Why is this code now broken in v6.12?

[Randy Walker]

Einander gave us a very powerful code sample to insert or delete elements in an array:
https://www.purebasic.fr/english/viewto ... rtL#p36953

But it has a memory error when you try to run his example code. How can this be fixed? And Also, can we make this a feature request? -- insert(array()) , delete(array())

[STARGÅTE]

If you run this old code under x64 processor, all pointers or buffer addresses have to be an integer type.

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Procedure DeleteL(DIR.i,ELEM.L,DM.L) 

Code: Select all

InsertL(VA.L,DIR.i,ELEM.L,DM.L) 

However, also CopyMemory() is miss-used in this code. For CopyMemory() the source and destination buffers may not overlap. But this is the case here. So you have to replace it with MoveMemory().
Besides that, this code wouldn't work for the last element, because the size in CopyMemory or MoveMemory have to be larger than 0.

This Code is not "powerful", it is just historical.

[Randy Walker]

Oh but it is powerful, if you need to insert or delete elelments in an array. Maybe you have better way?

Anyway I checked value of @A() and determined from that I had encountered the classic All .L need to be changed to .i instead, so I did and code ran without any issue.
Thanks!!!

[STARGÅTE]

But this code actually do not delete or insert an element. The array size keeps constant, it just moves the data.
If you insert an element in a full array, this code shifts out the last element.

Here is my version for DeleteArrayElement and InsertArrayElement, written as a macro, to allow multiple atomic data types for the arrays. However, such code (as well as the linked code) are not working with string-arrays or structured arrays.

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Macro DeleteArrayElement(ArrayName, Index)
	If Index >= 0 And Index <= ArraySize(ArrayName())
		If Index < ArraySize(ArrayName())
			MoveMemory(@ArrayName(Index+1), @ArrayName(Index), @ArrayName(ArraySize(ArrayName()))-@ArrayName(Index))
		EndIf
		If ArraySize(ArrayName()) > 0
			ReDim ArrayName(ArraySize(ArrayName())-1)
		Else
			FreeArray(ArrayName())
		EndIf
	EndIf
EndMacro

Macro InsertArrayElement(ArrayName, Index, Value)
	If Index >= 0
		If ArraySize(ArrayName()) = -1
			Dim ArrayName(Bool(Index>=0)*(Index))  ; Bool(Index>=0) is needed here to prevent compiler error for index < 0
		ElseIf Index > ArraySize(ArrayName())
			ReDim ArrayName(Bool(Index>=0)*(Index))  ; Bool(Index>=0) is needed here to prevent compiler error for index < 0
		Else
			ReDim ArrayName(ArraySize(ArrayName())+1)
		EndIf
		If Index < ArraySize(ArrayName())
			MoveMemory(@ArrayName(Index), @ArrayName(Index+1), @ArrayName(ArraySize(ArrayName()))-@ArrayName(Index))
		EndIf
		ArrayName(Index) = Value
	EndIf
EndMacro

Macro ViewArray(ArrayName)
	For I = 0 To ArraySize(ArrayName())
		Debug "[" + I + "] = " + ArrayName(I)
	Next
EndMacro

;- Example

Define Dim MyArray.f(3)

MyArray(0) = 1.0
MyArray(1) = 2.0
MyArray(2) = 3.0
MyArray(3) = 4.0

ViewArray(MyArray)

Debug "Delete:"
DeleteArrayElement(MyArray, 2)
ViewArray(MyArray)

Debug "Insert:"
InsertArrayElement(MyArray, 0, 3.25)
ViewArray(MyArray)

Debug "Insert:"
InsertArrayElement(MyArray, 7, 100)
ViewArray(MyArray)

[Randy Walker]

Ok. I got the original code to work properly. First all the .L variables had to be changed to .i instead and because I am running PB 64 bit the "4"values in both procedures had to be raised to "8". So here is Einander's code again tested and working for PB 64 bit (windows).:

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;By Einander - October 21 - 2003 - PB 3.80
;Procedure DeleteL(@Array(),ELEM,DM) deletes the item indexed by ELEM from Array.i().
; All array items whose indices are >= ELEM are shifted one position up.
; The value of the last element in the array is converted to 0.

