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    <pre><code>extern "C" __declspec(dllexport) LPSTR Get_GetDescription(HANDLE) </code></pre> <p>Returning a pointer like this is rather dangerous, as it is not clear who owns the memory and thus who should take responsibility for freeing it.</p> <p>It would be safer to create the buffer in your VB code and pass it into the DLL where the value can be memcpy'ed in. So we could rewrite the C++ side like:</p> <pre><code>extern "C" __declspec(dllexport) void Get_GetDescription(HANDLE, LPSTR) void Get_GetDescription(HANDLE resultBreakDown, LPSTR buffer){ memcpy(buffer, ((CalcBreakDown*)resultBreakDown)-&gt;GetDescription().c_str(), ((CalcBreakDown*)resultBreakDown)-&gt;GetDescription().length()+1); } </code></pre> <p>And then redo the VB code as follows:</p> <pre><code>&lt;DllImport("FeeEngineDll.dll", CharSet:=CharSet.Ansi, CallingConvention:=CallingConvention.Cdecl)&gt; _ Public Shared Sub Get_GetDescription(ByVal resultBreakDown As IntPtr, &lt;MarshalAs(UnmanagedType.LPStr)&gt; ByVal szFilename As StringBuilder) End Sub </code></pre> <p>I have added <code>CharSet:=CharSet.Ansi</code> to the DllImport. Your C++ code is not using unicode characters, whereas VB probably will be, so best specify that, you probably don't need to put it in but I like to make these things explicit.</p> <p>Note the use of <code>StringBuilder</code> instead of <code>String</code> as strings are immutable in VB. Finally, you will need to be careful to allocate enough space in your string builder for the description:</p> <pre><code>Dim buffer As StringBuilder = New StringBuilder(512) </code></pre> <p>You can either do this by using a large number in your VB code, as I have just done. This will however, cause problems if your C++ code ever copies more characters than you allocated.</p> <p>Other better options would either be to pass in the buffer size to the C++ code so that it knows how much it is allowed to write, or to have a get size function in the C++ code that can be used to determine how much space should be allocated for the buffer.</p>
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    1. POreturn string from c++ function to VB .Net
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    1. CO..Thanks a lot for detailed insight to a question...I can also write a code in unmanaged c++ to free the memory for eg.Void FreeUmanagedString(void* p){delete[]p;}.....and call this function from my VB.Net code....this approach is better or the approach you have mentioned in your answer is better.
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    2. COI would still very much favour the approach I outlined. As Hans pointed out in his comment on the question there are other potential pit falls with allocating memory in a DLL and using it else where.
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    3. CO...i have used your approach ....but one problem is coming...uneven characters are coming in the extra space of buffer....when i am showing the text returned from the unmanaged code
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