Desperately Need help with arrays

[Guest]

Hi, I've been working at something with arrays for some time now and am just stuck. I have looked on this forum a lot and am afraid I just can't get my head around the syntax involved in getting an array to work properly. I want an array to be written from variables created through some math in a loop in multi-dimensional format. I managed it once, then edited it to try and give the two results on a horizontal axis rather than everything on the vertical, ie (0,0) was above (0,1) then shut the computer off, without checking that by trying to change the layout I messed something else up and now everything is screwed!!
I originally wrote the code to just print to a file, and it looked really good, but I think that to make the file more usable later on, pulling the values and reusing them for a second program, an array would be a better choice than a regular file. Or would it? I don't know...
To make a long story short (too late) could anyone give a heads up for a complete idiot's guide to array syntax for powerbasic?? All the sites I have found gloss over arrays very quickly and each of the commands for arrays even more quickly.
Thanks for reading.

[Gösta H. Lovgren-2]

Hi, I've been working at something with arrays for some time now and am just stuck. I have looked on this forum a lot and am afraid I just can't get my head around the syntax involved in getting an array to work properly. I want an array to be written from variables created through some math in a loop in multi-dimensional format. I managed it once, then edited it to try and give the two results on a horizontal axis rather than everything on the vertical, ie (0,0) was above (0,1) then shut the computer off, without checking that by trying to change the layout I messed something else up and now everything is screwed!!
I originally wrote the code to just print to a file, and it looked really good, but I think that to make the file more usable later on, pulling the values and reusing them for a second program, an array would be a better choice than a regular file. Or would it? I don't know...
To make a long story short (too late) could anyone give a heads up for a complete idiot's guide to array syntax for powerbasic?? All the sites I have found gloss over arrays very quickly and each of the commands for arrays even more quickly.
Thanks for reading.

What specifically do you want to know? Kind of hard to give a general answer to something as vague as this request. Even bet to oost some code you would like clarified.

===============================================
"I kissed my first girl
and smoked my first cigarette on the same day.
I haven't had time for tobacco since."

Arturo Toscanini
===============================================

[Rodney Hicks]

I originally wrote the code to just print to a file, and it looked really good, but I think that to make the file more usable later on, pulling the values and reusing them for a second program, an array would be a better choice than a regular file.

Arrays and Files are two separate and distinct features and are not interchangeable. Arrays can be stored in a File, thus Files can contain arrays. Arrays are a type of holder of data in memory and Files are a storage of data, usually on disc.
The following code shows the development of an array, putting data into each array element, and, via the MSGBOX, displaying each element to help you with this part of your puzzle.