Procedure DeleteL(DIR.i,ELEM.i,DM.i) 
  CopyMemory(DIR+(elem+1)*8,DIR+elem*8,(DM-elem)*8)
  PokeL(DIR+DM*8,0)
EndProcedure

; Procedure Insert(VA,@Array,ELEM,DM) inserts VA in Array.i() at position ELEM.
; All items in Array.i  whose indices are >= ELEM are moved one position down.
; The last element in ARRAY.i() is deleted with each Insert.
; Would be nice to icrease the size of the array to fit the last element.

Procedure InsertL(VA.i,DIR.i,ELEM.i,DM.i) 
  CopyMemory(DIR+elem*8,DIR+(elem+1)*8,(DM-elem)*8)
  PokeL(DIR+ELEM*8,VA)
EndProcedure

;::::::::::::::::::::::::::::::::::::::::

DM=10
ELEM=5    ;Element to delete

Dim A.i(DM)
For I=0 To DM : A(I)=I  : Next
Gosub TEST
Debug " "
DeleteL(@A(),ELEM,DM)  ;deletes item 5
Debug "Deleted "+Str(ELEM)
Debug " "
Gosub TEST

InsertL(555,@A(),5,DM)  ; inserts 555 at posic 5
Debug "Inserted 555"
Gosub TEST
MessageRequester("DONE","",0)
End

;     :::::::::::::::::::::::::::::::::::

TEST:
For I=0 To DM
  Debug Str(I)+"  "+Str(A(I))
Next I
Return

Sorry guys. I forgot to mention I was working with 64 bit PB. Master of I/O errors.

[ChrisR]

Here is my version for DeleteArrayElement and InsertArrayElement, written as a macro...

Very pretty and works perfectly
In InsertArrayElement both (Re)Dim ArrayName(Bool(Index>=0)*(Index)) can be simplified to (Re)Dim ArrayName(Index), Index >= 0 is tested before

[miso]

@Randy Walker
If you want to use that version, then PokeL()-s should be replaced with PokeI()-s, *4 for 32 bit, *8 for 64 bit. Still, Stargate's version is perfect, no need to update or fix anything.

[Randy Walker]

Here is my version for DeleteArrayElement and InsertArrayElement, written as a macro

IIII Like it!!! It's beautiful!
THANKS STARGATE

[STARGÅTE]

Here is my version for DeleteArrayElement and InsertArrayElement, written as a macro...

Very pretty and works perfectly
In InsertArrayElement both (Re)Dim ArrayName(Bool(Index>=0)*(Index)) can be simplified to (Re)Dim ArrayName(Index), Index >= 0 is tested before

Unfortunately not^^. Bool(Index>=0) is just a dummy to prevent evaluation during compilation.
Otherwise, for Index = -1, the Macro is evaluated to

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If -1 >= 0
		If ArraySize(ArrayName()) = -1
			Dim ArrayName(-1)

and then the compiler gives an error that Dim ArrayName(-1) have to be positive, even If -1 >= 0 would be false.
I can't use CompilerIf, because then Index must be a constant at all, which I don't want.

[infratec]

And for your 4 to 8 transitions, you should use

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SizeOf(Integer)

Else your code is not working in the x86 version of PB

[ChrisR]

Unfortunately not^^. Bool(Index>=0) is just a dummy to prevent evaluation during compilation.

Thanks for the explanation, not tested with Index = -1, nice workaround then

[Randy Walker]

And for your 4 to 8 transitions, you should use

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SizeOf(Integer)

Else your code is not working in the x86 version of PB

Ok, this i a curious comment. When I try this code (below) I get syntax error on line 2. What did I do wrong?

a.i = 42
Debug SizeOf(a.i)

I tried the original code modified like this (below) but even on a 32 bit machine, it gave results that should happen only on a 64 bit machine. And of course both procedures failed to produce any results.

