Announcement

**Peter P Stephensen** · 11 Dec 2000, 03:26 AM

It seemes to work...but I am not sure I understand how the allocation
takes place. I tried to make a GPF with the following code.

Regards
Peter

Later: Now I understand...very nice!
(I made a minor change to InitDS)

Code:

#compile exe
 
type DS
    v as dword      '// VarPtr for maintenance
    s as string ptr '// StrPtr to actual data
end type
  
sub InitDS( ds as DS)
    ds.s = varptr(ds)
end sub	
  
sub PutDS(ds as DS, byval txt as string)
    [email protected] = txt
end sub
  
function GetDS(ds as DS) as string
    function = [email protected]
end function
  
function pbmain
   
    local s as DS : InitDS s
   
    PutDS s, "This is a test"
  
    msgbox GetDS(s)	
  
    PutDS s, repeat$(5000,"A")
  
    msgbox GetDS(s)	
  
end function

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

[This message has been edited by Peter P Stephensen (edited December 11, 2000).]

**Semen Matusovski** · 11 Dec 2000, 03:55 AM

Edwin --
This way looks easier for me

Code:

   #Compile Exe
   Global DummyString As String

   Type MyStruct
      MyString As String Ptr
      OtherData As Long
   End Type

   Function PbMain
      Dim SP As MyStruct
      SP.MyString = StrPtr (DummyString) ' Initial (it's necessary)
      
      [email protected] = "This is a test"
      MsgBox [email protected]
   End Function

------------------
E-MAIL: [email protected]

**jcfuller** · 11 Dec 2000, 04:26 AM

Edwin,
I think you will find that the strptr moves???
This is the way I do it.

James

Code:

#COMPILE EXE
#DIM ALL
#REGISTER  NONE
#INCLUDE "WIN32API.INC"
#INCLUDE "OLEAUT32.INC"
TYPE MYTYPE
  Str1		AS ASCIIZ PTR
  dwData	AS DWORD
  Str2		AS ASCIIZ PTR
END TYPE

GLOBAL SP() As MYTYPE
 
 
Function PbMain
  REDIM SP( 1 To 2 )
  SP(1).Str1 = SysAllocStringByteLen("This is a Test",50)
  MsgBox SP(1)[email protected]
  SysReAllocString VARPTR(SP(1).Str1),(Time$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & CHR$(0))      
  MsgBox SP( 1 )[email protected]
  SysFreeString SP(1).Str1
End Function

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

**Lance Edmonds** · 11 Dec 2000, 04:33 AM

Cute concept - it is similar to how VB handles dynamic strings in UDT's.

A few other comments:

1. The UDT contains a dynamic string pointer, so it should be assigned with VARPTR(dynamic string) instead of STRPTR(dynamic string)

2. Since the string has no initial content in the (incorrect) above example, assigning text to the target is very likely to cause a GPF since the wrong target address was used to begin with.

3. If the global string is changed with a normal assignment, the pointer is guaranteed to be void, which means updating the pointer in the UDT whenever the string data is changed with a standard concatenation/assignment. To prove it, try this slight variation of the (incorrect) code and you'll see it fails miserably at the second MSGBOX (since STRPTR was used instead of VARPTR).

Code:

   #COMPILE EXE
   GLOBAL DummyString AS STRING

   TYPE MyStruct
      MyString AS STRING PTR
      OtherData AS LONG
   END TYPE

   FUNCTION PBMAIN
      DIM SP AS MyStruct
      SP.MyString = STRPTR(DummyString) ' Initial (it's necessary)

      [email protected] = "This is a test"
      MSGBOX [email protected]

      DummyString = REPEAT$(20, "<*>")
      MSGBOX [email protected] ' hmmm! We risk a GPF at this point...

      MSGBOX DummyString
   END FUNCTION

The moral is that you have to plan the use of this type of code VERY carefully to ensure you are working with valid memory addresses, and that you start off using the correct target address (VARPTR)

My $0.02...

