谢谢。很奇怪,内置byte()是就不行了。 Dim arrVar As Variant Dim a() As Byte ReDim a(2) a(0) = 0 a(1) = 10 a(2) = 20 Debug.Print TypeName(arrVar) arrVar = a Debug.Print TypeName(arrVar) Debug.Print TypeName(arrVar(LBound(arrVar))) Debug.Print VarPtr(arrVar(LBound(arrVar))) '数组的首元素的地址 Debug.Print VarPtr(arrVar(LBound(arrVar) + 1))
不是Byte的问题,从你这个测试来看,对Variant变量arrVar直接赋值数组后,VarPtr(arrVar())这样的操作并非取得实际的元素地址,那就不用钻牛角尖了。需要直接访问地址时,先再赋值回给一个标准的动态数组再处理吧:arrVar = a Dim b() As Byte b = arrVar
Option ExplicitType userVARIANT vt As Integer wReserved1 As Integer wReserved2 As Integer wReserved3 As Integer dwReserved1 As Long dwReserved2 As Long End TypeConst VT_BYREF = &H4000Sub Main() Dim arrVar As Variant Dim a() As Byte ReDim a(2) Debug.Print Hex(VarPtr(a(0))) arrVar = a Debug.Print Hex(GetpvData(VarPtr(arrVar))) TestByRef a TestByVal a End SubFunction GetpvData(ByVal pV As Long) As Long Dim v As userVARIANT Dim sa As SafeArray Dim pSA As Long CopyMemory v, ByVal pV, Len(v) If CBool(v.vt And VT_BYREF) Then CopyMemory pSA, ByVal v.dwReserved1, 4 Else pSA = v.dwReserved1 End If CopyMemory sa, ByVal pSA, Len(sa) GetpvData = sa.pvData End FunctionSub TestByRef(ByRef arrVar As Variant) Debug.Print Hex(GetpvData(VarPtr(arrVar))) End SubSub TestByVal(ByVal arrVar As Variant) Debug.Print Hex(GetpvData(VarPtr(arrVar))) End Sub 没加容错处理。
可以看出 TestByRef 是对原数组的引用,直接赋值和 TestByVal 都复制了数组。
赵老虎的函数:Function GetpvData(ByVal pV As Long) As Long Dim v As userVARIANT Dim sa As SafeArray Dim pSA As Long
CopyMemory v, ByVal pV, Len(v) If CBool(v.vt And VT_BYREF) Then CopyMemory pSA, ByVal v.dwReserved1, 4 Else pSA = v.dwReserved1 End If
CopyMemory sa, ByVal pSA, Len(sa) GetpvData = sa.pvData End Function 嗯,这就是解析VARIANT及SAFEARRAY的具体实现了。
' 过程名 : TestVariant
' 时间 : 2013/3/30
' 作者 : 杨过.网狐.cn(csdn bcrun)
' 功能 :
' 说明 :
' 备注 : 星辰设计室VB一群:283362041,星辰学园BASIC辅导群:289219875
'---------------------------------------------------------------------------------------
Public Sub TestVariant()
Dim arrVar As Variant
Debug.Print TypeName(arrVar)
arrVar = Array("a1", "b2", "c3")
Debug.Print TypeName(arrVar)
Debug.Print TypeName(arrVar(LBound(arrVar)))
Debug.Print VarPtr(arrVar(LBound(arrVar))) '数组的首元素的地址
End Sub
Dim a() As Byte
ReDim a(2)
a(0) = 0
a(1) = 10
a(2) = 20
Debug.Print TypeName(arrVar)
arrVar = a
Debug.Print TypeName(arrVar)
Debug.Print TypeName(arrVar(LBound(arrVar)))
Debug.Print VarPtr(arrVar(LBound(arrVar))) '数组的首元素的地址
Debug.Print VarPtr(arrVar(LBound(arrVar) + 1))
Dim b() As Byte
b = arrVar
你说的这种情况,我估计很可能编译环境是把arrVar()处理成类似函数返回值的形式了,所以不管括号你的数字是几,对应的varptr都一样。想想VB里的mid()即可放在=左边又可放在右边,唉,怎么处理最终还是编译器说了算。其实啊,各种语言里都能多少找到一些疑似BUG的语法或编译器处理的方式,如果看重代码的易读和易移植性的话,应尽量避免使用这类写法,或者实在需要这样写时,认真写好代码注释。BTW,前几天在这个帖子的8楼回复了一段有点关系的代码,这里提一下
ByVal 与 ByRef求解
参考下面:http://blog.csdn.net/laviewpbt/article/details/4216686
typedef struct FARSTRUCT tagVARIANT VARIANTARG;typedef struct tagVARIANT {
VARTYPE vt;
unsigned short wReserved1;
unsigned short wReserved2;
unsigned short wReserved3;
union {
unsigned char bVal; // VT_UI1.
short iVal; // VT_I2 .
long lVal; // VT_I4 .
float fltVal; // VT_R4 .
double dblVal; // VT_R8 .
VARIANT_BOOL boolVal; // VT_BOOL.
SCODE scode; // VT_ERROR.
CY cyVal; // VT_CY .
DATE date; // VT_DATE.
BSTR bstrVal; // VT_BSTR.
IUnknown FAR* punkVal; // VT_UNKNOWN.
IDispatch FAR* pdispVal; // VT_DISPATCH.
SAFEARRAY FAR* parray; // VT_ARRAY|*.
unsigned char FAR* pbVal; // VT_BYREF|VT_UI1.
short FAR* piVal; // VT_BYREF|VT_I2.
long FAR* plVal; // VT_BYREF|VT_I4.
float FAR* pfltVal; // VT_BYREF|VT_R4.
double FAR* pdblVal; // VT_BYREF|VT_R8.
