C# pinvoke C char array -


marshalling char array.

the c typedef of function is:

typedef bool (*get_variableinfofunc)(int *, char * *, int *, int *);

it`s usage like:

pnvariableidarray = new (nothrow) int[numvars]; pcvariablename = new (nothrow) char*[numvars]; (int = 0; < numvars; i++) {     pcvariablename[i] = new char[100]; } pnunvariableidarray = new (nothrow) int[numvars]; pnvariabletype = new (nothrow) int[numvars]; res = get_variableinfo(pnvariableidarray, pcvariablename, pnunvariableidarray, pnvariabletype);

my c# signature is:

[dllimport(autodynresultsapidll, entrypoint = "get_variableinfo", setlasterror = true)] [return: marshalas(unmanagedtype.bool)] public static extern bool getvariableinfo(     int[] pnvariableidarray,     intptr[] pcvariablename,     int[] pnunvariableidarray,     int[] pnvariabletype);

i use like:

var stringpointers= new intptr[numvars]; (int = 0; < numvars; i++) {     by[i] = marshal.allochglobal(100); } getvariableinfo(pnvariableidarray, stringpointers, pnunvariableidarray, pnvariabletype);

and string with:

var strings = new string[numvars]; (int = 0; < numvars; i++) {     strings[i] = marshal.ptrtostringansi(by[i]); }

is there nicer way doing without freeing memory of pointer. copy char array string array?

first of all, few problems code stands:

  1. the calling convention cdecl, need include callingconvention = callingconvention.cdecl in attribute.
  2. you set setlasterror = true, unmanaged function surely not call setlasterror. if so, remove setlasterror = true.
  3. you call allochglobal there no matching call freehglobal, , memory leaked.
  4. your assumption no string exceed length of 100 (including null terminator) seems brittle, , @ risk of buffer overflow.

as far main body of question goes, marshaller won't marshal array of strings you. current approach, subject provisos above, correct way tackle problem.


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