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Hi every body,
I'm working on Winform project in C# and I have to use a C written dll to communicate with an OpenVMS machine.

Some methods are using a C char** or an unsigned char** parameters

When i try to "translate" those parameters in string array, byte array or a StringBuilder and call thoses methods my software threw an AccesViolation.

I have the same problem when I replace thoses parameters with an IntPtr and use Marshal.Copy();

My software is build with the unsafe option.

Here an extract from the sources :

[DllImport("IPSecureClt.dll", EntryPoint = "IPSec_ListProjet")]
public static extern int IPSec_ListProject(
[In][Out][MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPTStr)]
ref string[] cListProjects,int iNbElement, ref int iNbProjects);

Here the C declaration :

long IPSec_ListProjet(char cList[][256+1], const unsigned long lNbElement, unsigned long *lNbProjets);

How could I convert the "C" char** to a "C#" string array ?

Thanks for helping
Richard MacCutchan 23-Jan-15 10:17am    
cList is a 2-dimensional byte array, not an array of strings.
clemhindie 26-Jan-15 2:58am    
Hi Richard,
I try to use a 2-dimensional byte instead of of a string array. The framework throw a MarchalDirectiveException.
Richard MacCutchan 26-Jan-15 4:06am    
See for details of how to use such a feature.

1 solution

Take a look on my article and code Calling All Stations. It handles the stuff converting C++ and C# strings and function calling between the runtimes.
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