Thread: Help with pointer syntax

  1. #1
    Registered User
    Join Date
    Feb 2009

    Help with pointer syntax

    I am trying to understand some socket code. One of the function calls is as follows:

    msgsock = accept(sock, (struct sockaddr *)0, (int *)0);
    Just wondering what the syntax for the last two arguments means and how it works.

    Thanks in advance.

  2. #2
    spurious conceit MK27's Avatar
    Join Date
    Jul 2008
    segmentation fault
    In this example, you are saying accept a connection on sock and you are not collecting any information about who that is (since the destination address for the last two arguments is 0). It might be a better practice to just use NULL here, if accept() will accept that.

    The reason you might need to cast zero would be that accept() expects a pointer of some specific sort.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
    Registered User
    Join Date
    Oct 2008
    both are NULL pointers cast to the proper type

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