在线求救dll问题，请各位大哥帮忙(20分)

dll源码：<br>unit Unit1;<br><br>interface<br><br>uses<br> &nbsp;sysutils, windows, dialogs;<br><br>function MessageLook(sss: string): string; stdcall;<br><br>implementation<br><br>function MessageLook(sss: string): string; stdcall;<br>var<br> &nbsp;s: PCHar;<br>begin<br> &nbsp;Result := 'zhangqiujunDll!';<br> &nbsp;//Strcopy(PChar(p), s);<br> &nbsp;//Result := True; //<br> &nbsp;//showmessage(Result);<br> &nbsp;//Result := 5;<br>end;<br><br>end.<br><br><br><br>以下是调用过程：<br><br>implementation<br><br>uses<br> &nbsp;unit2;<br><br>{$R *.dfm}<br>var<br> &nbsp;DLLHandle: THandle;<br>//var<br>type<br> &nbsp;TMessageLook = function(s: string): string;<br>var<br> &nbsp;MessageLook: TMessageLook;<br>procedure LoadDLL;<br>var<br> &nbsp;str: string;<br>begin<br> &nbsp;try<br> &nbsp; &nbsp;DLLHandle := LoadLibrary('Project2.dll');<br> &nbsp; &nbsp;if DLLHandle &gt;= 32 then<br> &nbsp; &nbsp;begin<br> &nbsp; &nbsp; &nbsp;@MessageLook := GetProcAddress(DLLHandle,'MessageLook');<br> &nbsp; &nbsp; &nbsp;Assert(@MessageLook &lt;&gt; nil);<br> &nbsp; &nbsp; &nbsp;str := Form1.edit1.text;<br> &nbsp; &nbsp; &nbsp;str := MessageLook(str);<br> &nbsp; &nbsp; &nbsp;//str := p[1];<br> &nbsp; &nbsp; &nbsp;showmessage(str);<br> &nbsp; &nbsp;end;<br> &nbsp;finally<br> &nbsp; &nbsp;//FreeLibrary(DLLHandle);<br> &nbsp;end;<br>end;<br><br><br>请高手指点为什么不能访问MessageLook函数？

两个问题：第一最好参数不要string,如果用string则必须应用单元叫什么sharmm好像，<br>第二：既然上面都stdcall;<br>TMessageLook = function(s: string): string;没有stdcall?

错了，是delphimm

返回值最好是pchar类型

留个mail给你个示例

传入和返回值最好用pchar或char array

terryapp大哥，我的mail： qiujun.zhang@kingstargroup.com

我刚开始用pchar不行，然后换string了，还是同样的错误。

没有export怎么访问

这个有的，没贴出来，dll加载成功了，就是函数访问后报Invalid pointer operation!

收邮件。。。

1.不要用string类型<br>2.不要用PChar参数做为返回值,而应该做为输出参数传入DLL,并应该由EXE负责分配并释放内存空间<br>你的函数应该改为<br>function MessageLook(<br> &nbsp;sss: pchar;<br> &nbsp;sResult : pchar;<br> &nbsp;iResultLength : integer<br> &nbsp: boolean; stdcall;

.dll中<br>function MessageLook(sss: string): string; stdcall;<br>调用时<br>TMessageLook = function(s: string): string;//在这加 stdcall;<br>还有不知道你在dll的project中<br>exports MessageLook;写了没有

把你的工程文件打开,改成这样:<br>program (你的工程名);<br><br>uses<br> &nbsp;sharemem,//这个很重要<br> &nbsp;Forms,...<br>再把你的DLL文件打开,改成这样:<br>library (你的DLL工程名);<br>uses<br> &nbsp;sharemem,//这个同样很重要<br> &nbsp;SysUtils,<br> &nbsp;Classes;<br><br><br>还有我觉得你的DLL源码不太正宗,有这样的 unit Unit1;??<br>应是library (你的DLL工程名);吧,个人意见,呵呵

terryapp大哥，很谢谢你啊，不过我的dll函数中如果按照输入参数<br>function MessageLook(sss: string): string; stdcall;<br>begin<br> &nbsp;Result := 'zhangqiujunDll!';<br>end;<br><br>报错：Invalid pointer operation! <br><br>但是以下就正确了，<br>function MessageLook(sss: string): string; stdcall;<br>begin<br> &nbsp;Result := sss;<br>end;<br><br>谁可以解释下啊

lkjx2007,大哥，你真牛，谢谢了啊<br>用你的方法，好了！<br>哈哈

不客气,呵呵,以前我也有这情况的,

在建一个dll时，你先看头上有一段说明，<br>就是你要的答案！<br>{ Important note about DLL memory management: ShareMem must be the<br> &nbsp;first unit in your library's USES clause AND your project's (select<br> &nbsp;Project-View Source) USES clause if your DLL exports any procedures or<br> &nbsp;functions that pass strings as parameters or function results. This<br> &nbsp;applies to all strings passed to and from your DLL--even those that<br> &nbsp;are nested in records and classes. ShareMem is the interface unit to<br> &nbsp;the BORLNDMM.DLL shared memory manager, which must be deployed along<br> &nbsp;with your DLL. To avoid using BORLNDMM.DLL, pass string information<br> &nbsp;using PChar or ShortString parameters. }

多人接受答案了。