c# - Cannot marshal 'parameter #': Internal limitation: structure is too complex or too large -

i have dll developed in c++. need use c#.

[structlayout(layoutkind.sequential, size = 205004, pack = 1)]     private struct mylist     {         public uint32 count;         [marshalas(unmanagedtype.byvalarray, sizeconst = 100)]         public mystruct[] info;     }; 

"mystruct" has of size 2050. calling dll method as

[dllimport("dllname.dll" callingconvention = callingconvention.cdecl)] private static extern uint32 getmylist(out mylist list); 

i error when call dll method. "cannot marshal 'parameter #1': internal limitation: structure complex or large."

do 1 have solution not changing c++ dll parts?

as error says, structure large marshalled way. have find approach.

it make more sense, in view, return structs 1 @ time. avoid needing hard code upper limit of there being no more 100 structs in list.

so write this:

c++

int getlistcount() {     return count; }  int getlistitem(int index, mystruct* item) {     if (index < 0)         return -1;     if (index >= count)         return -1;     *item = items[index];     return 0; } 

c#

[dllimport("dllname.dll" callingconvention = callingconvention.cdecl)] private static extern int getlistcount();  [dllimport("dllname.dll" callingconvention = callingconvention.cdecl)] private static extern int getlistitem(int index, out mystruct item);  ....  int count = getlistcount(); mystruct[] items = new mystruct[count]; (int index = 0; index < count; index++) {     int retval = getlistitem(out items[index]);     if (retval != 0)         // handle error } 

if cannot change dll faced performing marshalling hand. go this:

[dllimport("dllname.dll" callingconvention = callingconvention.cdecl)] private static extern uint32 getmylist(intptr listptr);  ....  intptr listptr = marshal.allochglobal(205004); // argh! magic constant alert try {     int retval = getmylist(listptr);     // presumably expected retval     int count = marshal.readint32(listptr);     mystruct[] items = new mystruct[count];     (int index = 0; index < count; index++)     {         intptr itemptr = listptr + 4 + index*2050; // more magic constants!         items[index] = (mystruct)marshal.ptrtostructure(itemptr, typeof(mystruct));     }  } {     marshal.freehglobal(listptr); } 

you might prefer use marshal.sizeof rather magic constants.