vb.net用DllImport调用外部dll，的写法

[lutaiyk]

extern "C" __declspec(dllexport) int SendShortMessage(char *Number, int NumberLen, char *Message, int MessageLen)
这个是Dll中的function。

我是这样在vb.net中调用的
<DllImport("SMS.dll", CharSet:=CharSet.Unicode, SetLastError:=True)> Private Shared Function SendShortMessage(ByVal Fnumber() As Char, ByVal NumberLen As Integer, ByVal FMessage() As Char, ByVal MessageLen As Integer) As Integer

<DllImport("SMS.dll", CharSet:=CharSet.Unicode, SetLastError:=True)> Private Shared Function SendShortMessage(ByVal Fnumber As String, ByVal NumberLen As Integer, ByVal FMessage As String, ByVal MessageLen As Integer) As Integer

用这两种方法都可以调用，但是number好像就不能正确的得到，请问该怎么写？

多谢指教！

[鸭梨山大帝]

Declare Function SendShortMessage Lib "SMS.dll" Alias "SendShortMessage" (ByVal Fnumber  As StringBuilder, ByVal NumberLen As Integer, ByVal FMessage As StringBuilder, ByVal MessageLen As Integer) As Integer 

[lutaiyk]

用您的办法StringBuilder 报错

[lzsh0622]

试试:

ByVal NumberLen As Integer --> ByVal NumberLen As Int16
ByVal MessageLen As Integer --> ByVal MessageLen As Int16

As Integer --> As Int16

[wuyq11]

最后一个参数声明成IntPtr
http://topic.csdn.net/u/20090225/15/a6bc50ad-9721-4749-b189-dc4a4bc045a1.html

[鸭梨山大帝]

Imports System.Text;

如果Imports了,还报错,贴出一下错误提示

[lutaiyk]

我觉得问题是出在char *Number这个参数的地方，ByVal NumberLen As Integer可能没问题


Lost_Painting，添加Imports System.Text; 是不报错了
可是我应该怎样调用那？
下面是我原来的调用方式。
Dim aa1 As String

Dim bb
aa1 = TextBox2.Text

Label1.Text = SendShortMessage("13920002000", 11, aa1, aa1.Length)

[鸭梨山大帝]

一样的调用
只是需要多申明两个StringBuilder.

[lutaiyk]

没有抱错，但出不来结果

[wild_wolf99]

引用 1 楼 lost_painting 的回复:

VB.NET codeDeclareFunction SendShortMessageLib"SMS.dll"Alias"SendShortMessage" (ByVal FnumberAs StringBuilder,ByVal NumberLenAsInteger,ByVal FMessageAs StringBuilder,ByVal MessageLenAsInteger)AsIntege?-

这样写没问题，和在VB6中的写法一样的

[cnzdgs]

你要先确定Number和Message是输入参数还是输出参数，如果是输入，用String即可；如果是输出，则用StringBuilder，并给出足够的长度（NumberLen、MessageLen参数），这两个参数用Integer没错。