函数SSC_RestoreVal是C++写的DLL里的函数.
//C++代码
//头文件定义
SSC_RestoreVal(const wchar_t* tag, unsigned char** value, unsigned long* valSize);
//函数应用
void RestoreValue()
{
BYTE* valueBuffer = NULL;
DWORD valueBufferSize = 0;
string val;
wstring tag;
wcout << L"Enter value tag name to restore: ";
getline(wcin, tag);
//restore saved value
SscRc rc = SSC_RestoreVal(tag.c_str(), &valueBuffer, &valueBufferSize);
if(S_SSCRC_OK(rc))
{
val.assign((const char*)valueBuffer, valueBufferSize);
wcout << tag <<L" value is: ";
cout << val << endl;
}
else
{
wcout << L"Unable to get requested value: " << rc << endl;
}
//free the buffer
SSC_SecureFreeValBuffer(valueBuffer, valueBufferSize);
valueBuffer = NULL;
return;
}
//VB代码
//函数定义
Public Declare Function SSC_RestoreVal Lib "SscApi.dll" (ByVal tag As String, ByVal Value As String, ByVal valSize As Long)
//应用
Private Sub A_RestoreV_Click()
Dim valueBuffer As String
Dim valueBufferSize As Long
Dim tag As String
Dim val As String
Dim rc As Enum_SscRc
On Error GoTo RestoreError
valueBufferSize = 0
valueBuffer = ""
tag = "abra"
rc = SSC_RestoreVal(tag, VarPtr(valueBuffer), VarPtr(valueBufferSize))
If (S_SSCRC_OK(rc)) Then
' val.assign valueBuffer, valueBufferSize
'CopyMemory val, valueBuffer, valueBufferSize
MsgBox tag & " Value is:" & valueBuffer
Else
MsgBox "Unable to get requested value: "
End If
txtReStoreValue.Text = "valueBuffer:" & CStr(valueBuffer) & " valueBufferSize:" & CStr(valueBufferSize) & " val:" & val
' SSC_SecureFreeValBuffer valueBuffer , valueBufferSize
RestoreError:
MsgBox Err.Description
End Sub
C++代码可正常运行并得到正确结果,但改写为VB后,能获取到值的长度(valueBufferSize),但获取不到值(即:valueBuffer="").
