PureBasic Forums - English

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Structure player
  name.s
  NewList gangs.GANG()  <-- This would be my second linked list
EndStructure

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structure StreetType
  name.s
  nr.w
  *parent
  *child
endstructure

structure DataBaseType
  name.s
  etc.l
  *street
endstructure

newlist streets.StreetType()
newlist database.DataBaseType()

; ok now add an entry
addelement(database())
addelement(streets())
database()\name = "Vain"
database()\street = @streets()
*ptr.StreetType = @streets()
street()\name = "somewhere"
; he lives on another address too so..
addelement(street())
street()\name = "somewhere else"
*ptr\child = @street()

; now you can access this structure like this
resetlist(database())
while nextelement(database())
  *ptr = database()\*street
  if *ptr ; we have a street
    debug *ptr\name
    while *ptr\child
      *ptr = *ptr\child
      debug *ptr\name
    wend
  endif
wend

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structure GANG
    Id.b
EndStructure

Structure GANGLIST
    lw_Node.ListNode
    *gang.GANG
EndStructure

Structure PLAYER
    *mylist.ListHeader
    *gangs.GANGLIST
EndStructure

Dim player.PLAYER(3)
exterminators.GANG


dll_NewList(@player(0)\mylist, SizeOf(PLAYER) - SizeOf(ListNode))
player(0)\gangs = dll_AddElement(@player(0)\mylist)
player(0)\gangs\gang = @exterminators

dll_NewList(@player(1)\mylist, SizeOf(PLAYER) - SizeOf(ListNode))
player(1)\gangs = dll_AddElement(@player(1)\mylist)
player(1)\gangs\gang = @exterminators

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xincludefile "double_linked_lists.pb"


; Simple structure for storing data about all characters
; or people (as an example)
Structure Character
    c_Node.ListNode     ; This must be the first item, and should be a regular variable, not a pointer

    ; Now you put all the data you want to store in the structure
    ; Only name for now since this is simple
    c_Name.s        ; Character name
EndStructure


; Simple structure for storing a list of gangs
Structure Gang
    g_Node.ListNode     ; Again, this must be first since each gang will be stored in a list

    ; Now your data comes here
    g_Name.s                ; Gang name
    g_Hood.s                ; Area of control

    g_Members.ListHeader    ; List for the members of the gang. Thie list must not be a pointer
EndStructure


DefType.ListHeader  gang_list   ; The main list for storing gangs
DefType.Gang        *gang       ; Pointer to a gang item, for working with list
DefType.Character   *char       ; Pointer to a character item, for working with lists


If OpenConsole()

    PrintN(Str(dll_NewList(@gang_list, SizeOf(Gang) - SizeOf(ListNode))))

    Repeat
        Print("Enter gang name or leave blank to quit: ")
        gang_name.s = Input()
        PrintN("")

        If gang_name""
            ; Gang name entered, create new item
            *gang = dll_AddElement(@gang_list)

            ; make sure we only try to use it if successful
            If *gang
                *gang\g_Name = gang_name
                
                Print("Enter area of control: ")
                *gang\g_Hood = Input()
                PrintN("")

                ; Create the list for members - you must use the full
                ; name to the lh_Head field due to a bug in PB you cannot
                ; simply use the g_Member item.
                dll_NewList(@*gang\g_Members\lh_Head, SizeOf(Character) - SizeOf(ListNode))

                ; Now we add the gang members, in a similar way to
                ; when we create the gangs
                Repeat
                    Print("  Enter member name or leave blank to stop: ")
                    member_name.s = Input()
                    PrintN("")

                    If member_name""
                        *char = dll_AddElement(@*gang\g_Members\lh_Head)
                        If *char
                            *char\c_Name = member_name
                        EndIf
                    EndIf
                Until member_name=""
            EndIf
        EndIf
        
    Until gang_name=""


    ; Now we display the contents of the lists to show you it worked
    *gang = gang_list\lh_Head
    While *gang
        PrintN("The gang '"+*gang\g_Name+"' controls "+*gang\g_Hood+". Members are:")

        *char = *gang\g_Members\lh_Head
        While *char
            Debug *char
            PrintN("foo")
            PrintN("  "+*char\c_Name)
            
            *char = *char\c_Node\ln_Succ
        Wend

        PrintN("End of members")
        
        ; Move onto next item
        *gang = *gang\g_Node\ln_Succ
    Wend


    PrintN("Freeing memory")
    
    ; Call this to free up memory in each list
    ; First we go to the first item in the gangs
    *gang = gang_list\lh_Head

    ; And go round this loop until the pointer is null (end of gang list)
    While *gang

        ; Clear the list for members of the gang
        ; Must use the @ symbol to get the address of the start
        ; of the list header inside the gang item structure
        dll_DeleteList(@*gang\g_Members\lh_Head)

        ; Move onto next item
        *gang = *gang\g_Node\ln_Succ
    Wend


    ; Finally we must clear the main list
    dll_DeleteList(@gang_list)

    PrintN("Press return to exit")
    Input()
    CloseConsole()
EndIf

End