Subj : Re: Returning structures from template classes
To   : borland.public.cpp.borlandcpp
From : DJV
Date : Sun Oct 02 2005 10:17 am


Thanks for reminding me that a class is, fundamentally, a structure itself.  I added a "success" unsigned integer variable, then modified the contructor code and the code to set one matrix equal to another to include it.  I can now send an indication of success or failure with the matrix that is being returned.

maeder@glue.ch (Thomas Maeder [TeamB]) wrote:
>"DJV" <ventruella@hotmail.com> writes:
>
>[Too much prose and not enough C++ for may taste; I have great
>difficulties understanding your problem. At least please illustrate
>your prose with code or pseudo-code.]
>
>> I am trying to return both a matrix and a simple unsigned integer
>> from a matrix class in a header file to indicate whether a matrix
>> has been successfully inverted.  It occurred to me to use a pointer
>> to a structure, but two problems developed.
>
>Why returning two things at the same time?
>
>Is it because to determine whether a matrix is invertible requires you
>to basically try to invert it? If this is the reason, consider
>creating an inverter class. E.g.:
>
>int main()
>{
>  typedef matrix<double,3> matrix_type;
>  matrix_type m(/* some initialization */);
>  matrix_type::inverter i(matrix);
>  if (i.success())
>    ; // use i.result()
>  else
>    ; // do something else
>}
>
>
>> 1.  In the "main()" body of the calling routine that calls the
>> matrix class function, I do not seem to be able to create a matrix
>> object as part of a structure.  I can create a matrix object (or
>> several of them if I wish) in the same "main()" body, but only by
>> themselves,not as part of a structure.  I can not assign the matrix
>> size in the structure.  I can declare a Matrix<complex> q, but not a
>> Matrix<complex> q(3,3), as I can outside of the structure.
>
>Please show us what you are attempting to do and what the compiler has
>to say about it.

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