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

**Semen Matusovski** · 11 Dec 2000, 05:08 AM

Lance --
Well, I'm agree about initial value .
What do you think about this ?

Code:

   #Compile Exe
   Global DummyString As String
   
   Type MyStruct
      MyString As String Ptr
      OtherData As Long
   End Type

   Function PbMain
      Dim SP As MyStruct
      SP.MyString = VarPtr(DummyString) ' Initial
      MsgBox Hex$(StrPtr([email protected])), , "Initial location of the string data"

      [email protected] = "This is a test"
      MsgBox [email protected]
      
      MsgBox Hex$(StrPtr([email protected])), , "New location"
      
   End Function

------------------
E-MAIL: [email protected]

**Edwin Knoppert** · 11 Dec 2000, 09:21 AM

Before we get to much alternatives..

Is there a method without using alloc api's?

JC, the method you describe is not a string, i need chr$(0) too.

Semen, we just tried a lot of data, after reading 3 entries a GPF occures.

------------------
[email protected]com

**Peter P Stephensen** · 11 Dec 2000, 10:35 AM

Just an idea. Did not have the time to test it...
Make a DynString-object, defined by the header-file:

Code:

#if not %def(%DS_INC)
%DS_INC = 1
'------------------------------------------------------
  
%NewDS  = 1    ' Constructor
%KillDS = 2    ' Destructor
%GetDS  = 3    ' Methods
%PutDS  = 4
 
function DSMainFunction(byval funcID as long, str as string, byval param as long) as long
 
    static DSMeromy() as string
    static count as long
    static HandleStack() as long
    static InitFlag as long
  
    local hDS as long
 
    if InitFlag = 0 then
        InitFlag = 1
        redim DSMemory(0)
        redim HandleStack(0)
    end if
  
    select case funcID
    case %NewDS     ' Constructor
        if ubound(HandleStack()) > 0 then
            hDS = HandleStack(ubound(HandleStack()))
            redim preserve HandleStack(ubound(HandleStack())-1)				
        else
            incr count : hDS = count
            redim preserve DSMemory(count) 
        end if
 
        DSMemory(hDS) = str
        function = hDS : exit function
 
        case %KillDS     ' Destructor
            redim preserve HandleStack(ubound(HandleStack())+1)				
            HandleStack(ubound(HandleStack())) = param
 
        ' Methods:
        case %GetDS
            function = strptr(DSMemory(param)) : exit function
 
        case %PutDS
            DSMemory(param) = str			
 
        end select
 
        function = 0
 
end function

 
' Wrapper functions
function NewDS(byval txt as string) as long
    function = DSMainFunction(%NewDS, txt,0)
end function
 
sub KillDS(byval hDS as long) as long
    DSMainFunction %KillDS, "",hDS
end sub
 
function GetDS(byval hDS as long) as string
 
    local pz as asciiz pointer
  
    pz = DSMainFunction(%GetDS, txt,hDS)
 
    function = @pz
 
end function
 
sub SetDS(byval hDS as long, byval txt as string)
    DSMainFunction %PutDS, txt, hDS
end sub
 
#endif ' %DYNSTR_INC
'------------------------------------------------------

It should be used this way:

Code:

#compile exe
#include "ds.inc"
 
type MyStruct
    hString as long
    OtherData as long
end type
 
function pbmain
  
    dim SP as MyStruct
  	
    SP.hString = NewDS("This is a test")
  
    msgbox GetDS(SP.hString)
   
    PutDS SP.hString, repeat$(1000,"A")
   
    msgbox GetDS(SP.hString)
  
end function

Regards
Peter

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

**Semen Matusovski** · 11 Dec 2000, 11:13 AM

GPF ?! I don't see GPF here (under ME).
1000 times looks enough for me.

