accessing an array of structures

This is a discussion on accessing an array of structures within the C Programming forums, part of the General Programming Boards category; Hi, i am having trouble figuring out how to access the other elements of an array of structures that is ...

  1. #1
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    accessing an array of structures

    Hi,

    i am having trouble figuring out how to access the other elements of an array of structures that is returned by a function called sg_get_network_iface_stats .

    As is noted below, the function returns a pointer to the first element in an array.. which i can access fine. How do i access the other elements though, as i dont seem to have a handle on the actual array, only a pointer to the first element within it...
    .. I think trying to learn C is making me more dumbererrr, as the solution is probably simple :-(



    sg_network_iface_stats *sg_get_network_iface_stats( entries);
    int * entries;

    Description
    The sg_get_network_iface_stats function takes a pointer to an int, entries, which is filled with the number of network interfaces the machine has. This is needed to know how many sg_network_iface_stats structures have been returned. A pointer is returned to the first sg_network_iface_stats.

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    C++ Witch laserlight's Avatar
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    Try accessing it as you would an array. After all, returning an array means returning a pointer to its first element.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    I have;

    ...
    sg_network_iface_stats p4;
    p4 = *sg_get_network_iface_stats(entries);

    With this i can use p4 to retrieve all of the structures info, eg: 'p4.speed'. Do you mean trying p4[1].speed ? I get this error attempting that;

    start.c: In function 'main':
    start.c:32: error: subscripted value is neither array nor pointer

  4. #4
    C++ Witch laserlight's Avatar
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    With this i can use p4 to retrieve all of the structures info, eg: 'p4.speed'. Do you mean trying p4[1].speed ?
    No, since p4 is a struct, not an array. Rather:
    Code:
    sg_network_iface_stats *p = sg_get_network_iface_stats(entries);
    Now you access p[0].speed, p[1].speed etc.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    !! ahh nice, ! it works. thanks for the help!!

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