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- Option Explicit
- Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
- Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (Var() As Any) As Long 'Command1 click事件
- Sub testarr()
- Dim S(1, 3) As Long '数组定义
- Dim VarPtrArrayAddress As Long '对数组用函数VarPtrArray得到的地址
- Dim SafeArrayPoint As Long 'SafeArray结构的指针的值
- Dim FirstElementOfArray As Long '数组第一个元素的值
- Dim LastElementOfArray As Long '数组最后一个元素的值
- Dim ElementNumOfArray As Long '数组的元素个数
- 'SafeArrays结构各量的定义
- Dim cDims As Integer '
- Dim fFeatures As Integer
- Dim cbElements As Long
- Dim cLocks As Long
- Dim pvData As Long
- Dim rgsabound0_cElements As Long
- Dim rgsabound0_lLbound As Long
- Dim rgsabound1_cElements As Long
- Dim rgsabound1_lLbound As Long
- S(0, 0) = 100: S(1, 0) = 101
- S(0, 1) = 200: S(1, 1) = 201
- S(0, 2) = 300: S(1, 2) = 301
- S(0, 3) = 400: S(1, 3) = 401
- VarPtrArrayAddress = VarPtrArray(S)
- '===========================================================
- CopyMemory SafeArrayPoint, ByVal VarPtrArrayAddress, 4
- '该语句执行后，SafeArrayPoint中的值就是SafeArrays结构的首地址
- '当S为一空数组时.即该数组没有分配内存
- '例如定义的动态数组，没有redim过，只是定义了，但并没有分配内存,这时候SafeArrayPoint的值为0
- '===========================================================
- If SafeArrayPoint = 0 Then Exit Sub
- '获取SafeArrays结构中各内存块的值
- CopyMemory cDims, ByVal SafeArrayPoint + 0, 2
- CopyMemory fFeatures, ByVal SafeArrayPoint + 2, 2
- CopyMemory cbElements, ByVal SafeArrayPoint + 4, 4
- CopyMemory cLocks, ByVal SafeArrayPoint + 8, 4
- CopyMemory pvData, ByVal SafeArrayPoint + 12, 4
- CopyMemory rgsabound0_cElements, ByVal SafeArrayPoint + 16, 4
- CopyMemory rgsabound0_lLbound, ByVal SafeArrayPoint + 20, 4
- CopyMemory rgsabound1_cElements, ByVal SafeArrayPoint + 24, 4
- CopyMemory rgsabound1_lLbound, ByVal SafeArrayPoint + 28, 4
- ElementNumOfArray = rgsabound0_cElements * rgsabound1_cElements '计算数组元素个数
- '通过pvData指针来获取数组第一个元素和最后一个元素的值
- CopyMemory FirstElementOfArray, ByVal pvData + 0, 4 '如果将+0改为+4，就是第2个元素的值，依次类推
- CopyMemory LastElementOfArray, ByVal pvData + (ElementNumOfArray - 1) * 4, 4
- '================显示================
- Debug.Print cDims '数组维数
- Debug.Print pvData '数组第一个元素的指针（地址）
- Debug.Print FirstElementOfArray '数组中第一个元素的值
- Debug.Print LastElementOfArray '数组中最后一个元素的值
- Debug.Print VarPtrArrayAddress '对数组用函数VarPtrArray得到的地址---'结构指针的指针
- Debug.Print SafeArrayPoint 'SafeArray结构的指针的值
- ' Debug.Print fFeatures '
- Debug.Print cbElements '数组元素大小（字节数）
- ' Debug.Print cLocks '
- Debug.Print rgsabound0_cElements '
- Debug.Print rgsabound0_lLbound '
- ' Debug.Print rgsabound1_cElements '
- ' Debug.Print rgsabound1_lLbound '
- '
- End Sub
VB中定义的数组在内存中存储时是以SafeArrays结构方式存储的(字符串数组除外),其定义为:
typedef struct tagSAFEARRAY
{
unsigned short cDims;
unsigned short fFeatures;
unsigned long cbElements;
unsigned long cLocks;
void * pvData;
SAFEARRAYBOUND rgsabound[ ];
} SAFEARRAY;
这个结构的成员（cDims，cLocks等）是通过API函数来设置和管理的。真正的数据存放在pvData成员中，而SAFEARRAYBOUND结构定义该数组结构的细节。以下就是该结构成员的简要描述：
成员 描述 变量大小
cDims 数组的维数----------------------------------------------------------------2个字节
fFeatures 用来描述数组如何分配和如何被释放的标志 -----------------------2个字节
cbElements 数组元素的大小----------------------------------------------------------4个字节
cLocks 数组缩定次数-------------------------------------------------------------4个字节
pvData 指向数组第一个元素的指针(其值就是数组第一个元素的地址)---4个字节
rgsabound[0]- 数组最后一维的大小及起始标(注意:大小非最后一维的下标)-----8个字节
rgsabound[1]-- 数组倒数第二维的大小及起始标---------------------------------------8个字节.....
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rgsabound[cDims-1]-- 数组第一维的大小及起始标 |
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沪公网安备 31011702000001号 沪ICP备11019229号-2
发表于 2009-11-25 16:11
