about operators

This is a discussion on about operators within the C++ Programming forums, part of the General Programming Boards category; I've created a class (Array) and i added the operator [] to get a specified element from the array. i ...

  1. #1
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    about operators

    I've created a class (Array) and i added the operator [] to get a specified element from the array.
    i also want to add the operator = to create\change an element i get from the [] operator, like that:
    Code:
    Array<int> arr;
    arr[0] = 7;
    how can i do it?

  2. #2
    & the hat of GPL slaying Thantos's Avatar
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    The assignment operator (operator =) would be so you could do this:
    Code:
    Array<int> bob = {1,3,5,6};
    Array<int> joe;
    joe = bob;
    When you have
    bob[0] = 7
    then that = is taken care of by int

    Just make sure that operator[] returns a reference and you'll be set.

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    i don't understand how to do it, coz the assignment operator takes Array type value by default, right? so why should he be applied to a reference?

  4. #4
    & the hat of GPL slaying Thantos's Avatar
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    What you showed in your example was not assigning one Array to another but assigning an int to a member inside of the Array.
    So by having operator[] return a reference to the object it can be used as a l-value.

    If you have a operator= for the Array class then that will take in a const Array reference and basically copy the given array like I showd in joe = bob;

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    but if i want to create new elements that way? i can use this only for modifying existing elements, but not for creating new ones..
    besides, i still didn't understand how to do what u said, could u give me code example for the operators plz?

  6. #6
    & the hat of GPL slaying Thantos's Avatar
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    To add elements you'll need to write an insert method. You can't really create "new" elements using operator[] as the object has to already exist.

    Have a look at the interface for a vector which is basically a resizable array
    http://www.cppreference.com/cppvector/

  7. #7
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    i decided i don't want it to assign new elements, so thanks for ur help =)

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