Code:

   #Compile Exe
   
   Type MyStruct
      MyString As String Ptr
      OtherData As Long
   End Type
   
   Function PbMain
      Dim nStruct As Long
      nStruct = 100
      
      Dim i As Long, j As Long
      ReDim SP(1 To nStruct) As MyStruct, DummyString(1 To nStruct) As String
      For i = 1 To nStruct: SP(i).MyString = VarPtr(DummyString(i)): Next ' Initial
          
      ' Test
      For j = 1 To 1000
         For i = 1 To nStruct
            SP(i)[email protected] = "Element #" + Str$(i) + " Cross #" + Str$(j)
        Next
      Next
      
      MsgBox SP(1)[email protected], , SP(nStruct)[email protected]
      
   End Function

------------------
E-MAIL: [email protected]

**Edwin Knoppert** · 11 Dec 2000, 11:38 AM

I had no time to test these suggestions.
At the moment i maintain 2 arrays, 1 for dyn. strings only.
This was the safest.

I also created 2000000 entries, and read them again.
Worked fine until..

I kept it all in a global array.
While reading it from a different procedure the 3th entry crashed!

So, try different procedures.
I noted that the varptr stored was different and equal to the strptr!!

If we can overcome this we have a nice dyn. allocation WITHOUT using heapalloc etc..

BTW, note that i need strings (with CHR$(0))

??

------------------
[email protected]

**Semen Matusovski** · 11 Dec 2000, 12:17 PM

Well, 2 mln entries, 5 crosses, different procedures.
No problems on my PÑ (except time).

Probably, your problems are memory/OS relative.
Sure, that really is used much more memory than string data requires
(additional information about allocated blocks; alignment; fragmentation).

Code:

   #Compile Exe

   Type MyStruct
      MyString As String Ptr
      OtherData As Long
   End Type

   %nStruct = 2000000
   %nCross = 5

   Global SP() As MyStruct, DummyString() As String

   Sub Fill
      Dim i As Long, j As Long
      ReDim SP(1 To %nStruct), DummyString(1 To %nStruct)
      For i = 1 To %nStruct: SP(i).MyString = VarPtr(DummyString(i)): Next ' Initial

      For j = 1 To %nCross
         For i = 1 To %nStruct
            SP(i)[email protected] = "Element #" + Str$(i) + " Cross #" + Str$(j)
        Next
      Next
   End Sub

   Sub Test
      Dim i As Long, j As Long
      j = %nCross
      For i = 1 To %nStruct
         If SP(i)[email protected] <> "Element #" + Str$(i) + " Cross #" + Str$(j) Then MsgBox "Oh"
      Next
      MsgBox "Ok"
    End Sub

   Function PbMain
      Fill
      Test
  End Function

------------------
E-MAIL: [email protected]

**Paul Squires** · 11 Dec 2000, 02:29 PM

Hi,

(RE: Peter P. Stephensen's Code snippet)

I fixed up Peter's example so now it will run okay.
Does anyone out there foresee any problems with using his
approach? I like the idea that it is self-contained in an
Include file.

#COMPILE EXE
#INCLUDE "ds.inc"

TYPE MyStruct
hString AS LONG
OtherData AS LONG
END TYPE

FUNCTION PBMAIN

DIM SP AS MyStruct

SP.hString = NewDS("This is a test")
MSGBOX GetDS(SP.hString)

SetDS SP.hString, REPEAT$(1000,"A")
MSGBOX GetDS(SP.hString)

END FUNCTION

#IF NOT %DEF(%DS_INC)
%DS_INC = 1
'------------------------------------------------------

%NewDS = 1 ' Constructor
%KillDS = 2 ' Destructor
%GetDS = 3 ' Methods
%PutDS = 4

FUNCTION DSMainFunction(BYVAL funcID AS LONG, str AS STRING, BYVAL param AS LONG) AS LONG

STATIC DSMemory() AS STRING
STATIC count AS LONG
STATIC HandleStack() AS LONG
STATIC InitFlag AS LONG

