Can anyone help me write a code to overload [] operator?
There are bunch of books mentioning this for 1D array but I cannot
find one for multi-dimension array, and I am a novice in c++.
My problem is :

class XXX {
public:
 .........
private:
 char m[10][10];
}

I know if m were 1D array, then it should look like

 inline char& XXX::operator[](ind i) { return m[i];}

But in the case of 2D array, how can I overload [] operator?

Thanks in advance...

In article <CoMLwu.n2B@usenet.ucs.indiana.edu>, <bjin@silver.ucs.indiana.edu>
writes:
>
> Can anyone help me write a code to overload [] operator?
> There are bunch of books mentioning this for 1D array but I cannot
> find one for multi-dimension array, and I am a novice in c++.
> My problem is :
>
> class XXX {
> public:
>  .........
> private:
>  char m[10][10];
> }
>

I don't know what the standard says, but in current implementations of C++ like
C-SET++ and BCC, you can't.  Use the operator() instead, you can have an
arbitrary number of parameters.

Rodney

bjin@silver.ucs.indiana.edu (bong guk jin) writes:

>Can anyone help me write a code to overload [] operator?
>There are bunch of books mentioning this for 1D array but I cannot
>find one for multi-dimension array, and I am a novice in c++.
>My problem is :

>class XXX {
>public:
> .........
>private:
> char m[10][10];
>}

>I know if m were 1D array, then it should look like

> inline char& XXX::operator[](ind i) { return m[i];}

>But in the case of 2D array, how can I overload [] operator?

You have to define the output of XXX::operator[] to be something
that can be the first argument of a subscript construct.

Possibly, you may be able to return a pointer to the desired row
of your final return type.

If this is not feasible, you will have to define a class, just for
the purpose of acting as a temporary return value for the first
operator[] and as the base object for the second operator[].

This is getting to be FAQ.

In article <CoMLwu.n2B@usenet.ucs.indiana.edu>, bjin@silver.ucs.indiana.edu (bong guk jin) writes:
|> There are bunch of books mentioning this for 1D array but I cannot
|> find one for multi-dimension array, and I am a novice in c++.

There really isn't, at least not directly.

|> My problem is :
|>
|> class XXX {
|> public:
|>  .........
|> private:
|>  char m[10][10];
|> }
|>
|> I know if m were 1D array, then it should look like
|>
|>  inline char& XXX::operator[](ind i) { return m[i];}
|>
|> But in the case of 2D array, how can I overload [] operator?
|>
The closest you can come is:

class XXX_row {
public:
    friend class XXX
    char & operator [] (int j) { return ptr[j]; };
private:
    char *ptr;
    XXX_row(char *p): ptr(p) {};
};

class XXX {
public:
    XXX_row operator [] (int i) { return XXX_row(m[i]); };
    .......
private:
    char m[10][10];
};


That is, the operator[] for your class, XXX, must return an instance
of a proxy class that itself has an operator[] and refers to a
logical row in the original class.

--
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