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POPassing C# structure with string array to c++ function which accepts void * for c# structure and char** for c# string array
 

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  1. POPassing C# structure with string array to c++ function which accepts void * for c# structure and char** for c# string array
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    <p>I want to send a <strong>C# structure with string array to a C++ function</strong> which accepts void * for the c# structure and char** for the c# structure string array member.</p> <p>I was able to send the structure to c++ function,but the issue is , <strong>not able to access the string array data member of c# structure from c++ function</strong>. When sending the string array separately,i was able to access the array elements.</p> <p>Sample code is-</p> <pre><code>C# Code: [StructLayout(LayoutKind.Sequential)] public struct TestInfo { public int TestId; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)] public String[] Parameters; } [DllImport("TestAPI.dll", CallingConvention = CallingConvention.StdCall, EntryPoint "TestAPI")] private static extern void TestAPI(ref TestInfo data); static unsafe void Main(string[] args) { TestInfo testinfoObj = new TestInfo(); testinfoObj.TestId = 1; List&lt;string&gt; names = new List&lt;string&gt;(); names.Add("first"); names.Add("second"); names.Add("third"); testinfoObj.Parameters=names.ToArray(); TestAPI(ref testinfoObj); } VC++ Code: /*Structure with details for TestInfo*/ typedef struct TestInfo { int TestId; char **Parameters; }TestInfo_t; //c++ function __declspec(dllexport) int TestAPI(void *data) { TestInfo *cmd_data_ptr= NULL; cmd_data_ptr = (TestInfo) data; printf("ID is %d \r\n",cmd_data_ptr-&gt;TestId);//Working fine for(i = 0; i &lt; 3; i++) printf("value: %s \r\n",((char *)cmd_data_ptr-&gt;Parameters)[i]);/*Error-Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt*/ } </code></pre> <p>When analyzing the memory stack, it is observed that,when i print ((char *)cmd_data_ptr->Parameters), the first array element("first") is getting printed, but using ((char *)cmd_data_ptr->Parameters)[i], not able access elements and above mentioned exception is coming.</p> <p>The structure memory address contains address of all the structure elements,but while accessing the data from c++,it is accessing only the first element of the string array.</p>
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