LOCAL hDS AS LONG

IF InitFlag = 0 THEN
InitFlag = 1
REDIM DSMemory(0)
REDIM HandleStack(0)
END IF

SELECT CASE funcID
CASE %NewDS ' Constructor
IF UBOUND(HandleStack()) > 0 THEN
hDS = HandleStack(UBOUND(HandleStack()))
REDIM PRESERVE HandleStack(UBOUND(HandleStack())-1)
ELSE
INCR count
hDS = count
REDIM PRESERVE DSMemory(count)
END IF

DSMemory(hDS) = str
FUNCTION = hDS
EXIT FUNCTION

CASE %KillDS ' Destructor
REDIM PRESERVE HandleStack(UBOUND(HandleStack())+1)
HandleStack(UBOUND(HandleStack())) = param

' Methods:
CASE %GetDS
FUNCTION = STRPTR(DSMemory(param))
EXIT FUNCTION

CASE %PutDS
DSMemory(param) = str

END SELECT

FUNCTION = 0

END FUNCTION

' Wrapper functions
FUNCTION NewDS(BYVAL txt AS STRING) AS LONG
FUNCTION = DSMainFunction(%NewDS, txt, 0)
END FUNCTION

SUB KillDS(BYVAL hDS AS LONG)
DSMainFunction %KillDS, "", hDS
END SUB

FUNCTION GetDS(BYVAL hDS AS LONG) AS STRING

LOCAL pz AS ASCIIZ pointer
LOCAL txt AS STRING

pz = DSMainFunction(%GetDS, txt, hDS)

FUNCTION = @pz

END FUNCTION

SUB SetDS(BYVAL hDS AS LONG, BYVAL txt AS STRING)
DSMainFunction %PutDS, txt, hDS
END SUB

#ENDIF ' %DYNSTR_INC
'------------------------------------------------------

------------------
Paul Squires
[email protected]

**jcfuller** · 12 Dec 2000, 04:04 AM

Edwin,
You say you need chr$(0)? Actually the SysAllocStrByteLen is provided for just that
purpose. I just showed access using string related functions. See if this might
be a bit closer.
James

Code:

#COMPILE EXE
#DIM ALL
#REGISTER  NONE
#INCLUDE "WIN32API.INC"
#INCLUDE "OLEAUT32.INC"
TYPE MYTYPE
  Str1		AS ASCIIZ PTR
  dwData	AS DWORD
  Str2		AS ASCIIZ PTR
END TYPE

GLOBAL SP() As MYTYPE
 
 
Function PbMain
  LOCAL dwTempPtr	AS DWORD PTR, _
        sTemp		AS STRING
  REDIM SP( 1 To 2 )
  sTemp = "This is a Test"+CHR$(0,13,10)+"Some more text"
  SP(1).Str1 = SysAllocStringByteLen((sTemp),LEN(sTemp))
  'Ok you need chr$(0)'s in your string. Just get the length and use peek$
  'the length is the dword pointer preceeding the actual ASCZII PTR
  dwTempPtr = SP(1).Str1
  DECR dwTempPtr
  sTemp = PEEK$(SP(1).Str1,@dwTempPtr)
  MsgBox FORMAT$(LEN(sTemp))
  SysReAllocString VARPTR(SP(1).Str1),(Time$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & ", " & Date$ & CHR$(0))      
  MsgBox SP( 1 )[email protected]
  SysFreeString SP(1).Str1
End Function

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

[This message has been edited by jcfuller (edited December 12, 2000).]

**Edwin Knoppert** · 12 Dec 2000, 06:47 AM

Yes, i think so, a year ago i saw the complete buffer from an asciiz.
It's simply an offset in the string containing the 0.

But unf. now i need to destroy the alloc. data myself.
The point is that i can use simple strings (Maybe with as simple wrapper)
The procedure i wrote did that until i reread the data in a diff. proc.
I didn't the last examples because i'm to busy.
At the moment we use 2 arrays wich solves the problem.
The Strptr as described above was much faster.

If there's a way to 'fool' or help PB to make this a sure working procedure

------------------
[email protected]

Announcement

Dynamic strings in struct..

Dynamic strings in struct..

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment