributes As Long) As Long
Private Declare Function RegRestoreKey Lib "advapi32.dll" Alias "RegRestoreKeyA" (ByVal hKey As Long, ByVal lpFile As String, ByVal dwflags As Long) As Long
Private Type FILETIME
dwLowDateTime As Long
dwHighDateTime As Long
End Type
Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Boolean
End Type
Public Function GetValue(ByVal mainKey As enumRegMainKey, _
ByVal subKey As String, _
ByVal keyV As String, _
ByRef sValue As Variant, _
Optional ByRef rlngErrNum As Long, _
Optional ByRef rstrErrDescr As String) As Boolean
Dim hKey As Long, lType As Long, lBuffer As Long, sBuffer As String, lData As Long
On Error GoTo GetValueErr
GetValue = False
If RegOpenKeyEx(mainKey, subKey, 0, KEY_READ, hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
If RegQueryValueEx(hKey, keyV, 0, lType, ByVal 0, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
Select Case lType
Case iREG_SZ
lBuffer = 255
sBuffer = Space(lBuffer)
If RegQueryValueEx(hKey, keyV, 0, lType, ByVal sBuffer, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
sValue = Left(sBuffer, InStr(sBuffer, Chr(0)) - 1)
Case iREG_EXPAND_SZ
sBuffer = Space(lBuffer)
If RegQueryValueEx(hKey, keyV, 0, lType, ByVal sBuffer, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
sValue = Left(sBuffer, InStr(sBuffer, Chr(0)) - 1)
Case iREG_DWORD
If RegQueryValueEx(hKey, keyV, 0, lType, lData, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
sValue = lData
Case iREG_BINARY
If RegQueryValueEx(hKey, keyV, 0, lType, lData, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
sValue = lData
End Select
If RegCloseKey(hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "获取注册表值时出错"
End If
GetValue = True
Err.Clear
GetValueErr:
rlngErrNum = Err.Number
rstrErrDescr = Err.Description
End Function
Public Function SetValue(ByVal mainKey As enumRegMainKey, _
ByVal subKey As String, _
ByVal keyV As String, _
ByVal lType As enumRegSzType, _
ByVal sValue As Variant, _
Optional ByRef rlngErrNum As Long, _
Optional ByRef rstrErrDescr As String) As Boolean
Dim S As Long, lBuffer As Long, hKey As Long
Dim ss As SECURITY_ATTRIBUTES
On Error GoTo SetValueErr
SetValue = False
ss.nLength = Len(ss)
ss.lpSecurityDescriptor = 0
ss.bInheritHandle = True
If RegCreateKeyEx(mainKey, subKey, 0, "", 0, KEY_WRITE, ss, hKey, S) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
Select Case lType
Case iREG_SZ
lBuffer = LenB(sValue)
If RegSetValueEx(hKey, keyV, 0, lType, ByVal sValue, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
Case iREG_EXPAND_SZ
lBuffer = LenB(sValue)
If RegSetValueEx(hKey, keyV, 0, lType, ByVal sValue, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
Case iREG_DWORD
lBuffer = 4
If RegSetValueExA(hKey, keyV, 0, lType, sValue, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
Case iREG_BINARY
lBuffer = 4
If RegSetValueExA(hKey, keyV, 0, lType, sValue, lBuffer) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
Case Else
Err.Raise vbObjectError + 1, , "不支持该参数类型"
End Select
If RegCloseKey(hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "设置注册表时出错"
End If
SetValue = True
Err.Clear
SetValueErr:
rlngErrNum = Err.Number
rstrErrDescr = Err.Description
End Function
Public Function DeleteValue(ByVal mainKey As enumRegMainKey, _
ByVal subKey As String, _
ByVal keyV As String, _
Optional ByRef rlngErrNum As Long, _
Optional ByRef rstrErrDescr As String) As Boolean
Dim hKey As Long
On Error GoTo DeleteValueErr
DeleteValue = False
If RegOpenKeyEx(mainKey, subKey, 0, KEY_WRITE, hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
If RegDeleteValue(hKey, keyV) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
If RegCloseKey(hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
DeleteValue = True
Err.Clear
DeleteValueErr:
rlngErrNum = Err.Number
rstrErrDescr = Err.Description
End Function
Public Function DeleteKey(ByVal mainKey As enumRegMainKey, _
ByVal subKey As String, _
ByVal keyV As String, _
Optional ByRef rlngErrNum As Long, _
Optional ByRef rstrErrDescr As String) As Boolean
Dim hKey As Long
On Error GoTo DeleteKeyErr
DeleteKey = False
If RegOpenKeyEx(mainKey, subKey, 0, KEY_WRITE, hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
If RegDeleteKey(hKey, keyV) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
If RegCloseKey(hKey) ERROR_SUCCESS Then
Err.Raise vbObjectError + 1, , "删除注册表值时出错"
End If
DeleteKey = True
Err.Clear
DeleteKeyErr:
rlngErrNum = Err.Number
rstrErrDescr = Err.Description
End Function
Q2: VB.net为什么取消了“lenb”“midb”这些函数，.net又如何通过变通方法来实现？
include QtCore/QCoreApplication
#include QAxObject
#include Windows.h
int main(int argc, char *argv[])
{
//OleInitialize(0);
//CoInitialize(0);
QCoreApplication a(argc, argv);
QAxObject *asdfg = new QAxObject("Excel.Application");
return a.exec();
}
Q3: VB.net的mid函数如何按照“字节数”来截取，而不用“字符数”，也就是汉字、全角符号要算2个字节
VB内部采用Unicode编码，在这种编码格式下，任何字符（包括半角的字母、数字、符号以及全角的汉字、符号）都是占用两个字节的。因此，Len("1111徐")的返回值是5，表示5个字符，而LenB("1111徐")的返回值是10，表示占用10个字节。
要想按ANSI编码格式来获取字符串的字节数，必须这样：
LenB(StrConv("1111徐", vbFromUnicode))
要注意哦，虽然返回值是6，但这个数与这个字符串在内存中的实际占用字节数是不相符的哦！
