reset an array in a structure

[mark smit]

Hello!

I would like to know if I'm at fault here or PBDLLv6 doesn't support this feature.

type MYTYPE
wigits(32) as long
end type

dim temp as MYTYPE

reset temp.wigits() 'This line give me a sytax error

Cheers!

[Colin Schmidt]

Hello,

This works and will do the same thing. It shouldn’t take to much longer than having PB do it. If you needed something faster you could use pointers and overwrite a string of NULL’s to the location of the array.

I have no idea why you can’t simple say: RESET temp.wigits()

TYPE MYTYPE
    wigits(32) AS LONG
END TYPE
FUNCTION PBMAIN
    LOCAL temp AS MYTYPE
    REGISTER count AS LONG
    FOR count = 0 TO 32
        RESET temp.wigits(count)
    NEXT count
END FUNCTION

Colin Schmidt

------------------
Colin Schmidt & James Duffy, Praxis Enterprises, Canada

[Lance Edmonds]

An array within a UDT is not the same as a conventional array, so you cannot manipulate them in the same way.

An array in a UDT should be thought of as a 'table' - essentially it just defines a block of memory within a UDT to simplify access to smaller sections of that UDT member.

If you are regularly clearing a UDT array in your code, then you may be better off defining a UNION for that section - of which the UNION contains the array and a fixed-length string of the same length. That way it is a simple task of setting the string data to erase the numeric array.

UNION iArrayType
  Wigits(32) AS LONG
  sWigits AS STRING * 128
END UNION
 
TYPE MyTypeType
  a AS LONG
  b AS iArrayType
  c AS LONG
END TYPE
 
DIM MyType as MyTypeType
' Now clear the array:
MyType.b.sWigits = STRING$(0, 128)

It's amazing how often a UNION can make life easier - they are often overlooked by programmers and offer all sorts of ways to "recast" data in different ways!


------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Colin Schmidt]

The Union is a much better idea… Like you said, I completely overlooked them. I’ll definitely add them to my arsenal They’ll be very usefull in databases.

Thanks,
Colin Schmidt

------------------
Colin Schmidt & James Duffy, Praxis Enterprises, Canada

[mark smit]

Thank you for your answers, they both seem to work very well!

Cheers!

------------------

[Charles Dietz]

Colin,

I could not get your code with RESET to work. In fact, contrary to the PB/DLL
users' manual (p. 313), I couldn't get RESET to work on a user-defined type
at all. I had to use temp.wigits(count) = 0 for your code to work.

I also implemented Lance's code, but found that his STRING$ parameters were
reversed. The implementation should be as follows:

   #COMPILE EXE
   UNION iArrayType
      Wigits(32) AS LONG
      sWigits AS STRING * 128
   END UNION

   TYPE MyType
      a AS LONG
      b AS iArrayType
      c AS LONG
   END TYPE

   FUNCTION PBMAIN
      LOCAL temp AS MYTYPE
      MSGBOX STR$(temp.b.Wigits(5))
      temp.b.wigits(5) = 25
      MSGBOX STR$(temp.b.wigits(5))
      'now reset wigits() array
      temp.b.sWigits = STRING$(128, 0)
      MSGBOX STR$(temp.b.wigits(5))
   END FUNCTION

------------------

[Semen Matusovski]

charles --
1) if to take mark's initial question, best solution is lance' method, posted (p.7) in http://www.powerbasic.com/support/pb...hread.php?t=43
<font face="courier new, courier" size="3"><pre>
#compile exe
type mytype
wigits(32) as long
end type
function pbmain
local temp as mytype
temp.wigits(5) = 25 ' test
lset temp = string$(len(temp),0) ' nothing more !!!
msgbox str$(temp.wigits(5)) ' test
end function
[/CODE]
2) why 128 (instead of 132) ?
wdigits(32) = wdigits (0 : 32)


[this message has been edited by semen matusovski (edited march 18, 2000).]

[Jim Huguley]

Semen.. you have sharp eyes.. 33 x 4 = 132

I prefer this

    #Compile Exe   
    Type MYTYPE      
        wigits(32) As Long   
    End Type   
    Function PbMain      
        Local temp      As MYTYPE
        Local tempEmpty As MYTYPE

        temp.wigits(5) = 25 ' Test
        temp = tempEmpty ' NOTHING MORE !!!
        MsgBox Str$(temp.wigits(5)) ' Test

    End Function

------------------
Jim..
[email protected]

[Charles Dietz]

Well done, Semen.
I appreciate your post... I learned something.

And Jim, I like your code too. And although you're creating two objects,
I don't think it uses any more space than Semen's, since his uses string
space instead.

------------------

[Colin Schmidt]

Charles – your right! I didn’t check the value after the reset, I just assumed that it did what it said it would…

#COMPILE EXE
TYPE MYTYPE
    wigits AS LONG
END TYPE
FUNCTION PBMAIN
    LOCAL temp AS MYTYPE
    LOCAL test AS LONG
    LOCAL mystr AS STRING
    temp.wigits = 1
    test = 1
    mystr = "Hello"
    RESET temp.wigits
    RESET temp
    RESET test
    RESET mystr
    MSGBOX STR$(temp.wigits)
    MSGBOX STR$(test)
    MSGBOX mystr
END FUNCTION

Both the temp and test in this example are not reset…. The mystr does though…

I read all six sentences in the help file on RESET and could not make sense of this. I’m assuming the help file is just wrong and that PB assumes that you will reset any numeric value by using the ever complicated “= 0” statement instead.

Lance, Dave?

Colin Schmidt

------------------
Colin Schmidt & James Duffy, Praxis Enterprises, Canada

[Lance Edmonds]

Has noone read the recent Errata posts in the FAQ forum? There is errata available on the RESET statement as described in the doc's.

BTW, I wrote the code in my earlier message off-the-cuff and did not test it - I guess it's a case of errors and omissions excepted! Sorry folks! Lucky we have people here that can spot even the smallest of errors...!

(I inadvertantly reversed the parameters to STRING$() and dropped the UNION's string member by one) :sigh:


------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Eric Pearson]

Lance --

> Has noone read the recent Errata posts in the FAQ forum?

Semen did... He even posted a link to the appropriate page about RESET in his message (above).

-- Eric

------------------
Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>



[This message has been edited by Eric Pearson (edited March 19, 2000).]