Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!ut-emx!boerner
From: boerner@ut-emx.uucp (Brendan B. Boerner)
Newsgroups: comp.lang.pascal
Subject: Re: (R)Re: Quick Directories/Better Sorts
Message-ID: <40124@ut-emx.uucp>
Date: 24 Nov 90 22:06:10 GMT
References: <25082@adm.brl.mil>
Organization: UT Austin Computation Center, Microcomputer Technologies
Lines: 36

In article <25082@adm.brl.mil> CDCKAB%EMUVM1.BITNET@cunyvm.cuny.edu ( Karl Brendel) writes:
[...]
>Unfortunately, if
>
>        Array[1..5000]of index
>
>gives "structure too large" (leading to the original message in this
>thread), then
>
>        ^Array[1..5000]of index
>
>will also give "structure too large". 5000*SizeOf(Index) = 85000 bytes.
>
>You subsequently proposed a solution which _will_ work: the array of
>pointers (or pointer to an array of pointers).
[...]

I disagree with Karl on the first point:  the SizeOf a variable of
type ^array[1..5000] of index will be 4 (it's a pointer).  Using
New(IndexPtrVar) will result in 85000 bytes being allocated on the
heap.

The array of pointers will result in 5000 * SizeOf(Ptr) = 20000
bytes on the stack with some variable amount on the heap.  The
pointer to an array of pointers will result in SizeOf(Ptr) = 4
bytes on the stack with 20000 + some variable amount bytes on the
heap.  The last two are really only different (other than how to
dereference them) in that one places the array of pointers on the
stack, the other on the heap.

Brendan
-- 
Brendan B. Boerner		Phone: 512/471-3241
Microcomputer Technologies	The University of Texas @ Austin
Internet: boerner@emx.cc.utexas.edu     UUCP: ...!cs.utexas.edu!ut-emx!boerner
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