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From: crowl@rochester.arpa (Lawrence Crowl)
Newsgroups: comp.lang.c++
Subject: Re: complex arrays
Message-ID: <1053@sol.ARPA>
Date: Tue, 4-Aug-87 11:57:05 EDT
Article-I.D.: sol.1053
Posted: Tue Aug  4 11:57:05 1987
Date-Received: Thu, 6-Aug-87 01:43:47 EDT
References: <3400003@uicsgva>
Reply-To: crowl@rochester.UUCP (Lawrence Crowl)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 37

In article <3400003@uicsgva> rahmeh@uicsgva.UUCP writes:
>The following program:
>
>    #include <complex.h>
>    main()
>    {
>        complex a[2];
>    }
>
>causes the C++ compiler to produce the following error message:
>
>line 5: sorry, not implemented: default arguments for constructor for vector
>of class complex
>
>If you have an explanation please let me know.

The C++ compiler implements initialization of class instance elements within
an array by passing the address of the class constructor to another routine
which loops though the elements.  Since the looping routine has no knowledge
of the constructor, it requires that the constructor take no parameters.  The
definition of the class complex in complex.h shows one constructor taking two
parameters.  True, the parameters are defaulted, but the constructor still
takes two parameters.  This the source of the error.  This can be fixed by
changing part of the class definition from:

    complex(double r = 0.0, double i = 0.0) { re=r; im=i; }

to:

    complex() { re=0.0; im=0.0; }
    complex(double r, double i = 0.0) { re=r; im=i; }

Keepers of the compiler (or library), can you make this update?
-- 
  Lawrence Crowl		716-275-8479	University of Rochester
		     crowl@cs.rochester.arpa	Computer Science Department
 ...!{allegra,decvax,seismo}!rochester!crowl	Rochester, New York,  14627