#COMPILE EXE
#DIM ALL

FUNCTION PBMAIN () AS LONG
  LOCAL myarray() AS LONG
  LOCAL x, y, counter,calculation AS LONG
  DIM myarray(0 TO 2, 0 TO 3)
  FOR x = 0 TO 2
    FOR y = 0 TO 3
      INCR counter
      calculation=2*counter
      myarray(x,y)=calculation
      MSGBOX "Element #"+FORMAT$(counter)+" myarray(x,y) where x="+FORMAT$(x) _
      +" y="+FORMAT$(y)+" equals "+FORMAT$(calculation)
    NEXT y
  NEXT x
  MSGBOX "Element # 1  myarray(0,0)="+FORMAT$(myarray(0,0))+$CRLF+ _
         "Element # 2  myarray(0,1)="+FORMAT$(myarray(0,1))+$CRLF+ _
         "Element # 3  myarray(0,2)="+FORMAT$(myarray(0,2))+$CRLF+ _
         "Element # 4  myarray(0,3)="+FORMAT$(myarray(0,3))+$CRLF+ _
         "Element # 5  myarray(1,0)="+FORMAT$(myarray(1,0))+$CRLF+ _
         "Element # 6  myarray(1,1)="+FORMAT$(myarray(1,1))+$CRLF+ _
         "Element # 7  myarray(1,2)="+FORMAT$(myarray(1,2))+$CRLF+ _
         "Element # 8  myarray(1,3)="+FORMAT$(myarray(1,3))+$CRLF+ _
         "Element # 9  myarray(2,0)="+FORMAT$(myarray(2,0))+$CRLF+ _
         "Element # 10 myarray(2,1)="+FORMAT$(myarray(2,1))+$CRLF+ _
         "Element # 11 myarray(2,2)="+FORMAT$(myarray(2,2))+$CRLF+ _
         "Element # 12 myarray(2,3)="+FORMAT$(myarray(2,3))
   MSGBOX FORMAT$(myarray(0,0))+"  "+FORMAT$(myarray(1,0))+"  "+FORMAT$(myarray(2,0))+$CRLF+ _
         FORMAT$(myarray(0,1))+"  "+FORMAT$(myarray(1,1))+"  "+FORMAT$(myarray(2,1))+$CRLF+ _
         FORMAT$(myarray(0,2))+"  "+FORMAT$(myarray(1,2))+"  "+FORMAT$(myarray(2,2))+$CRLF+ _
         FORMAT$(myarray(0,3))+"  "+FORMAT$(myarray(1,3))+"  "+FORMAT$(myarray(2,3))                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
END FUNCTION

[Guest]

This is my loop with the array printing in the middle of it. As it stands, there is only one dimension to the array. I'd ultimately like it to have three but will settle for two.
the array has previously been dimmed
DO WHILE h < x
ARRAY ASSIGN a()=e
PRINT #1, A()

IF e = 1 THEN
GOTO 3
END IF

e = e + d
e = e - x

h = h + 1

LOOP

x and d are constants previously declared. What I'd like to have is the array storing the values in three columns, x, h and e (ideally, the x values would only show up in the first row and then be blank thereafter; the h is the count). I can do this with the regular print function into a file but then I'd need an arary to get the values back to work. I'm not actually sure if what I'm asking makes sense or is doable, but I think it is.

[Michael Mattias]

>What I'd like to have is the array storing the values in three columns,

I assume this means you may have "many" rows, each row with three columns?

There are three ways to do this off the top of my head...

1. Use a two-dimensional array, with one dimension being row number, the other dimension being column number. You'll want to put the column as the first subscript (this is counter-intuitive, I know, but it's what you'll need to do to resize the array) It will also require that all three columns are of the same data type (STRING, LONG, etc) or can be formatted to the same type.

   REDIM   MyARray (2, nRow-1)   'columns 0, 1,2; as many rows as needed

2. Use a single dimension array of UDTs

TYPE MyRow 
  Col1         AS    whatever 
  Col2         AS    whatever
  Col3         AS    whatever
END TYPE
....
     REDIM Row(nRow-1) AS MyRow

3. Use three separate arrays

    REDIM   COL1 (nRow-1) AS whatever
    REDIM   COL2 (nRow-1) AS whatever
    REDIM   COL3 (nRow-1) AS whatever

All three methods allow for fairly straightforward storage to and retrieval from a disk file.

(I personally like option two here).

BTW, when you post code, please use Code Tags. THis page can be had by clicking the "BB code" link at the lower left of the page.

Also, this line of code...

ARRAY ASSIGN a()=e

...is probably not what you want. That will only assign the first element of the array (subscript 0 if one dimension, subscript 0,0 if two-dimension, etc). So if you do it in a loop all you are doing is changing that one element each time thru.

MCM

[Dave Biggs]

Comments on your posted example..

ARRAY ASSIGN a()=e < Wrong use of ARRAY ASSIGN
Should be like "ARRAY ASSIGN x&() = 1,2,3,4,5,.." i.e. one time assignment of
successive array elements. Not successive assignments of individual elements.

Also the use of Print #1, a() inside the loop could be an error?
That form of Print# writes the whole array to the file at once. You'd probably
want to wait until the array was built before writting it to the file.
Something like this..

