How to convert managed class to unmanaged char* in vc++.net

[selvialagar]

i'm new to vc++.net...I'm doing a project to send a packet to another machine like ping command...in this i'm using sendto() function..i have to convert all the class parametes to char*...
my code is ..

int	SendEchoRequest(SOCKET s, LPSOCKADDR_IN lpstToAddr)
	   {
		   ECHOREQUEST &echoreq=*new ECHOREQUEST;
		   static nID=1;
		   static nSeq=1;
		   int nRet;
		   echoreq.IcmpHDR->Type=ICMP_ECHOREQ;  
		   Console::WriteLine(S"Type :{0}",echoreq.IcmpHDR->Type.ToString());    
		   echoreq.IcmpHDR->Code=0; 
		   echoreq.IcmpHDR->Checksum=0;  
		   echoreq.IcmpHDR->ID=nID++;
		   echoreq.IcmpHDR->Seq_no=nSeq++;
		   for(nRet=0;nRet<REQ_DATASIZE;nRet++)
		   {
			   echoreq.Cdata[nRet]=' '+nRet;
		   }
		   echoreq.dwTime=GetTickCount();
		   const char *buffer;
		   int length;
		   System::Runtime::InteropServices::Marshal::Copy(echoreq,0,buffer,length);    
		   //echoreq->IcmpHDR->Checksum =in_cksum((unsigned short *)&echoreq,echoreq->ToString()->get_Length());
		   nRet=sendto(s,buffer,length,0,(LPSOCKADDR)lpstToAddr,sizeof(SOCKADDR_IN));
		   if (nRet == SOCKET_ERROR) 
		       ReportError("sendto()");
	        return (nRet);
	   }

i tried using marshall copy function but it wont work....what i'll do to correct this problem....

[Plater]

What do you need a char* for now? I didn't see any unamanaged code in there?

[Plater]

What do you need a char* for now? I didn't see any unamanaged code in there?
Was it that sendto() function? Why not just use .NET sockets?