Marshalling problem in Managed C++ Wrapper

[jjones7947]

Doing Managed C++ Wrapper in VS2008. Have a native defined data structure as follows:

class API TF_StringList
{
public:
  TF_StringList(const char* encoding = "cp_1252");
    
  ~TF_StringList();

  TF_String* first_string() const {return start_string;}
  TF_String* last_string() const {return end_string;}

  void insert(const TF_String& aString);
  void insert(const char* aString);  

  // If the length parameter is larger than the size of the string,
  // The behavior is uncertain.
  void insert(const tf_Byte* aString, size_t aByteLength);

  void clear();

  size_t size() const { return list_size; }

  char* character_encoding;

private:
  
  void set_first(TF_String* stringPtr) {start_string = stringPtr;}
  void set_last (TF_String* stringPtr) {end_string = stringPtr;}

  TF_String* start_string;
  TF_String* end_string;
  TF_String* curr_pos;
  size_t list_size;


  // Do not expose the copy constructor and the assignment operator.
  TF_StringList(const TF_StringList& tmp);
  TF_StringList& operator=(const TF_StringList& tmp);

};

In one of my managed functions I have parameter of List<String^> categoryList and I want to load an object of type TF_StringList with the elements of that parameter.

//Instantiate the TF_StringList 
categories = new TF_StringList(); 
for(int i=0; i<categoryList.Count; i++) 
{ 
   const char* str = (const char*)(Marshal::StringToHGlobalAnsi(categoryList[i])).ToPointer(); 
   categories->insert(str); 
}

On the last line, I get the error:C2663: 'TF_StringList::insert' : 3 overloads have no legal conversion for 'this' pointer
First, The error would lead me to believe that str is not "seen" by the TF_StringList instance as a const char* since the insert(const char* aString) does not accept it.

Second, the list does not index out a Managed String (e.g. that String^ st = categoryList[i] is not valid). This seems unlikely since the declaration is List categoryList.

How can I check to find out what the problem actually is?

[Alex F]

C2663 is about const. What is categories variable declaratin? Please post the whole function.

[jjones7947]

The complete function so far is:

TFWrapper::TFWrapper(String^ mlexDir, String^ mlic, String^ mkey, List<String^> categoryList, Boolean^ m_useConj, String^ m_lang, String^ m_encoding)
{
	const char* c_lexDir = (char*)(Marshal::StringToHGlobalAnsi(mlexDir)).ToPointer();
	const char* c_lic = (char*)(Marshal::StringToHGlobalAnsi(mlic)).ToPointer();
	const char* c_key = (char*)(Marshal::StringToHGlobalAnsi(mkey)).ToPointer();
	finder = new TF_Finder(c_lexDir, c_lic, c_key);
	catalog = new TF_NameCatalog();
	categories = new TF_StringList();
	for(int i=0; i<categoryList.Count; i++)
	{
	    const char* str = (const char*)(Marshal::StringToHGlobalAnsi(categoryList[i])).ToPointer();
	    categories->insert(str);
	}
	customEntities = new TF_StringList();
	c_useConj = (bool*)Convert::ToBoolean(m_useConj);
}

[jjones7947]

Have read where the proper declaration for a parameter of a List of Managed Strings is

List<String^>^% categoryList

when I index into the list for an item, apparently the return is a String pointer:

String * mstr = categoryList[i];

Since I'm trying to make it acceptable to the insert method in the unmanaged dll:
Create the unmanaged class:

TF_StringList * categories = new TF_StringList();

Then convert mstr to a const char*

const char* str = (char*)(*void)Marshal::StringToHGlobalAnsi(mstr);

then pass str to the categories->insert(const char*);
Still get C2663 error

[jjones7947]

The problem here was that I had declared the List instance as const. The error is thrown because I'm trying to change a const object by inserting into it.

[Ajay Vijay]

String * mstr = categoryList[i];
const char* str = (char*)(*void)Marshal::StringToHGlobalAnsi(mstr);

Doesn't it should be:

const char* str = (char*)(*void)Marshal::StringToHGlobalAnsi(*mstr);