Beej's Guide to Network Programming Using Internet Sockets

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Beej’s Guide to Network Programming Using Internet Sockets 458.4. close()Close a socket descriptorPrototypes#include int close(int s);DescriptionAfter you’ve finished using the socket for whatever demented scheme you have concocted andyou don’t want to send() or recv() or, indeed, do anything else at all with the socket, you canclose() it, and it’ll be freed up, never to be used again.The remote side can tell if this happens one of two ways. One: if the remote side calls recv(),it will return 0. Two: if the remote side calls send(), it’ll recieve a signal SIGPIPE and send()will return -1 and errno will be set to EPIPE.Windows users: the function you need to use is called closesocket(), not close(). Ifyou try to use close() on a socket descriptor, it’s possible Windows will get angry... And youwouldn’t like it when it’s angry.Return ValueReturns zero on success, or -1 on error (and errno will be set accordingly.)Examples = socket(PF_INET, SOCK_DGRAM, 0);.// a whole lotta stuff...*BRRRONNNN!*.close(s); // not much to it, really.See Alsosocket(), shutdown()
Beej’s Guide to Network Programming Using Internet Sockets 468.5. gethostname()Returns the name of the systemPrototypes#include int gethostname(char *name, size_t len);DescriptionYour system has a name. They all do. This is a slightly more Unixy thing than the rest of thenetworky stuff we’ve been talking about, but it still has its uses.For instance, you can get your host name, and then call gethostbyname() to find out your IPaddress.The parameter name should point to a buffer that will hold the host name, and len is the sizeof that buffer in bytes. gethostname() won’t overwrite the end of the buffer (it might return anerror, or it might just stop writing), and it will NUL-terminate the string if there’s room for it in thebuffer.Return ValueReturns zero on success, or -1 on error (and errno will be set accordingly.)Examplechar hostname[128];gethostname(hostname, sizeof(hostname));printf("My hostname: %s\n", hostname);See Alsogethostbyname()
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Beej's Guide to Network Programming Using Internet Sockets

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