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POdllimport : c code affect a struct passed by reference (c#)
 

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  1. POdllimport : c code affect a struct passed by reference (c#)
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    <p>I've got a c dll that contains an exposed function, that takes three parameters : </p> <pre><code>int ParseInput(char* opt_path, char* input, SENNA_RESULT_ARRAY* result); </code></pre> <p>I want to call this from C#, which actually works. The problem is that the result struct is not affected. Here is the structure defined in c code : </p> <pre><code> typedef struct RESULT_ { char* word; int pos_start; int pos_end; char* pos; char* chk; char* ner; char* psg; } RESULT; typedef struct RESULT_ARRAY_ { int size; RESULT* Results; } RESULT_ARRAY; </code></pre> <p>and my c# code : </p> <pre><code>[StructLayout(LayoutKind.Sequential)] public struct SENNA_RESULT { [MarshalAs(UnmanagedType.LPStr)] public string word; [MarshalAs(UnmanagedType.I4)] public int pos_start; [MarshalAs(UnmanagedType.I4)] public int pos_end; [MarshalAs(UnmanagedType.LPStr)] public string pos; [MarshalAs(UnmanagedType.LPStr)] public string chk; [MarshalAs(UnmanagedType.LPStr)] public string ner; [MarshalAs(UnmanagedType.LPStr)] public string psg; } [StructLayout(LayoutKind.Sequential)] public struct SENNA_RESULT_ARRAY { public SENNA_RESULT[] Results; public int size; } [DllImport("Senna-32.dll", CharSet = CharSet.Ansi)] static extern int Parse(string msg, string stream, ref SENNA_RESULT_ARRAY results); Parse(@"path", "sentence", ref result_array) </code></pre> <p>I've tried many things, like : 1-use classes instead of struct without ref keyword 2-use a pointer instead of passing a struct</p> <p>Each time i got a different error like array is not of the specified type low level error( corrupted heap)</p> <p>even if i don't specify the array in the first struct, the size member has not the correct value (the C code prints the value in the console)</p> <p>Any advice ?</p> <p>Thanks</p>
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    1. USMorti
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      1. POdllimport : c code affect a struct passed by reference (c#)
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      1. VTUpMod
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      1. POdllimport : c code affect a struct passed by reference (c#)
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      1. VTUpMod
    1. COI can't speak with certainty, but I believe the correct syntax is `out SENNA_RESULT_ARRAY results`.
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      1. POdllimport : c code affect a struct passed by reference (c#)
      1. USMike Perrenoud
    2. COThe order of members is different, `size` is the first element in the C result array struct and the last in the C# result array struct. Aren't the orders supposed to be equal?
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      1. POdllimport : c code affect a struct passed by reference (c#)
      1. USKlas Lindbäck
    3. COThis function is almost impossible to use correctly from a C program, it doesn't get better when you do it from C#. There's a severe memory management problem, the array and all those strings need to be released again. That requires the caller to use the same memory allocator as the callee, never the case from C#, rarely the case from C.
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      1. POdllimport : c code affect a struct passed by reference (c#)
      1. USHans Passant
 

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