以下内容引用"Perhaps的小窝" 最近用vb写一个小程序,需要调用子程序返回一个数组,然后判断这个数组是否为空来验证子程序是否正常工作,因为对vb语言并不熟悉,开始试了很多种方法也没有成功。后来在网上找到了解决办法,摘录如下:方法一:Error方法就是采用通用的错误捕获功能On Error Goto 行号 '遇到错误,转到行号处处理On Error Resume Next '忽略错误,继续执行On Error Goto 0 '强制取消错误捕获功能方法二:CopyMemory方法VB的数组都是安全数组,通过访问一个结构来确定 数组内容保存位置,上标下标和维数 安全数组结构的地址可以用 Private Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (ByRef Ptr() As Any) As Long 和 Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" _ (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long) 获得 安全数组的头两位就保存着维数信息Option Explicit Private Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (ByRef Ptr() As Any) As Long Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long)Private Sub Form_Load() Dim MyArr() As Long Dim pMyarr As Long Dim nDims As Integer
'从数据指针得到SafeArray结构的指针 CopyMemory pMyarr, ByVal VarPtrArray(MyArr), 4 If pMyarr = 0 Then MsgBox "这个数组是空数组" Else '再从这个指针所指地址的头两个字节取出cDims CopyMemory nDims, ByVal pMyarr, 2 MsgBox "这个数组有" & nDims & "维" End If End Sub
{
//...
}
如果不是那么再判断Length
{
//...
}
if(arr!=null)
{
if(arr.length>0)
{
}
}感觉这样比较OK
最近用vb写一个小程序,需要调用子程序返回一个数组,然后判断这个数组是否为空来验证子程序是否正常工作,因为对vb语言并不熟悉,开始试了很多种方法也没有成功。后来在网上找到了解决办法,摘录如下:方法一:Error方法就是采用通用的错误捕获功能On Error Goto 行号 '遇到错误,转到行号处处理On Error Resume Next '忽略错误,继续执行On Error Goto 0 '强制取消错误捕获功能方法二:CopyMemory方法VB的数组都是安全数组,通过访问一个结构来确定 数组内容保存位置,上标下标和维数
安全数组结构的地址可以用
Private Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (ByRef Ptr() As Any) As Long
和
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" _
(ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long)
获得
安全数组的头两位就保存着维数信息Option Explicit
Private Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (ByRef Ptr() As Any) As Long
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long)Private Sub Form_Load()
Dim MyArr() As Long
Dim pMyarr As Long
Dim nDims As Integer
'从数据指针得到SafeArray结构的指针
CopyMemory pMyarr, ByVal VarPtrArray(MyArr), 4
If pMyarr = 0 Then
MsgBox "这个数组是空数组"
Else
'再从这个指针所指地址的头两个字节取出cDims
CopyMemory nDims, ByVal pMyarr, 2
MsgBox "这个数组有" & nDims & "维"
End If
End Sub