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allow empty arrays
Posted: Sun Dec 04, 2016 4:34 pm
by #NULL
why not allow to specify -1 or nothing for Dim and ReDim to define an empty array?
a modified example of ExtractXMLArray() shows me that pb can handle empty arrays already:
Code: Select all
Xml$ = "<array></array>"
;Xml$ = "<array><element>1</element><element>10</element><element>100</element></array>"
If ParseXML(0, Xml$) And XMLStatus(0) = #PB_XML_Success
Dim MyArray(0) ; will be resized by the next call
ExtractXMLArray(MainXMLNode(0), MyArray())
Debug "ArraySize : " + ArraySize(MyArray())
For i = 0 To ArraySize(MyArray())
Debug MyArray(i)
Next i
Else
Debug XMLError(0)
EndIf
currently for an 'add' routine i did something like the following, including the fixing of the array size when you are done with adding values.
Code: Select all
Procedure addColor(Array colors(1), color)
colors(ArraySize(colors())) = color
ReDim colors(ArraySize(colors()) + 1)
EndProcedure
Dim colors1(0)
addColor(colors1(), $ffff3333)
addColor(colors1(), $ffff5555)
addColor(colors1(), $ffff6666)
ReDim colors1(ArraySize(colors1()) - 1)
now at least i know i can create empty arrays via xml parsing.
Re: allow empty arrays
Posted: Sun Dec 04, 2016 5:28 pm
by #NULL
here is an xml version of clearArray() for one dimensional integer arrays
Code: Select all
Procedure clearArray(Array arr(1))
Protected xml
xml = ParseXML(#PB_Any, "<array></array>")
If xml
If XMLStatus(xml) = #PB_XML_Success
ExtractXMLArray(MainXMLNode(xml), arr())
Else
Debug "XMLError: " + XMLError(xml)
EndIf
FreeXML(xml)
Else
Debug "ParseXML() failed."
EndIf
EndProcedure
Procedure addValue(Array arr(1), value)
ReDim arr(ArraySize(arr()) + 1)
arr(ArraySize(arr())) = value
EndProcedure
Dim values(0)
clearArray(values())
addValue(values(), 123)
addValue(values(), 456)
Debug "ArraySize : " + ArraySize(values())
For i=0 To ArraySize(values())
Debug values(i)
Next
Re: allow empty arrays
Posted: Sun Dec 04, 2016 11:08 pm
by IdeasVacuum
what difference does it make though?
Re: allow empty arrays
Posted: Mon Dec 05, 2016 8:00 am
by nco2k
to not waste resources and cpu time.
seriously though, sometimes you have to call a function first, to find out the required number of elements. once you know that number, you can redim your array and fill it with data. dim allocates and zeroes the memory and redim preserves the existing data. its kind of a total waste in this case.
pseudocode:
Code: Select all
Protected Dim MyArray.MyStructure(-1), Count
ApiStuff_(0, @Count)
ReDim MyArray(Count - 1)
ApiStuff_(@MyArray(), @Count)
For i = 0 To Count - 1
Debug MyArray(i)\Whatever
Next
c ya,
nco2k
Re: allow empty arrays
Posted: Mon Dec 05, 2016 8:14 am
by Mistrel
It still bothers me that arrays allocate with n+1 the initial size. I always forget this since it's always n in every other language I use.