Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c++
Subject: Re: How to correctly initialize struct/class
Message-ID: <406@taumet.com>
Date: 21 Aug 90 15:44:53 GMT
References: <1990Aug20.220157.24736@sj.ate.slb.com>
Organization: Taumetric Corporation, San Diego
Lines: 74

poffen@sj.ate.slb.com (Russ Poffenberger) writes:

|I want to define a union, such that it can be either a float value, or a
|pointer.
|
|union both {
|  float value;
|  float *value;
|};
|
|Now I want to define a structure (or class) like so that uses several instances
|of this union.
|
|struct data {
|  union both one;
|  union both two;
|  union both three;
|  union both four;
|  union both five;
|};
|
|Now what I need to do is to declare an instance of the struct, but initialize
|all of the fields. Any of the fields may be initialized to either a floating
|point constant, or the address of a floating variable.
|
|e.g.
|
|float f1;
|float f2;
|
|struct data d1 = (&f1,4.3,&f2,7.2,0.0)
|struct data d2 = (0.0,1.0,2.0,3.0,4.0)
|
|etc...
|
|How can I declare a constructor to do this? Is it even possible?

Try this:

class ugly {
    union {
	float f;
	float* p;
    };
public:
    ugly(float  x) { f = x; }
    ugly(float* x) { p = x; }
};

class data {
    ugly u1;
    ugly u2;
    ugly u3;
    ugly u4;
    ugly u5;
public:
    data(ugly a1, ugly a2, ugly a3, ugly a4, ugly a5) {
	u1 = a1;
	u2 = a2;
	u3 = a3;
	u4 = a4;
	u5 = a5;
    }
};

Now you can use
	float f1;
	float f2;

	data d1(&f1, 4.3, &f2, 7.2, 0.0);
	data d2(0.0, 1.0, 2.0, 3.0, 4.0);
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com