Path: utzoo!attcan!uunet!cs.utexas.edu!rice!uw-beaver!sumax!ole!powell
From: powell@ole.UUCP (Gary Powell)
Newsgroups: comp.lang.c++
Subject: Extensions to []
Message-ID: <1589@ole.UUCP>
Date: 6 Jun 90 15:30:21 GMT
Reply-To: powell@ole.UUCP (Gary Powell)
Organization: Seattle Silicon Corporation, Bellevue, WA.
Lines: 46

I am new to C++ but after a seminar and some play time I tried writting
a class for two diminsional arrays.  What I found myself wanting was
a overloaded operator [][](int)(int).  However my GNU g++ 1.35 compiler
complains bitterly when I tried to code this.  Why not use the (int,int)
operator? Well I was using that for the initialization. It would seem to
me that since C allows array[][] access that C++ should allow overloading
of this also.

With this background has there been any discussion on the overloading of
[][] ....[]?

And is this a reasonable extension to the language?

Resons for doing this are that N'dim. arrays are a pain to pass
to functions.  With a class I can add the extra information for bounds
checking and pass the arguement as a single pointer and let the compiler
call my code to access the array.

class TWO_DIM {
public:
    TWO_DIM(int r,int c) { /* initialize  */}
    int & operator[][](int r)(int c) { /* bound check */ return & array [r][c];}
    ~TWO_DIM() {delete array;}
private:
    int *array,
	max_col,
	max_row;
};

subroutine (TWO_DIM &i-arry)
{
    i-arry[5][2] = i-arry[2][5];   // garbage code.
}
main()
{
    TWO_DIM i-array(10,20);

    i-array[0][15] = 5;

    subroutine (i-array);
}
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