  
#Debug Display On     ' Useful when developing apps with arrays (traps out of bounds errr etc.)
#Dim All
#Register None
#Include "WIN32API.INC"
'------------------/
 
Function PBMain()
 Dim sTest$, h&, e&, d&, x&, Rec&, n&
 Dim a&()
 Dim FileData$()
 
  x = 6 : d = 8
  Redim a(0 To x-1)
 
  Do While h < x
    e = e + d
    e = e - x
    a(h) = e
      sTest = sTest + Str$(a(h)) + $Cr
    h = h + 1                  
  Loop
 
  Close #1
    MsgBox sTest,,"Results" : sTest = ""
 
  Open "Test.txt" For Output As #1
  Print #1, a()       ' NB numeric values saved as ASCII text equivalent values
  Close #1            ' delimited w/ $CRLF
 
  Open "Test.txt" For Input As #1
  FileScan #1, Records To Rec
  ReDim FileData(1 To Rec)
  Line Input #1, FileData()
  Close #1
 
  ReDim a(1 To Rec)
  For n = 1 To Rec
                      ' Convert file data back to numeric array
    a(n) = Val(FileData(n))
    sTest = sTest + Str$(a(n)) + $Cr
  Next
    MsgBox sTest,,"From file"
 
End Function
'------------------/PBMain

[Rodney Hicks]

This works on your array construction and pretty much leaves the file arrangements alone since Dave did a good job with that. In some ways this is more like a puzzle than a request for help!

#COMPILE EXE
#DIM ALL
'CONSTANTS
%d=10          '%d and %x are now the "constants previously declared" and the values never change
%x=6
FUNCTION PBMAIN () AS LONG
  LOCAL a() AS LONG
  LOCAL e,h,fnum AS LONG
  DIM a(0 TO %x-1)
  DO WHILE h < %x
    a(h)=e     'assign the value of e to the first element of the array a(0) because at this point h=0
    'left out the PRINT # statement, will use it once the array is full
    'left out the IF block because at this point e=0 and where line 3 is I have no idea
    'if it was meant to go to the PRINT # statement and succeeded you'd have created an endless loop.
    e=e+%d
    e=e-%x
    INCR h    'the same as h=h+1
  LOOP
  fnum=FREEFILE    'the use of FREEFILE means you don't need the first CLOSE statement in Dave's example
  'OPEN statement        '
  'PRINT # fnum, a()
  'CLOSE # fnum
  MSGBOX "1st a(0)="+FORMAT$(a(0))+$CRLF+"2nd a(1)="+FORMAT$(a(1))+$CRLF+"3rd a(2)="+FORMAT$(a(2))+$CRLF+ _
         "4th a(3)="+FORMAT$(a(3))+$CRLF+"5th a(4)="+FORMAT$(a(4))+$CRLF+"6th a(5)="+FORMAT$(a(5))
'the array:      this would be your 'h' column
'           a(0)=0
'           a(1)=4
'           a(2)=8
'           a(3)=12
'           a(4)=16
'           a(5)=20
'to get the %x and %d columns you need an array with 2 dimensions and you would make the following
'changes to the above code.
'Change DIM a(0 TO %x-1) to DIM a(0 TO 2,0 TO %x-1)
'Change a(h)=e to a(0,h)=e
'Insert between e=e+%d and e=e-%x the following a(1,h)=e
'Insert after the line e=e-%x the following a(2,h)=e
'Comment out the two lines of the MSGBOX or change to reflect the 2 dimensions
'You can copy and paste them into position.

