Dllimport char* [] from C to C#

Question

How can I using Dllimport by C# to get string array from C library

int GetClasses (int *NumberofClasses, char *ClassNames[], int arrayLength)

I have try StringBuilder[] and many of MarshalAsAttributes to receive ClassNames but still not work and cause memory violation

I have only explanation of this C method is showing below.

int GetClasses(int * NumberofClasses, char * ClassNames[], int arrayLength)

This function will get the total number of unique classes and each unique class name.

Parameters:
NumberofClasses: Total number of unique classes.
ClassNames: Array of allocated char * to return class names.
arrayLength: Length of passed ClassNames array. If the result exceeds this array length, this function will fail with an error code.

Returns: Zero for success. Non-zero for error

And my declaration is

[DllImport(@".\library.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
private static extern Int16 GetClasses(ref UInt16 NumberofClasses, StringBuilder[]  ClassNames, UInt16 arrayLength);

I have pass

NumberofClasses=16,

ClassNames= StringBuilder[16] with 256 capacity of each

arrayLength=16

to this call

Answer 1

Finally I got the success call by modify the declaration of parameter type.

[DllImport(@".\library.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
    private static extern Int16 GetClasses(ref UInt16 NumberofClasses, [In][Out][MarshalAs(UnmanagedType.LPArray)] string[] ClassNames, UInt16 arrayLength);

And allocate a string array to parameter ClassNames

string[] names = new string[NumberOfClasses];

for (int i = 0; i < names.Length; i++)
{
    names[i] = new string(new char[256]);
}