Undim does not clear the strings

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Math89

21

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Joined: 23rd Jan 2004

Location: UK

Posted: 27th Jul 2007 19:26 Edited at: 27th Jul 2007 19:32

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I've found this rather annoying bug, when you delete an array (defined as string), the array is deleted, but not the strings.
Just take a look at the task manager (ctrl+alt+del) and you'll see the memory growing. If you don't set any string, the memory doesn't change.

+ Code Snippet

Sync On
Sync Rate 0

count = 15

Do
	Cls
	Print "Please check the task manager"

	Dim array(count) As String
	For v = 1 to count
		array(v) = str$(rnd(100000))
	Next v
	UnDIm array(0)

	Sync
Loop

EDIT : It's possible to avoid this bug using the undocumented "free string()" command, but I think, it should be automatically done

.

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IanM

Retired Moderator

22

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Joined: 11th Sep 2002

Location: In my moon base

Posted: 28th Jul 2007 02:59

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It's the same with EMPTY ARRAY too.

This code shows that memory is returned when freed (ie, the VM size decreases back to approx where is was).

+ Code Snippet

sync off
sync sleep 1

wait key

a = make memory(1024*1024*200) ` 200mb

wait key

delete memory a

wait key
end

This code shows approx the same amount of memory being allocated in an array, and that it isn't freed:

+ Code Snippet

sync off
sync sleep 1

wait key
dim a(1024*200) as string

for i = 1024 * 200 to 0 step -1
   a(i) = space$(1024)
next

wait key

`for i = 1024 * 200 to 0 step -1
`   a(i) = NullString()
`next

undim a()

wait key
end

function NullString()
   local s as string
endfunction s

Uncomment the for-loop to show what should happen when un-dimming or emptying an array.

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Overdroid

22

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Joined: 22nd Sep 2002

Location:

Posted: 26th Sep 2007 23:32

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What about delete array element?

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Mr Tank

22

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Joined: 25th Nov 2002

Location: United Kingdom

Posted: 12th Mar 2008 14:00 Edited at: 12th Mar 2008 14:01

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Wow, this is pretty annoying. I wonder why this happens.

I had wanted to dim and undim strings loaded from a text file for menus, credits etc., but it appears i need to keep them dimmed permanently. Not a huge hardship i guess.

How are strings stored? They can be any length, right? If instead of undimming i just set all of the values to "", do i actually free up useful memory, or will it be all fragmented, and so probably better just to load the sting info once and leave it loaded?

I guess i could make a program to convert text files into byte files of the ascii codes or something, and a bespoke reader, but that might be slightly anally retentive.

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Bug Reports / Undim does not clear the strings