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;By Einander - October 21 - 2003 - PB 3.80
;Procedure DeleteL(@Array(),ELEM,DM) deletes the item indexed by ELEM from Array.i().
; All array items whose indices are >= ELEM are shifted one position up.
; The value of the last element in the array is converted to 0.
Global bits
a.i = 2147483648  ;<< This is max value for 4 byte integer Plus one!!!
If a.i = 2147483648
  bits = 64
  Debug "64 bit"
Else
  Debug "32 bit"
EndIf

Procedure DeleteL(DIR.i,ELEM.i,DM.i)
  If bits = 64
    CopyMemory(DIR+(elem+1)*8,DIR+elem*8,(DM-elem)*8)
    PokeL(DIR+DM*8,0)
  Else
    CopyMemory(DIR+(elem+1)*4,DIR+elem*4,(DM-elem)*4)
    PokeL(DIR+DM*4,0)
  EndIf
EndProcedure

; Procedure Insert(VA,@Array,ELEM,DM) inserts VA in Array.i() at position ELEM.
; All items in Array.i  whose indices are >= ELEM are moved one position down.
; The last element in ARRAY.i() is deleted with each Insert.
; Would be nice to icrease the size of the array to fit the last element.

Procedure InsertL(VA.i,DIR.i,ELEM.i,DM.i)
  If bits = 64
    CopyMemory(DIR+elem*8,DIR+(elem+1)*8,(DM-elem)*8)
    PokeL(DIR+ELEM*8,VA)
  Else
    CopyMemory(DIR+elem*4,DIR+(elem+1)*4,(DM-elem)*4)
    PokeL(DIR+ELEM*4,VA)
  EndIf
EndProcedure

;::::::::::::::::::::::::::::::::::::::::

DM=10
ELEM=5    ;Element to delete

Dim A.i(DM)
For I=0 To DM : A(I)=I  : Next
Gosub TEST
Debug " "
DeleteL(@A(),ELEM,DM)  ;deletes item 5
Debug "Deleted "+Str(ELEM)
Debug " "
Gosub TEST

InsertL(555,@A(),5,DM)  ; inserts 555 at posic 5
Debug "Inserted 555"
Gosub TEST
MessageRequester("DONE","",0)
End

;     :::::::::::::::::::::::::::::::::::

TEST:
For I=0 To DM
  Debug Str(I)+"  "+Str(A(I))
Next I
Return

 

I still get "64 bit" from the debug line when run on the 32 bit machine, so I'm very lost on this issue. Fortunately STARGATE provideed a working solution.

[idle]

use sizeof(integer)

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;By Einander - October 21 - 2003 - PB 3.80
;Procedure DeleteL(@Array(),ELEM,DM) deletes the item indexed by ELEM from Array.i().
; All array items whose indices are >= ELEM are shifted one position up.
; The value of the last element in the array is converted to 0.

Procedure DeleteI(DIR.i,ELEM.i,DM.i)
 CopyMemory(DIR+(elem+1)*SizeOf(integer),DIR+elem*SizeOf(integer),(DM-elem)*SizeOf(integer))
 PokeI(DIR+DM*SizeOf(integer),0)
EndProcedure

; Procedure Insert(VA,@Array,ELEM,DM) inserts VA in Array.i() at position ELEM.
; All items in Array.i whose indices are >= ELEM are moved one position down.
; The last element in ARRAY.i() is deleted with each Insert.
; Would be nice to icrease the size of the array to fit the last element.

Procedure InsertI(VA.i,DIR.i,ELEM.i,DM.i)

CopyMemory(DIR+elem*SizeOf(integer),DIR+(elem+1)*SizeOf(integer),(DM-elem)*SizeOf(integer))
PokeI(DIR+ELEM*SizeOf(integer),VA)

EndProcedure

;::::::::::::::::::::::::::::::::::::::::

DM=10
ELEM=5 ;Element to delete

Dim A.i(DM)
For I=0 To DM : A(I)=I : Next
Gosub TEST
Debug " "
DeleteI(@A(),ELEM,DM) ;deletes item 5
Debug "Deleted "+Str(ELEM)
Debug " "
Gosub TEST

InsertI(555,@A(),5,DM) ; inserts 555 at posic 5
Debug "Inserted 555"
Gosub TEST
MessageRequester("DONE","",0)
End

; :::::::::::::::::::::::::::::::::::

TEST:
For I=0 To DM
Debug Str(I)+" "+Str(A(I))
Next I
Return

[IceSoft]

See the different sizes:

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Debug SizeOf(Integer)
Debug SizeOf(Long)
Debug SizeOf(Word)
Debug SizeOf(Byte)

And last but Not least:
A PureBasic pointer variable should be ALWAYS a Integer like:

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myPointer.i

[mk-soft]

Better *myPointer