VARIANT_BOOL FAR* pboolVal; // VT_BYREF|VT_BOOL.
SCODE FAR* pscode; // VT_BYREF|VT_ERROR.
CY FAR* pcyVal; // VT_BYREF|VT_CY.
DATE FAR* pdate; // VT_BYREF|VT_DATE.
BSTR FAR* pbstrVal; // VT_BYREF|VT_BSTR.
IUnknown FAR* FAR* ppunkVal; // VT_BYREF|VT_UNKNOWN.
IDispatch FAR* FAR* ppdispVal; // VT_BYREF|VT_DISPATCH.
SAFEARRAY FAR* FAR* pparray; // VT_ARRAY|*.
VARIANT FAR* pvarVal; // VT_BYREF|VT_VARIANT.
void FAR* byref; // Generic ByRef.
};
};先得到地址,再去解析......
http://download.csdn.net/detail/veron_04/1371398
vt As Integer
wReserved1 As Integer
wReserved2 As Integer
wReserved3 As Integer
dwReserved1 As Long
dwReserved2 As Long
End TypeConst VT_BYREF = &H4000Sub Main()
Dim arrVar As Variant
Dim a() As Byte
ReDim a(2)
Debug.Print Hex(VarPtr(a(0))) arrVar = a
Debug.Print Hex(GetpvData(VarPtr(arrVar))) TestByRef a
TestByVal a
End SubFunction GetpvData(ByVal pV As Long) As Long
Dim v As userVARIANT
Dim sa As SafeArray
Dim pSA As Long CopyMemory v, ByVal pV, Len(v)
If CBool(v.vt And VT_BYREF) Then
CopyMemory pSA, ByVal v.dwReserved1, 4
Else
pSA = v.dwReserved1
End If CopyMemory sa, ByVal pSA, Len(sa)
GetpvData = sa.pvData
End FunctionSub TestByRef(ByRef arrVar As Variant)
Debug.Print Hex(GetpvData(VarPtr(arrVar)))
End SubSub TestByVal(ByVal arrVar As Variant)
Debug.Print Hex(GetpvData(VarPtr(arrVar)))
End Sub
没加容错处理。
Dim v As userVARIANT
Dim sa As SafeArray
Dim pSA As Long
CopyMemory v, ByVal pV, Len(v)
If CBool(v.vt And VT_BYREF) Then
CopyMemory pSA, ByVal v.dwReserved1, 4
Else
pSA = v.dwReserved1
End If
CopyMemory sa, ByVal pSA, Len(sa)
GetpvData = sa.pvData
End Function
嗯,这就是解析VARIANT及SAFEARRAY的具体实现了。
http://www.cnblogs.com/pctgl/articles/1540556.html
获取安全数组信息
Des:
获取安全数组的信息,包括安全数组结构内的所有数据
本来用结构做的话,更方便,但会增加代码量,而且用起来也会麻烦些,所以就用了N多变量了
有兴趣的朋友可以再改改Private Function GetSafeArrayInfo(AnyArray As Variant, Optional sDimension As Integer, Optional LowerBound As Long, Optional UpperBound As Long, Optional Elements As Long, Optional Flags As Integer, Optional cbElements As Long, Optional cLocks As Long, Optional AddressOfData As Long) As Long
'**************************************************************
'*
'* 数组头地址 = GetSafeArrayInfo(数组 ,[维数],[下标],[上标],[元素个数],[属性],[元素长度],[锁定计数],[首元素地址])
'*
'* result: 成功返回数组头地址; 返回 0 代表这是一个未被初始化过的数组
'*
'* note: 除第1个参数外,均为输出型参数,要获取数组的什么信息,传入相应的变量,执行后,变量的值即为相应的数组数据
'*
'* 要获取多维数组的非第1维的上/下标,应按照下面的方法调用
'*
'* GetSafeArrayInfo (数组, 指定一个维数,[下标],[上标]
'*
'************************************************************** Dim ArrayHeaderAddress As Long
Dim DimensionCount As Integer '维数计次 CopyMemory ArrayHeaderAddress, ByVal VarPtr(AnyArray) + 8, 4
CopyMemory ArrayHeaderAddress, ByVal ArrayHeaderAddress, 4 '获取数组头地址
If ArrayHeaderAddress < 1 Then Exit Function CopyMemory DimensionCount, ByVal ArrayHeaderAddress, 2 '获取数组维数 If sDimension > DimensionCount Then Exit Function '若指定的维数大于实际维数则退出 CopyMemory LowerBound, ByVal (ArrayHeaderAddress + 16 + (DimensionCount - sDimension) * 8) + 4, 4 '获取下标
CopyMemory Elements , ByVal (ArrayHeaderAddress + 16 + (DimensionCount - sDimension) * 8), 4 '获取指定维数下的元素个数
UpperBound = Elements + LowerBound - 1 '获取指定维数下的上标
CopyMemory Flags, ByVal ArrayHeaderAddress + 2, 2 '获取数组属性
CopyMemory cbElements, ByVal ArrayHeaderAddress + 4, 2 '获取数组单个元素长度
CopyMemory cLocks, ByVal ArrayHeaderAddress + 8, 2 '获取数组锁定计数
CopyMemory AddressOfData, ByVal ArrayHeaderAddress + 12, 4 '获取数组首元素地址
GetSafeArrayInfo = ArrayHeaderAddress
End Function