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POCalling a DLL function with more than one return values
 

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  1. POCalling a DLL function with more than one return values
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    <p>My DLL might send more than one result/return value to exe in one shoot. I still don't understand how to make the callback function so DLL can communicate with host app. </p> <p>Here's the scenario :</p> <p>App :</p> <pre><code>type TCheckFile = function(const Filename, var Info, Status: string): Boolean; stdcall; var CheckFile: TCheckFile; DLLHandle: THandle; Procedure Test; var Info,Status : string; begin .... // load the DLL DLLHandle := LoadLibrary('test.dll'); if DLLHandle &lt;&gt; 0 then begin @CheckFile := GetProcAddress(DLLHandle, 'CheckFile'); if Assigned(CheckFile) then beep else exit; end; // use the function from DLL if Assigned(CheckFile) then begin if CheckFile(Filename, Info, Status) then begin AddtoListView(Filename, Info, Status); end; end; ... end; </code></pre> <p>DLL:</p> <pre><code>function CheckFile(const Filename, var Info,Status: string): Boolean; stdcall; var Info, Status: string; begin if IsTheRightFile(Filename, Info,Status) then begin result := true; exit; end else begin if IsZipFile then begin // call function to extract the file ExtractZip(Filaname); // check all extracted file for i := 0 to ExtractedFileList.count do begin IsTheRightFile(ExtractedFile, Info, Status) then // how to send the Filename, Info and Status to exe ?? // &lt;&lt; edited // SendIpcMessage('checkengine', pchar('◦test'), length('◦test') * SizeOf(char)); error! // "AddtoListView(Filename, Info);" ??? end; end; end; end; </code></pre> <p>Actually I still get an error from code above. So in my case, I need your help to explain and determine what is the correct way to send data from DLL to appp.</p>
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    1. COGetProcAddress(DLLHandle, 'CheckFile'); - does it return a valid handle? did not you forget to specify your dll funciton in IMPORTS section?
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    2. CODo you mean `Info` and `Status` instead of `Info` and `Filename`? Because `Filename` is `const` and can not be modiefied. To modify `Info` and `Status` you would need to set a value for it in your DLL function. Be aware that passing around strings can lead to problems if you do not use `ShareMem` in the `uses` clause.
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    3. CO@heximal : Yes it return a valid handle. I am sure there is no problem with importing/exporting function. I have tried to use dummy function in DLL.
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