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From: rmartin@clear.com (Bob Martin)
Newsgroups: comp.lang.c++
Subject: Re: Array of class objects
Keywords: array, initialization, class objects
Message-ID: <1990Nov15.050358.16043@clear.com>
Date: 15 Nov 90 05:03:58 GMT
References: <1756@enuxha.eas.asu.edu>
Organization: Clear Communications, Inc.
Lines: 52

In article <1756@enuxha.eas.asu.edu> hocker@enuxha.eas.asu.edu (Charles C. Hocker) writes:
>
>Hello,
>
>	I am having touble trying to created an array of objects of 
>class pnt using TC++.  My code is as follows:
>
>class pnt {
>	public:
>		int X, Y, Z;
>		pnt (int x = 0, int y = 0, int z = 0) {X=x; Y=y; Z=z;}
>};
>
>class	pnts {
>	public:
>		int Count;
>		pnt Pnts [MAX_PNTS];  // pnt from above
>		pnts (int count = 0) {Count = count;}
>};
>
>int	main (void)
>{
>	pnts	Points;
>// ...
>
>}
>
>I recieve an error to the effect "cannot find pnt::pnt()" when 
>I compile my program.  

I'll take a stab at answering this.  My manual (which happens to be
the version of the ARM published by SUN) says in 12.1 that:

	"A default constructor for a class X is a constructor of the
	form X::X().  A default constructor will not be generated for
	a class X if any constructor has been declared for class X.

Now, since you declared pnt::pnt(x,y,z).  The compiler did _NOT_
generate the default constructor pnt::pnt().  Yet it needs to use
the pnt::pnt() constructor when constructing the array in the pnts
class.  Note that the array cannot be constructed with pnt(x,y,z)
since the compiler has no way of knowing what values should be
assigned to x, y or z.

So the solution is for you to declare and implement a pnt::pnt()
constructor.  Perhaps it should set the coordinates to zero...

-- 
+-Robert C. Martin-----+:RRR:::CCC:M:::::M:| Nobody is responsible for |
| rmartin@clear.com    |:R::R:C::::M:M:M:M:| my words but me.  I want  |
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