Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!snorkelwacker!mit-eddie!mit-amt!peter
From: peter@mit-amt.MEDIA.MIT.EDU (Peter Schroeder)
Newsgroups: comp.lang.c++
Subject: Re: Constant Question
Message-ID: <1466@mit-amt.MEDIA.MIT.EDU>
Date: 23 Jan 90 16:20:31 GMT
References: <130286@sun.Eng.Sun.COM>
Organization: MIT Media Lab, Cambridge, MA
Lines: 58

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Reply-To: peter@media-lab.media.mit.edu (Peter Schroeder)
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Organization: MIT Media Lab, Cambridge MA
Keywords: const

Ok, I'll bite my tongue off...

In article <1103@etnibsd.UUCP> vsh@etnibsd.UUCP (Steve Harris) writes:
>In article <1405@mit-amt.MEDIA.MIT.EDU>
peter@media-lab.media.mit.edu (Peter Schroeder) writes:
>>In article <130286@sun.Eng.Sun.COM> rbogen%dreams@Sun.COM
(Richard Bogen) writes:
    main()
    {
     const float PI = 3.14159;
     float *const ptr = &PI;
     *ptr = 0.0;
     printf("%PI = %f\n",PI);
    }
    
[some smart comments of mine]

   main()
   {
    const float PI = 3.14159;
    const float *ptr = &PI;
    *ptr = 0.0; // error
    printf("%PI = %f\n",PI);
   }

>Peter corrected the code, but didn't answer the question!

Well, umh, ...

So, I just ran this through cfront 2.0 with

	float *const ptr = &PI;

I do not get a complaint and it prints 0.0. Now that is a bug as far as
I am concerned.

If I write

	float *ptr = &PI;

the compiler complains (rightly so).

>My g++ generates a warning at line 2, and creates a second object for ptr
>to point to, so PI remains unchanged and *ptr is initalized to 3.14159 but
>then is changed to 0.0.

I am not sure I would like that, at least not without a warning about using
an intermediate.

Peter
peter@media-lab.media.mit.edu