How to emulate .net Int64 in VB6? - casting

Question

How can store an Int64 number in VB6, to work with Win32 functions?
Is there a way to define a type like Int64 in .net? And simply evaluate the number.

Answer 1

I think many of VB6 programmers need something like this,
Because some of the Win32 API's use _int64 as their parameters.
I wrote a function to cast a currency into an API compatible structure.
Put these codes in a module file.
Private Declare Sub CopyMemory lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Const SIZEOF_INT64 As Long = 8
Public Type Int64 'LowPart must be the first one in LittleEndian systems
'required part
LowPart As Long
HighPart As Long
'optional part
SignBit As Byte 'define this as long if you want to get minimum CPU access time.
End Type
'with the SignBit you can emulate both Int64 and UInt64 without changing the real sign bit in HighPart.
'but if you want to change it you can access it like this mySign = (myVar.HighPart And &H80000000)
'or turn on the sign bit using myVar.HighPart = (myVar.HighPart Or &H80000000)
Public Function CInt64(ByVal vCur As Currency) As Int64
vCur = (CCur(vCur) * 0.0001#)
Call CopyMemory(CInt64, vCur, SIZEOF_INT64)
End Function
Now you can simply use CInt64 to create an Int64 number.
ex:
myRetVal = Win32APIFunctionWithOneInt64Param(CInt64(10000000))
'----OR
Dim myNum As Int64
myNum = CInt64(10000000)
And for more operations:
Public Sub Op_Ev(Dest As Int64, Src As Int64) 'for setting the value.
Call CopyMemory(Dest, Src, SIZEOF_INT64)
End Sub
Public Function Op_Eq(V1 As Int64, V2 As Int64) As Boolean 'for equal comparison.
Op_Eq = (V1.LowPart = V2.LowPart) : If Not Op_Eq Then Exit Function
Op_Eq = (V1.HighPart = V2.HighPart)
End Function
Public Function Op_Gr(V1 As Int64, V2 As Int64, Optional ByVal IsUnsignedComparison As Boolean = False) As Boolean 'for grater comparison.
If IsUnsignedComparison Then
Dim H1 As Long, H2 As Long 'don't change the location of these definitions to optimize the function to prevent to execute two or more {SUB ESP, 4}
H1 = (V1.HighPart And &H7FFFFFFF) : H2 = (V2.HighPart And &H7FFFFFFF)
Op_Gr = (H1 > H2) : If (H1 <> H2) Then Exit Function
Dim HBS1 As Long, HBS2 As Long 'don't change the type of these two vars to byte to keep alignment for local variables.
HBS1 = ((V1.HighPart And &H80000000) / &H80000000) 'export the sign bit and shift it to the right.
HBS2 = ((V2.HighPart And &H80000000) / &H80000000) 'export the sign bit and shift it to the right.
Op_Gr = (HBS1 > HBS2) : If (HBS1 <> HBS2) Then Exit Function
Else
Op_Gr = (V1.HighPart > V2.HighPart) : If (V1.HighPart <> V2.HighPart) Then Exit Function
End If
Op_Gr = (V1.LowPart > V2.LowPart)
End Function
Public Function Op_Ls(V1 As Int64, V2 As Int64, Optional ByVal IsUnsignedComparison As Boolean = False) As Boolean 'for less comparison.
If IsUnsignedComparison Then
Dim H1 As Long, H2 As Long 'don't change the location of these definitions to optimize the function to prevent to execute two or more {SUB ESP, 4}
H1 = (V1.HighPart And &H7FFFFFFF) : H2 = (V2.HighPart And &H7FFFFFFF)
Op_Ls = (H1 < H2) : If (H1 <> H2) Then Exit Function
Dim HBS1 As Long, HBS2 As Long 'don't change the type of these two vars to byte to keep alignment for local variables.
HBS1 = ((V1.HighPart And &H80000000) / &H80000000) 'export the sign bit and shift it to the right.
HBS2 = ((V2.HighPart And &H80000000) / &H80000000) 'export the sign bit and shift it to the right.
Op_Ls = (HBS1 < HBS2) : If (HBS1 <> HBS2) Then Exit Function
Else
Op_Ls = (V1.HighPart < V2.HighPart) : If (V1.HighPart <> V2.HighPart) Then Exit Function
End If
Op_Ls = (V1.LowPart < V2.LowPart)
End Function
Public Function Op_Cmp(V1 As Int64, V2 As Int64, Optional ByVal IsUnsignedComparison As Boolean = False) As Long 'for comparison.
If Op_Gr(V1, V2, IsUnsignedComparison) Then
Op_Cmp = 1
ElseIf Op_Ls(V1, V2, IsUnsignedComparison) Then
Op_Cmp = -1
Else
Op_Cmp = 0
End If
End Function