自已做的AsniStr类

最近在学Delphi,感叹它的框架，而VB6没有自已框架。

从中获得了一些灵感。自已做了一个clsAnsiStr类。

'---ClsAnsStr---Strart

Private Declare Function lstrlenStr Lib "kernel32" Alias "lstrlenA" (ByVal lpString As String) As Long
Private Declare Function lstrlen Lib "kernel32" Alias "lstrlenA" (ByVal lpString As Long) As Long

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Declare Sub CopyMemorySrcStr Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, ByVal Source As String, ByVal Length As Long)
Private Declare Sub CopyMemoryDstStr Lib "kernel32" Alias "RtlMoveMemory" (ByVal Destination As String, Source As Any, ByVal Length As Long)

Private b() As Byte
Private FLength As Long

Private Sub Class_Initialize()
    ReDim b(0)
    Flenght = 0
End Sub

 

Public Property Get Ptr() As Long
    Ptr = VarPtr(b(0))
End Property

Public Function FromVBStr(s As String)
    FLength = lstrlenStr(s)
    Length = FLength
   
    CopyMemory ByVal Ptr, s, FLength
   
   
End Function

Public Property Get Length() As Long
    Length = FLength
End Property

Public Property Let Length(ByVal vNewValue As Long)
    If vNewValue < 0 Then Exit Property
    ReDim Preserve b(vNewValue)
    CopyMemory b(vNewValue), 0&, 1
    FLength = vNewValue
   
End Property

Public Function ToVBStr() As String
   
    If FLength > 0 Then
        ToVBStr = String(FLength, " ")
        CopyMemoryDstStr ToVBStr, ByVal Ptr, FLength
    End If
   
End Function

'--------clsAnsiStrEnd---

这样，VB在调用api有字符串指针时就方便多了（申明时全可以改成byval lpStr as long 了,免得调用时出错) 。如下。

 

Private Declare Function GetSystemDirectory Lib "kernel32" Alias "GetSystemDirectoryA" (ByVal lpBuffer As Long, ByVal nSize As Long) As Long

Private Sub Command1_Click()
    Dim x As New clsAnsiString
    x.Length = 256
    x.Length = GetSystemDirectory(x.Ptr, 255)
    Debug.Print x.ToVBStr
   
End Sub

Private Sub Form_Load()

End Sub
最后，我由此类想到很多关于指针的应用。