高手请进vb调用c写的dll问题
vb6.0
activeX dll控件
用处：在jsp页面中用javascript调用.
类模块代码：(声明为long的，在c++写的dll里面是int型的，String在dll中是指针类型的，不知对不？？？？？？)
Private Declare Function ykt_opencard Lib "c:\windows\system32\YKTClient.dll " (ByVal nDeviceType As Long, ByVal nCom As Long, ByVal nBaud As Long, pRegion As String, pErrmsg As String) As Long
Private Declare Function ykt_readopeninitcardno Lib "c:\windows\system32\YKTClient.dll " (pRegion As String, pDeptid As String, pDeptpass As String, pCardno As String, pCardtype As String, pErrmsg As String) As Long
Private Declare Function ykt_closecard Lib "c:\windows\system32\YKTClient.dll " (pErrmsg As String) As Long
'这个模块是个类模块，为什么上面的语名不能声明为public,在网上看到的例子都是声明为public的？？？？？？？？？？？？？
'目前提示找不到YKTClient.dll文件，不加路径也一样，dll放在system32目录下????????????????
'编写activeX dll，然后在网页上调用。是不是代码写在类模块里面，还是模块里面，（初学者，望高手指教）
Public cardno As String
Public Function openCard() As Long
Dim nDeviceType As Long
Dim nCom As Long
Dim nBaud As Long
Dim pRegion As String
Dim pDeptid As String
Dim pDeptpass As String
Dim pCardno As String
Dim pCardtype As String
Dim pErrmsg As String
Dim flag As Long
nDeviceType = 10
nCom = 9
nBaud = 1
pRegion = "XM "
pErrmsg = " "
flag = ykt_opencard(nDeviceType, nCom, nBaud, pRegion, pErrmsg)
End Function
Public Function readCard() As Long
Dim pRegion As String
Dim pDeptid As String
Dim pDeptpass As String
Dim pCardno As String
Dim pCardtype As String
Dim pErrmsg As String
Dim flag As Long
flag = openCard()
If flag = 0 Then
pRegion = "XM "
pDeptid = "0606 "
pDeptpass = "11111111 "
pCardno = " "
pCardtype = " "
pErrmsg = " "
flag = ykt_readopeninitcardno(pRegion, pDeptid, pDeptpass, pCardno, pCardtype, pErrmsg)
If flag = 0 Then
cardno = pCardno
flag = closeCard()
Else
flag = closeCard()
End If
End If
End Function
Public Function closeCard() As Long
Dim pErrmsg As String
Dim flag As Long
pErrmsg = " "
flag = ykt_closecard(pErrmsg)
End Function
[解决办法]
如果C中String是指针类型的话，在VB中String也要定义为ByVal，因为VB中String是指针存储的。
