Insert element in string array

[jj2007]

Here is a little proggie that creates and displays a matrix:

Code Select Expand

include \masm32\MasmBasic\MasmBasic.inc
Init
call Matrix
Inkey CrLf$, "ok, press a key"
Exit
Matrix proc
  Dim My$(9, 25)
  For_ Rows=0 To 25 ; A-Z
For_ cols=0 To 9 ; 0-9
mov ecx, Rows
Let My$(cols, Rows)=Str$(cols)+Chr$(ecx+65)
Next
  Next
  For_ n=0 To 9999 ; it stops inserting @ after a while...
Insert My$(3, 3)
Let My$(3, 3)="@@"
Delete My$(5, 5)
  Next
  For_ Rows=0 To 25
For_ cols=0 To 9
Print My$(cols, Rows), " "
Next
Print
  Next
  ret ; don't forget there are little differences to VB ;-)
Matrix endp
end start

Output:
0A 1A 2A 3A 4A 5A 6A 7A 8A 9A
0B 1B 2B 3B 4B 5B 6B 7B 8B 9B
0C 1C 2C 3C 4C 5C 6C 7C 8C 9C
0D 1D 2D @@ @@ @@ @@ @@ @@ @@
@@ @@ @@ @@ @@ @@ @@ @@ @@ @@
@@ @@ @@ @@ @@ 5F 6F 7F 8F 9F
0G 1G 2G 3G 4G 5G 6G 7G 8G 9G
0H 1H 2H 3H 4H 5H 6H 7H 8H 9H
....
0Z 1Z 2Z 3Z 4Z 5Z 6Z 7Z 8Z 9Z
Since I was a bit puzzled by the fact that the middle loop produces only a limited amount of @@ inserts, I converted the proggie to VB to find out what happens there:

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Sub Matrix()
Dim My$(9, 25)
  For Rows = 0 To 25
For cols = 0 To 9
Let My$(cols, Rows) = Str$(cols) + Chr$(Rows + 65)
Debug.Print '"clears" the immediate window; there is a hilarious workaround here: http://www.dailydoseofexcel.com/archives/2004/06/09/clear-the-immediate-window/
Next
  Next
  'Insert how ????
  For Rows = 0 To 25
For cols = 0 To 9
Debug.Print My$(cols, Rows);
Next
Debug.Print
  Next
End Sub

Same output except for the Insert. To my surprise, the help function did not produce anything useful under "Insert". A Google search reveals that the VB community works with hilarious workarounds involving RtlZeroMem etc - wow...

My old GfaBasic knows Insert and Delete but only for one-dimensional arrays.
I must have a legit copy of PB somewhere but can't find it - probably on an old Win98 puter. Can somebody be so kind to either test the proggie in PB or at least copy the documentation of Insert/Delete?

Thanks, Jochen

[clive]

The output makes sense. The @@ never go beyond element (5, 5) because you delete whatever gets there, and the array pulls back

After 1 iteration you'd get this, shifting every thing from (3, 3) 3D, and loosing 4F which had arrived at (5, 5)

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0A 1A 2A 3A 4A 5A 6A 7A 8A 9A
0B 1B 2B 3B 4B 5B 6B 7B 8B 9B
0C 1C 2C 3C 4C 5C 6C 7C 8C 9C
0D 1D 2D @@ 3D 4D 5D 6D 7D 8D
9D 0E 1E 2E 3E 4E 5E 6E 7E 8E
9E 0F 1F 2F 3F 5F 6F 7F 8F 9F
0G 1G 2G 3G 4G 5G 6G 7G 8G 9G
0H 1H 2H 3H 4H 5H 6H 7H 8H 9H
....
0Z 1Z 2Z 3Z 4Z 5Z 6Z 7Z 8Z 9Z

[jj2007]

Thanks, Clive. It seems indeed plausible. In the meantime, I found the PB equivalent here:

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ARRAY INSERT statement
Purpose: Insert a single item into a given array.
Syntax: ARRAY INSERT array([index]) [FOR count] [, expression]
ARRAY INSERT inserts a single data item into array, an n-dimensional array
...
ARRAY INSERT throws away the data in last element of array

I wonder why they discard the last element - it costs absolutely nothing, in terms of speed & size, to resize the pointer table...
But at least PB does have an Insert, in contrast to VB, and it even handles n-dimensional arrays.