| Re: compile a routine wich inlude a commun [message #47125 is a reply to message #47067] |
Tue, 24 January 2006 08:01   |
peter.albert@gmx.de
Messages: 108
Registered: July 2005
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Senior Member |
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> No, it does not. Whether or not you point to the "complete" variable, or just a part of
> it, a new heap "variable" is created.
>
> IDL> x=indgen(4,4)
> IDL> print, x
> 0 1 2 3
> 4 5 6 7
> 8 9 10 11
> 12 13 14 15
> IDL> p=ptr_new(x)
> IDL> print, *p
> 0 1 2 3
> 4 5 6 7
> 8 9 10 11
> 12 13 14 15
> IDL> print, (*p)[1:2,1:2]
> 5 6
> 9 10
> IDL> (*p)[1:2,1:2] = (*p)[1:2,1:2] + 100
> IDL> print, *p
> 0 1 2 3
> 4 105 106 7
> 8 109 110 11
> 12 13 14 15
> IDL> print, x
> 0 1 2 3
> 4 5 6 7
> 8 9 10 11
> 12 13 14 15
Damn, I should have tried it before. I was so sure :-(
But then, this _is_ a polite group. Nobody murmuring something like
rtfm, while a look in the manual reveals :
"If InitExpr is provided, PTR_NEW uses it to initialize the newly
created heap variable. Note that the new heap variable does not point
at the InitExpr variable in any sense-the new heap variable simply
contains a copy of its value."
Well, here is is, black on white. So you _can't_ alias variables or
subarrays.
Cheers,
Peter
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