'just those changes should give you an array like:
'           the 'h' column  the %d column  the %x column

'           a(0,0)=0        a(1,0)=10      a(2,0)=4
'           a(0,1)=4        a(1,1)=14      a(2,1)=8
'           a(0,2)=8        a(1,2)=18      a(2,2)=12
'           a(0,3)=12       a(1,3)=22      a(2,3)=16
'           a(0,4)=16       a(1,4)=26      a(2,4)=20
'           a(0,5)=20       a(1,5)=30      a(2,5)=24

'This is the closest I can figure from your description
'You might try inserting your own values for %d and %x

'  *********************************************COPIED so I didn't have to keep switching to and fro
'DO WHILE h < x
'ARRAY ASSIGN a()=e
'PRINT #1, A()
'
'IF e = 1 THEN
'GOTO 3
'END IF
'
'e = e + d
'e = e - x
'
'h = h + 1
'
'LOOP
'x and d are constants previously declared. What I'd like to have is the array storing the values
'in three columns, x, h and e (ideally,the x values would only show up in the first row and then
'be blank thereafter; the h is the count). I can do this with the regular print function into a
'file but then I'd need an arary to get the values back to work. I'm not actually sure if what I'm
'asking makes sense or is doable, but I think it is.
END FUNCTION

A couple of things as yet unclear about your prob..puzzle!
If 'h is the count' then the first assignment should be a(h)=h but then you would not be storing the calculated value of e in a single dimension array, you'd merely be storing the count. If you make the suggested changes to make it a two dimensional array, I suggest making the change to a(0,h)=h instead of a(0,h)=e, thus your 2d array will store the count in the 'h' column.
"ideally, the x values would only show up in the first row and then be blank thereafter" does not make any sense to me unless that was what that IF block was supposed to do.

[Dave Biggs]

I've modified my previous sample to demo two dimensions as per Rod's post..

#Debug Display On     ' Useful when developing apps with arrays (traps out of bounds errr etc.)
#Dim All
#Register None
#Include "WIN32API.INC"
'------------------/
 
Function PBMain()
 Dim sTest$, h&, e&, d&, x&, Rec&, n&
 Dim a&()
 Dim FileData$()
 
    x = 6 : d = 8
  Redim a(0 To 2, 0 To x-1)   ' 3 'columns' by 6 'rows'
 
  Do While h < x              ' h = 'row' number
    e = e + d
    e = e - x
    a(0,h) = h                ' assign a value to each column in this row
    a(1,h) = e                '
    a(2,h) = x                '
      sTest = sTest + Str$(a(0,h)) + $Tab + Str$(a(1,h)) + $Tab + Str$(a(2 ,h)) + $Cr
    h = h + 1                 ' INCR h 
  Loop
 
    MsgBox  " h" + $Tab + " e" + $Tab + " x" + $CR + $CR + _
            sTest,,"Results" : sTest = ""
 
  Open "Test.txt" For Output As #1
  Print #1, a()       ' NB numeric values saved as ASCII text equivalent values
  Close #1            '    delimited w/ $CRLF (new line per data value)
 
  ' some time later :) ...
 
  Open "Test.txt" For Input As #1
  FileScan #1, Records To Rec
  ReDim FileData(0 To 2, 1 To Rec/3)
  Line Input #1, FileData()
  Close #1
 
  ReDim a(0 To 2, 1 To Rec/3)
  For n = 1 To Rec/3
                      ' Convert (ASCII) file data back to numeric array
    a(0,n) = Val(FileData(0,n)) : a(1,n) = Val(FileData(1,n)) : a(2,n) = Val(FileData(2,n))
    sTest = sTest + Str$(a(0,n)) + $Tab + Str$(a(1,n)) + $Tab + Str$(a(2,n)) + $Cr 
  Next
    MsgBox " h" + $Tab + " e" + $Tab + " x" + $CR + $CR + _
           sTest,,"From file"
 
End Function
'------------------/PBMain
 ' File Test.txt data values stored thus:
 ' column 0, row 0
 ' column 1, row 0
 ' column 2, row 0
 ' column 0, row 1
 ' column 1, row 1
 ' column 2, row 1
 ' column 0, row 2
 ' etc...

