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Passing Arrays

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Richard Russell
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Re: Passing Arrays
« Reply #17 on: Mar 16^th, 2014, 11:08am »

on Mar 13^th, 2014, 9:20pm, JosephE wrote:

Code:

' Simple Array Functions
' by Joseph Essin

If you are working with arrays, you will be interested to know that LBB supports some whole-array arithmetic operations, for example adding two arrays together without needing to code a loop:

Code:

    a() = b() + c()

Previously this facility has been undocumented (frankly I had forgotten that it was supported!) but now I've written a Wiki article listing the various things you can do:

http://bb4w.wikispaces.com/Array+arithmetic

Richard.

« Last Edit: Aug 21^st, 2015, 9:26pm by Richard Russell »

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JosephE
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Re: Passing Arrays
« Reply #18 on: Mar 16^th, 2014, 10:41pm »

on Mar 16^th, 2014, 11:08am, Richard Russell wrote:

If you are working with arrays, you will be interested to know that LBB supports some whole-array arithmetic operations, for example adding two arrays together without needing to code a loop

Wow, that's amazing. And very handy.

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Richard Russell
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Re: Passing Arrays
« Reply #19 on: Mar 22^nd, 2014, 10:52pm »

on Mar 13^th, 2014, 9:20pm, JosephE wrote:

I'm trying to make a few functions to do a redim preserve

The code below now works; it requires LBB v2.53, and the BYREF is essential to allow the array to be redimensioned inside the function/sub:

Code:

' Simple Array Functions
' by Joseph Essin
' Feel free to use in your own code. No need to credit me.
'
' For use with LBB:
' http://www.bbcbasic.co.uk/lbb/
'
' The functionality to make this work is not found in
' Liberty BASIC alone. This is for use with Richard Russell's
' Liberty BASIC Booster "compiler."
'
' Please find LBB below:
'
' http://www.bbcbasic.co.uk/lbb/
' -------------------------------------------------------------- '

' These are necessary for the Array Library.
' Don't name any of your arrays these names
' or you'll be subject to data loss.
Redim ArrayLib(0)
' -------------------------------------------------------------- '


Redim things(5) ' Make it hold five things

For i = 1 To 5
	things(i) = 5^i
	Print i, things(i)
Next i

Print "UBound before redim preserve: "; UBound(things())

Call RedimPreserve things(), 10

Print "UBound after redim preserve: "; UBound(things())

End


Function UBound(array())
    ' Returns the upper index limit of array().
    ' ---------------------------------------------------------- '
    ' Special thanks to Richard for the implementation of the
    ' binary chop method.
    ' ---------------------------------------------------------- '
    s = 2^24
    do
        On Error Goto [Error]
        [Error]
        s = int(s / 2)
        temp = array(UBound + s)
        UBound = UBound + s
    loop until s = 0
End Function



Sub RedimPreserve byref array(), newSize
	' Redimensions the given one-dimensional array() to the
	' specified newSize.
    ' ---------------------------------------------------------- '
	' Array indexes begin at 0, so keep that in mind when
	' specifying newSize.
	' ---------------------------------------------------------- '
	u = UBound(array()) ' Get the upper limit
	Redim ArrayLib(u)
	For i = 0 To u
        ArrayLib(i) = array(i) ' Get old contents
	Next i
	Redim array(newSize) ' Resize given array.
	For i = 0 To u
        array(i) = ArrayLib(i) ' Replace old contents that were lost.
	Next i
End Sub

Richard.

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JosephE
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Re: Passing Arrays
« Reply #20 on: Mar 23^rd, 2014, 11:33pm »

on Mar 22^nd, 2014, 10:52pm, Richard Russell wrote:

The code below now works; it requires LBB v2.53, and the BYREF is essential to allow the array to be redimensioned inside the function/sub:

Wow, you've been busy! Thank you

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bluatigro
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Re: Passing Arrays
« Reply #21 on: Feb 17^th, 2015, 09:56am »

pasing arrays into subs and functions
ok thats nice

but how do i make a function that outputs a array ?

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Richard Russell
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Re: Passing Arrays
« Reply #22 on: Feb 17^th, 2015, 11:47am »

on Feb 17^th, 2015, 09:56am, bluatigro wrote:

but how do i make a function that outputs a array ?

You pass the array BYREF, as follows:

Code:

    call mySub myArray()
    print myArray(50)
    end

sub mySub byref a()
    dim a(100)
    a(50) = 12345
end sub

Here myArray() does not yet exist when the sub is called; the local array a() is created inside the sub and then passed back to the caller as myArray(). On return from the sub a() ceases to exist.

LB 4 doesn't have any functionality like this; arrays are always global so it is impossible to write a general-purpose function which operates on any specified array. This is in my opinion a major weakness.

Richard.

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JosephE
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Re: Passing Arrays
« Reply #23 on: Mar 1^st, 2015, 03:07am »

Just wanted to follow up and say thanks for your help. The ability to re-dimension arrays and preserve their contents is very useful.

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JosephE
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Re: Passing Arrays
« Reply #24 on: Mar 1^st, 2015, 03:36am »

In fact, here's an up-to-date version of the code that supports scaling of string and numeric arrays:

Code:

' Simple Array Functions
' by Joseph Essin and Richard Russell
'
' For use with LBB:
' http://www.bbcbasic.co.uk/lbb/
'
' The functionality to make this work is not found in
' Liberty BASIC alone. This is for use with Richard Russell's
' Liberty BASIC Booster "compiler." Richard even customized LBB
' to allow these user-defined functions to work.
'
' Please find LBB below:
' http://www.bbcbasic.co.uk/lbb/
' -------------------------------------------------------------- '

' -------------------------------------------------------------- '
' These are necessary for the Array Library.
' Don't name any of your arrays these names
' or you'll be subject to data loss.
redim ArrayLib(0)
redim ArrayLib$(0)
' -------------------------------------------------------------- '
function nsize(array())
  ' Returns the upper index limit of the numeric array array().
  s = 2^24
  do
    on error goto [Error]
    [Error]
    s = int(s / 2)
    temp = array(nsize + s)
    nsize = nsize + s
  loop until s = 0
end function

function size(array$())
  ' Returns the upper index limit of the string array array$().
  s = 2^24
  do
    on error goto [Error]
    [Error]
    s = int(s / 2)
    temp$ = array$(size + s)
    size = size + s
  loop until s = 0
end function

sub preserve byref array(), newSize
	' Redimensions the given one-dimensional numeric array to the
	' specified newSize.
	u = nsize(array()) ' Get the upper limit
	redim ArrayLib(u)
	for i = 0 To u
    ArrayLib(i) = array(i) ' Get old contents
	next i
	redim array(newSize) ' Resize given array.
	for i = 0 To u
    array(i) = ArrayLib(i) ' Replace old contents
	next i
end sub

sub preserve$ byref array$(), newSize
	' Redimensions the given one-dimensional string array to the
	' specified newSize.
	u = size(array$()) ' Get the upper limit
	redim ArrayLib$(u)
	for i = 0 To u
    ArrayLib$(i) = array$(i) ' Get old contents
	next i
	redim array$(newSize) ' Resize given array.
	for i = 0 To u
    array$(i) = ArrayLib$(i) ' Replace old contents
	next i
end sub

« Last Edit: Mar 1^st, 2015, 03:38am by JosephE »

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