array decade pointers information

This is a discussion on array decade pointers information within the C++ Programming forums, part of the General Programming Boards category; Hi http://www.informit.com/guides/conte...eqNum=207&rl=1 here it writes: "Functions in C/C++ can't return or receive array arguments" Is this true? Can't we pass ...

  1. #1
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    array decade pointers information

    Hi
    http://www.informit.com/guides/conte...eqNum=207&rl=1 here it writes:
    "Functions in C/C++ can't return or receive array arguments"
    Is this true?
    Can't we pass array to function as value? Is it always pointer?

  2. #2
    and the hat of wrongness Salem's Avatar
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    That's normally true, yes.

    Arrays are not passed by value, always as a pointer (or maybe as a reference in C++)

    But if you embed your array inside a struct, then that would be passed by value, if you passed the containing struct by value.
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    When you pass an array as an argument, it decays to a pointer to its first element, so you are actually passing a pointer.
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  4. #4
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    Thank you.
    Here there is an information about passing array with value to func.
    http://www.informit.com/guides/conte...eqNum=241&rl=1
    Code:
    template <typename T, size_t size>
    
    void foo(T (&array)[size])
    {
     //sort array, find the sum, min, max, etc
    }
    Is this right?
    Can we use like this? I mean is this really pasing array to func by value?

  5. #5
    The larch
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    Seems right. If I understand templates right, size needs to be a compile-time constant, though.

  6. #6
    Frequently Quite Prolix dwks's Avatar
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    This demonstrates the same thing. It may be easier to understand.
    Code:
    void foo(int (&array)[size]) {
    }
    dwk

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  7. #7
    The larch
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    Does it? I get size is undefined? The trick with the template is that size is a compile time constant.

    Your approach would need magic constants both in the function and in the calling code, or the use of a global constant, define or something like that.

    I'll probably need to check the link, because I don't get why and where this would be useful...

    Edit: back. This is just a proof of concept...
    Last edited by anon; 05-02-2007 at 01:01 PM.

  8. #8
    "Why use dynamic memory?"
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    why pass array ?? as some said, you pass pointer to that array and then return the pointer
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  9. #9
    The larch
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    Well, the aim is that size is deducted from the passed array, so you don't need to pass it separately.

    However, this could be an example of "clever code", or a clever way to shoot yourself in the leg (the array has already decayed to pointer).

    Any C++ programmer would consider standard containers first

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