[Rodney Hicks]

Very nicely done Dave!!!
The only change to what you've done that I would make is to change the comment
' 3 'columns' by 1 'row'
to
' 3 'columns' by 6 'rows'

Strangely enough, this program, and the description of what someone wanted to program are very similar to how I got started in programming many years ago, before even Turbo Basic. I had asked my little brother( a computer sciences student ) to show me how to do some input and calculations and display, no filing routines though(I hadn't thought that far ahead or didn't even know the concept).
After muttering something about "gutter basic"(The first model Atari) he proceeded to write 30 lines of code and left. He also, a couple of years later, told me not to waste my time with the BASICA I believe it was that came with my first IBM clone but to get "TURBO BASIC"(and later the name change to POWERBasic).
It seems it has taken more than twenty years to close the circle.

[Dave Biggs]

Thank you Rod

I fixed the comment, I guess I was thinking, first is the Column dimension then there's the Row dimension... I wonder, what would you call a third dimension? Axis maybe ??

It's been an interesting exercise that was overdue for me and did help put a few things in place (The cell is easily boggled by array stuff!)

[Gösta H. Lovgren-2]

I took Dave's great example and modified it a tad using a 1 based array instead of 0 based. It may be easier to follow for a newby to PB (and even some old dogs who are slow on the pickup - chez moi for example) Note number alignment in second msgbox as well.

#Debug Display On     ' Useful when developing apps with arrays (traps out of bounds errr etc.)
#Dim All
#Register None
#Include "WIN32API.INC"
'------------------/
 
Function PBMain()
 Dim sTest$, h&, e&, d&, x&, Rec&, n&
 Dim a&()
 Dim FileData$()
1: 
    x = 6 : d = 8
  ReDim a(1 To 3, 1 To x)   ' 3 'columns' by 6 'rows'
2: 
   h = 1
  Do While h <= x              ' h = 'row' number
    e = e + d
    e = e - x
    a(1,h) = h                ' assign a value to each column in this row
    a(2,h) = e                '
    a(3,h) = x                '
      sTest = sTest + Str$(a(1,h)) + $Tab + Str$(a(2,h)) + $Tab + Str$(a(3 ,h)) + $Cr
    h = h + 1                 ' INCR h 
  Loop
3: 
    MsgBox  " h" + $Tab + " e" + $Tab + " x" + $Cr + $Cr + _
            sTest,,"Results" : sTest = ""
 
  Open "Test.txt" For Output As #1
  Print #1, a()       ' NB numeric values saved as ASCII text equivalent values
  Close #1            '    delimited w/ $CRLF (new line per data value)
 
  ' some time later :) ...
 
  Open "Test.txt" For Input As #1
  FileScan #1, Records To Rec
  ReDim FileData(1 To 3, 1 To Rec/3)
  Line Input #1, FileData()
  Close #1
 
  ReDim a(1 To 3, 1 To Rec/3)
  For n = 1 To Rec/3
                      ' Convert (ASCII) file data back to numeric array
    a(1,n) = Val(FileData(1,n)) : a(2,n) = Val(FileData(2,n)) : a(3,n) = Val(FileData(3,n))
    sTest = sTest + Using$("###",a(1,n)) + $Tab + Using$("###",a(2,n)) + $Tab + Using$("###",a(3,n)) + $Cr 
  Next
    MsgBox " h" + $Tab + " e" + $Tab + " x" + $Cr + $Cr + _
           sTest,,"From file"
 
End Function
'------------------/PBMain
 ' File Test.txt data values stored thus:
 ' column 0, row 0
 ' column 1, row 0
 ' column 2, row 0
 ' column 0, row 1
 ' column 1, row 1
 ' column 2, row 1
 ' column 0, row 2
 ' etc...__________________

(Note the line numbers. Got a couple gpf's while doing it and line numbers pinpointed it in no time {grin})

===============================
"I don't even butter my bread;
I consider that cooking."
Katherine Cebrian
===============================

[Rodney Hicks]

Dave
I would think that if we were only to deal with three dimensions we would use x-axis, y-axis, and z-axis. Since we are using table terms to describe the dimensions (column, row) I would think 'sheet' might be the third term employed, as you might in a spreadsheet. Not a very intuitive term though!(Possibly because we're programmers, not users.)

