linked list - Can't get LinkedList implementation to work (Python) -

i felt should make question earlier today, because problem different before. , wanted leave other question reference. pretty cluttered. if problem, let me know.

from can tell, nothing added linked list. doesn't print or give me errors, , problem. it's supposed insert words alphabetically. seems logical me. redid of insert().

i feed files single words on each line. functions of list insert , print. example text (not including blank lines):

here code:

import sys, os, copy, fileinput class node:     def __init__(self, word):         self.data = word         self.next = none     def nextnode(self):         if self.next not none:             return self.next         else:             return none     def getdata(self):         return self.data     def setnext(self, node):         self.next = node     def hasnext(self):         if self.next == none:             return false         else:             return true  class linked_list:     def __init__(self):         self.head = node(none)         self.isempty = true     def insert(self, word):         newnode = node(word)         #look position insert:          #when empty         if self.isempty == true:             self.isempty = false             self.head = newnode         #when has more 2 nodes          else:             prev = none             current = self.head             nextfound = false #the next current when less node              while nextfound == false , current != none:                 if current.getdata() < newnode.getdata():                     prev = copy.copy(current)                     current = current.nextnode()                 else:                     nextfound = true              if prev == none:                 nextnode = copy.copy(current)                 self.head = newnode                 self.head.setnext(nextnode)             else:                 prev.setnext(newnode)                 newnode.setnext(current)      def printlinkedlist(self):         if self.head.getdata() == none:             print("the file empty.")         else:             prints = self.head             while prints.hasnext():                 sys.stdout.write(prints.getdata() + '\n')                 prints.setnext(prints.nextnode())  linkedlist = linked_list()  wordlist = ["hello", "jupiter", "albacore", "shrimp", "axe"] line in wordlist:     linkedlist.insert(line) linkedlist.printlinkedlist() 

the problem you're making copy of previous node here:

prev = copy.copy(current) 

so, when update copy in-place here:

prev.setnext(newnode) 

… doesn't affect original node that's linked list. (nor replace original node modified copy.) so, nothing ever gets changed.

to fix it, remove copy.copy.

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when fix that, there's bug in code lead infinite loop of printing out "absolute", in printlinkedlist:

prints.setnext(prints.nextnode()) 

this doesn't useful—it sets prints.next prints.next. crucially, doesn't update variable prints point next node. this:

prints = prints.nextnode() 

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and both of changes, output original example is:

absolute crisp daytona demand 

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however, notice new example missing 1 value:

albacore axe hello jupiter 

i'll leave figure out shrimp went. (you can post new question if stuck.)

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if you're wondering how found problem:

i added print statement after while loop dumps out bunch of information found previous node, including id, , print before , after setnext, see setting next member of first node each time through loop, different first node each time through.

then added print show me id of each nodes, , clear found previous node each time wasn't of nodes in list. @ point copy.copy jumped out @ me.