Thread: Send a numeric

  1. #1
    Registered User
    Join Date
    Nov 2006

    Send a numeric

    Hi to all,

    I need to send from server to client a numeric information. If the info is a string, I write
    send(newsocketfd, MyMsg, sizeof(MyMsg),0);

    If is numeric how can send the value? for example:
    "The number of students are: " 10

    Thank You and Best Regards

  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    Send the string "10" ?
    It's simple to implement, portable, and easy to trace using network debug tools.

    You could do
    send( newsocketfd, &myInt, sizeof(MyInt),0);
    but there's a whole "can-o-worms" of potential problems with that, like what endian the machines use and how big an int is.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  3. #3
    int x = *((int *) NULL); Cactus_Hugger's Avatar
    Join Date
    Jul 2003
    Banks of the River Styx
    typedef's can help with the size issue. Setup a header with some #ifdef's to select the appropriate size on each platform you need to compile for. (There are a couple in stdint.h which is available on many systems - uint8_t, uint16_t, etc.)

    After you've got size accounted for, there are some functions to help with endianness: htons() and htonl(), ntohs(), ntohl(). (Host-to-Network-short/long and Network-to-Host-short/long) So, on the sending size, use htons/l() and on the recv'ing side use ntohs/l(). See the man pages for more info.

    As Salem partially hints, your question is vague as to how you intend to send your data. You can either send 10 in binary (using either 2 or 4 bytes) or you can send the text "10". Which are you trying to accomplish?
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