How do I send the data in struct in UDP sendto in C++?
struct routingTable{
int numServers;
int numNeighbors;
int selfId,neighborNode[5];
int Cost[6][6];
};
routingTable selfRoutingTable;
sendto(listener_socket,<This is a char *> , strlen(my_message), 0, (struct sockaddr *)&nbaddr, sizeof(nbaddr)
sendto(listener_socket,<This is a char *> , strlen(my_message), 0, (struct sockaddr *)&nbaddr, sizeof(nbaddr)
No it's not, it's a const void *. From a man page:
ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
const struct sockaddr *dest_addr, socklen_t addrlen);
Technically you could send your struct with: &selfRoutingTable and use sizeof for the size, but see below.
As EJP mentioned this is a pretty bad idea and you'll quickly run into issues with representations of the struct and its fields on different implementations (and you'll find out all about struct field padding and the like).
Look into a serialization mechanism (json, capnproto, protobufs, xml, asn.1 anything).
I now realize that "no it's not" is not always true. Apparently MSDN lists sendto as taking a const char *.
int sendto(
_In_ SOCKET s,
_In_ const char *buf,
_In_ int len,
_In_ int flags,
_In_ const struct sockaddr *to,
_In_ int tolen
);
The idea (of passing the pointer to whatever one wants) stands.
sizeofinstead ofstrlen(), but you should not do this. Don't use structs as network protocols.