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?