Deleting in Linked List

[imbored]

What is it you are trying to achieve?
Having a procedure delete a value from the linked list... also make it a circular linked list.


What is the problem you are having?
I understand the box things
[....|...] [XXXX] [....|...]
..|_______________^

etc... but i dont understand how to program it.

Describe what you have tried to solve this problem
i tried replacing the value that needs to be deleted with the next value and it keeps going untill the end.. but it didnt end up great either i programmed it wrong or its just wrong... i started from scratch from what i had before.

Post any relevant code (You may choose to attach the file instead of posting the code if it is too long)
this is what i got.. it saves the inputs into the linked list and outputs it. it is choppy and inefficient... but i dont really know how to make it more efficient. but first thing is first how to make it delete o.o''

Turing:

var PointerType : collection of     record         Data : string (40)         Next : pointer to PointerType         Prev : pointer to PointerType     end record var Backup : collection of     record         Data : string (40)         Next : pointer to Backup         Prev : pointer to Backup     end record %------------------- procedure--------------------------------------- procedure First (var InsertRecord, ListStart, ListEnd : pointer to PointerType, spNames : string)     new InsertRecord     ListEnd := InsertRecord     ^InsertRecord.Next := nil     ^InsertRecord.Data := spNames     ListStart := InsertRecord end First procedure bFirst (var bIRecord, bListStart, bListEnd : pointer to Backup, spNames : string)     new bIRecord     bListEnd := bIRecord     ^bIRecord.Next := nil     ^bIRecord.Data := spNames     bListStart := bIRecord end bFirst procedure InName (var InsertRecord, ListStart, ListEnd : pointer to PointerType, spName : string, var ipAm : int)     new InsertRecord     ^InsertRecord.Next := ListStart     ^ListStart.Prev := InsertRecord     ^InsertRecord.Data := spName     ListStart := InsertRecord     ipAm += 1 end InName procedure bInName (var bIRecord, bListStart, bListEnd : pointer to Backup, spName : string)     new bIRecord     ^bIRecord.Next := bListStart     ^bListStart.Prev := bIRecord     ^bIRecord.Data := spName     bListStart := bIRecord end bInName procedure Circular (var InsertRecord, ListStart, ListEnd : pointer to PointerType)     InsertRecord := ListEnd end Circular procedure OutName (ListEnd : pointer to PointerType, ipAm : int)     var i : int := 0     var TempList := ListEnd     loop         i += 1         put ^TempList.Data         exit when i = ipAm         TempList := ^TempList.Prev     end loop end OutName procedure bOutName (bListEnd : pointer to Backup, ipAm : int)     var i : int := 0     var TempList := bListEnd     loop         i += 1         put ^TempList.Data         exit when i = ipAm         TempList := ^TempList.Prev     end loop end bOutName %----------------------- main---------------------------------------- var InsertRecord, ListStart, ListEnd : pointer to PointerType var bIRecord, bListStart, bListEnd : pointer to Backup var sNames : string var iAm : int := 1 var iAm2 : int := 1 put "Input the name of a contestant" get sNames : * First (InsertRecord, ListStart, ListEnd, sNames) bFirst (bIRecord, bListStart, bListEnd, sNames) if (sNames = 'Fin') or (sNames = 'fin') then     %nothing else     loop         put "Input the name of a contestant"         get sNames : *         exit when (sNames = 'fin') or (sNames = 'Fin')         InName (InsertRecord, ListStart, ListEnd, sNames, iAm)         bInName (bIRecord, bListStart, bListEnd, sNames)     end loop end if Circular (InsertRecord, ListStart, ListEnd) cls iAm2 := iAm put "List: " OutName (ListEnd, iAm) put "Which Contestant do you want to elliminate?" get sNames %delete put "Backup : " bOutName (bListEnd, iAm2) put "Remaining: " OutName(ListEnd, iAm)

Please specify what version of Turing you are using
4.1.1

[[Gandalf]]

Well first thing's first, have you investigated this problem yourself? Linked lists are very common, and there are plenty of resources on just about anything to do with them.

Here's a quick link from Google which might help on delete: http://www.cs.bu.edu/teaching/cs112/spring-2000/linked-list-delete/

This is a great way to learn/practice recursion, so try to follow that route. Just go slowly, case-by-case, and ensure that each piece of code you write is accurate.

[imbored]

yea i saw that before but i dont know how to program it... i dont get the C++ codes

[[Gandalf]]

Perhaps try the following site instead, particularly the "modifying lists" section. It may even "convert" you to Python, given that Turing is a very ugly language in which to write linked lists.

http://ada.rg16.asn-wien.ac.at/~python/how2think/english/chap17.htm

Try to generalize what they do for the 2nd element of a linked list to an arbitrary element. I'm sure you can find something to clarify the concept. If you have any specific questions, you can then post them here.

[imbored]

this site is better but reguarding the converting... i can't do that. This is part of an assignment. i was suppose to use pascal but it wasn't working on my computer so i used turing which is already on my computer. Though this site looks alot more helpful i really dont fully understand it. I dont understand how to shift the pointer because i dont fully understand the functions regarding the pointer.

edit : okay nvm.. i read it a few times... and i dont get it lol.