c calls c++ method introduction window api

Example 1 is as follows:

// Declaration section 
[DllImport("um_web_client.dll")]
  private static extern int CheckUserName(string UserName);
//
public static int AuthUserName(string username)
  {
   if(!IsConnection())
   {
    StartWebClient(UDBClientIP,UDBClientPort,UDBClientTimeout);
   }
   return CheckUserName(username);
  }

However, if the c++ method USES Pointers or structs etc., the reference should be noted. The reference array or pointer should be used accordingly. Example 2:

Declaration section

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi )]
  public class tagPlayerInfoOut 
  {
   public int id;
   public String PlayerName;
   public int Country;
   public int OfficerRace;
   public int Level;
   public int MilitaryRank;
   public int Money;
   public int ResourceCount;
   public int CityCount;
   public int GeneralCount;
   public int Credit;
  }
  [ StructLayout( LayoutKind.Sequential )]
  public struct tagPlayerInfoOutEx 
  {
   public int id;
   public IntPtr PlayerName;
   public int Country;
   public int OfficerRace;
   public int Level;
   public int MilitaryRank;
   public int Money;
   public int ResourceCount;
   public int CityCount;
   public int GeneralCount;
   public int Credit;
  }
 
[DllImport("um_web_client.dll")]
  public static extern int GetPlayerListCs(int maxrows, out int rows,  out IntPtr playerlist);
  [DllImport("um_web_client.dll")]
  public static extern int GetPlayerListCs(int maxrows, out int rows, tagPlayerInfoOutEx** playerlist);

methods

public static DataTable UsingMarshal()
  {
   if(!IsConnection())
   {
    StartWebClient(UDBClientIP,UDBClientPort,UDBClientTimeout);
   }
   DataTable dt = new DataTable();
   dt.Columns.Add("id");
   dt.Columns.Add("PlayerName");
   dt.Columns.Add("Country");
   dt.Columns.Add("OfficerRace");
   dt.Columns.Add("Level");
   dt.Columns.Add("MilitaryRank");
   dt.Columns.Add("Money");
   dt.Columns.Add("ResourceCount");
   dt.Columns.Add("CityCount");
   dt.Columns.Add("GeneralCount");
   dt.Columns.Add("Credit");
   int size = 0;
   IntPtr outArray;
   GetPlayerListCs(20, out size, out outArray);
   tagPlayerInfoOut[] manArray = new tagPlayerInfoOut[size];
   IntPtr current = outArray;
   //Console.WriteLine(" Record number {0}",size);

   for( int i = 0; i < size; i++ )
   {
    manArray[ i ] = new tagPlayerInfoOut();
    Marshal.PtrToStructure(current, manArray[i]);
    Marshal.DestroyStructure(current, typeof(tagPlayerInfoOut) );
    current = (IntPtr)((long)current + Marshal.SizeOf(manArray[i]));
    dt.Rows.Add(new object[] {manArray[i].id,manArray[i].PlayerName,manArray[i].Country,manArray[i].OfficerRace,manArray[i].Level,manArray[i].MilitaryRank,manArray[i].Money,manArray[i].ResourceCount,manArray[i].CityCount,manArray[i].GeneralCount,manArray[i].Credit});
    dt.AcceptChanges();
   //Console.WriteLine( "Element {0}: {1} {2}", i, manArray[i].id, manArray[i].PlayerName);
  }
   Marshal.FreeCoTaskMem(outArray);
   return dt;
  }
  public static unsafe DataTable UsingUnsafe()
  {
   int size;
   if(!IsConnection())
   {
    StartWebClient(UDBClientIP,UDBClientPort,UDBClientTimeout);
   }
   DataTable dt = new DataTable();
   dt.Columns.Add("id");
   dt.Columns.Add("PlayerName");
   dt.Columns.Add("Country");
   dt.Columns.Add("OfficerRace");
   dt.Columns.Add("Level");
   dt.Columns.Add("MilitaryRank");
   dt.Columns.Add("Money");
   dt.Columns.Add("ResourceCount");
   dt.Columns.Add("CityCount");
   dt.Columns.Add("GeneralCount");
   dt.Columns.Add("Credit");
   tagPlayerInfoOutEx* pResult;
   GetPlayerListCs(20,  out size, &pResult );
   tagPlayerInfoOutEx* pCurrent = pResult;
   //Console.WriteLine(" Record number {0}",size);
   for( int i = 0; i < size; i++, pCurrent++ )
   {
    //Console.WriteLine( "Element {0}: {1} {2}", i, pCurrent->id ,Marshal.PtrToStringAnsi(pCurrent->PlayerName));
    //Marshal.FreeCoTaskMem(pCurrent->PlayerName );
    dt.Rows.Add(new object[] {pCurrent->id,pCurrent->PlayerName,pCurrent->Country,pCurrent->OfficerRace,pCurrent->Level,pCurrent->MilitaryRank,pCurrent->Money,pCurrent->ResourceCount,pCurrent->CityCount,pCurrent->GeneralCount,pCurrent->Credit});
    dt.AcceptChanges();
   }
   Marshal.FreeCoTaskMem((IntPtr)pResult );
   return dt;
  }