VB6 中的 C++ 代码翻译

Question

我有一个 C dll，我想在 vb6 中使用它，这里是 C 语法：

#ifndef _MSC_VER
typedef long long INT64T;
#else
typedef __int64 INT64T;
#endif

int Init(int opts, void *key, INT64T offs);

我已将其转换为 VB6：

Public Declare Function Init Lib "x.dll" (ByVal opts As Integer, ByVal key As Long, ByVal offs As Currency)

然后调用它：

Init 0, 0, 0

函数的某些部分被执行并且我得到了这个错误：

错误的 DLL 调用约定

请您告诉我有什么问题吗？该dll来自第三方dll，所以我对此一无所知，

Answer 1

对于 64 位，您应该使用：

Type ULARGE_INTEGER
  LowPart As Long
  HighPart As Long
End Type

你的声明应该是这样的：

Public Declare Function Init Lib "x.dll" (ByVal opts As Long, ByVal key As Long, ByVal offs As ULARGE_INTEGER)

Public Declare Sub CopyMemory Lib "kernel32" (ByVal Destination As Long, ByVal Source As Long, ByVal Length As Long)

现在开始转换：

获得ULARGE_INTEGER 后，您可以将其翻译为Currency，如下所示：

' Copy int64 into the Currency data type
Dim curr as Currency
Dim int64 as ULARGE_INTEGER

' Copy ULARGE_INTEGER into the Currency data type
CopyMemory curr, int64, 8

' Multiply by 10000 to move Visual Basic decimal point to the end of the actual number
curr = curr * 10000

从Currency 遍历回ULARGE_INTEGER：

Dim curr as Currency
Dim int64 as ULARGE_INTEGER

' Devide by 10000 to move Visual Basic decimal point to original position
curr = curr * 0.00001       

' Copy Currency into the ULARGE_INTEGER data type
CopyMemory int64, curr, 8