Gösta
You do not need the colons if you use line numbers, only with labels, nor do line numbers need to be on a separate line by themselves. Try it, you'll find that each line of code can have its own line number. Why we would reintroduce them though is a bit beyond me, unless to explain something to someone. I have no idea what the debugger thinks of them though.

None of us has figured out what the following lines were for in the original puzzle and it would be nice to hear from the perp.. poster of this puzzle.

IF e = 1 THEN
GOTO 3
END IF

Obviously data dependent and we don't know the values of his constants. Perhaps as a means to iterate the loop so the x value didn't get stored?

[Dave Biggs]

Sheet ! - I should have thought of that

[Gösta H. Lovgren-2]

Gösta
You do not need the colons if you use line numbers, only with labels, nor do line numbers need to be on a separate line by themselves. Try it, you'll find that each line of code can have its own line number. Why we would reintroduce them though is a bit beyond me, unless to explain something to someone. I have no idea what the debugger thinks of them though.

I introduced the line numbers in to quickly/efficiently/fastly/speedily/accurately/unaggravatinlgly narrow down where the gpf was getting tripped using a heretofore generally unknown/unused function of the new De Bug Display On feature of PBWin9 - See -
http://www.powerbasic.com/support/pb...ad.php?t=40802

Dunno what the Debugger thinks of them but I know I like them. {grin}

I left them in the example code to show just how easily once formidably difficult to find errors can get tracked down in PB9. (JIC the sagging AUD rises once again.)

===================================================
"If you were plowing a field,
which would you rather use?
Two strong oxen or 1024 chickens?"
Seymour Cray (1925-1996), father of supercomputing
===================================================

[Michael Mattias]

Open "Test.txt" For Output As #1
  Print #1, a()       ' NB numeric values saved as ASCII text equivalent values
  Close #1            '    delimited w/ $CRLF (new line per data value)

You might want to consider using the JOIN$ function here, along with PARSE when loading from disk. That could preserve the "rows" nature of the data.

[Guest]

I appreciate all of your input very much, and I'm sure that the code you gave gives you something on your computers. The thing is, on mine it gives a blank (I tried both Rodney and Dave's code inserted as the main part of the loop and no message boxes appeared). Nothing is printed from the array, so I assume nothing was stored in the array, but again I do not know. I'm going to try another language because I need to learn, properly learn, arrays from the beginning before I have a hope in hell of achieving what I want. I know what they are and what they are for, but I don't really know how to create them yet or how my creation, when at long last I have one, looks.
By the way, the

IF e = 1 THEN
GOTO 3
END IF

that is to end the program earlier, when it happens that h < x happens after e=1

Thanks again for your help, but truthfully all I did was cut and paste your ideas without great understanding. I need great understanding first.
Michael.

[Dave Biggs]

Sorry we couldn't help yet. Maybe if you post a small compilable sample you are using to learn by we could help you debug it?
BTW what compiler are you using?

[Rodney Hicks]

If you are using PBCC then the program will compile but not give any output. We assumed since you were posting in the PBWin(There is a PBCC forum as well) forum that you were using the PBWin version.
If you wait a bit, either I or someone else will develop a program that works in PBCC. In fact, the existing program likely needs very little change to work in PBCC. I haven't time at the moment, but possibly by morning I will have.
Could you give us the values of d and x?

[Guest]

it is the windows version...

[Michael Mattias]

>Nothing is printed from the array so I assume nothing was stored in the array,

None of the code you have posted contains any output statements at all, so we can't tell if your problem is getting the data into your array or if that data are loading correctly but there is an error in your 'displaying' code.

That "small compilable example demonstrating the problem" would go a long way to solving your challenge.