int SCTPSock = socket(PF_INET, SOCK_SEQ_PACKET, IPPROTO_SCTP);

void* pvSockAddrs;
int nAddrCount = 2;
pvSockAddrs = malloc( nAddrCount*sizeof(sockaddr_in));

//create addrs
struct sockaddr_in* sa;
sa = (sockaddr_in*)pvSockAddrs;
sa->sin_family = AF_INET;
 ...

sa = (sockaddr_in*)(pvSockAddrs + sizeof(sockaddr_in));
 ...
int nRet = sctp_bindx(SCTPSock, pvSockAddrs, nAddrCount, SCTP_BINDX_ADD_ADDR);

Example 3: Using sctp_bindx() to bind to multiple IP addresses.