0

Hey, Im having some trouble with linked lists, I have been givin a task where I am asked to crreate a linked list which reads in a random set of chars from a .txt file and stores them in a linked list, then prints them out in a seperate function.

here is my code

#include <iostream>
#include <fstream>

using namespace std;

struct node
{
	char base;
	node* next;
};

void initialise(node*& head);
void read(node*& head);
void print(node*& head);

int main()
{
	node* head = NULL;
	
	cout << "Set linked list to NULL" << endl;
	initialise(head);

	cout << "Reading from file into linked list" << endl;
	read(head);

	cout << "Printing out linked list" << endl;
	print(head);

	return 0;
}
void initialise(node*& head)
{
	head = NULL;
}
void read(node*& head)
{
	node* temp;
	char filename[40];
	ifstream ins;

	cout << "Filename: ";
	cin >> filename;

	ins.open(filename, ios::in);
	temp = new node;
	if (temp == NULL)
	{
		cout << "An error occured: " << endl;
		exit(0);
	}
	if(ins.good())
	{
		while(!ins.eof())
		{
			ins >> temp->base;
			temp->next = NULL;

			if (head == NULL)
				head = temp;
			else
			{
				node* z;
				z = head;
	
				while (z->next != NULL)
				{
					z = z->next;
				}
				z->next=temp;
			}
		}
	}
}
void print(node*& head)
{
	node* temp;
	temp = head;
	while (temp != NULL)
	{
		cout << temp->base << endl;
		temp = temp->next;
	}
}

text file contains random chars, like "AINFUEH EIUDNUIEW IWEUNF" and whitespaces are ignored.

for some reason, when it prints out, it gets stuck in a loop and only prints out the last char in the text file over and over...

can someone please tell me what im doing wrong?

2
Contributors
2
Replies
4
Views
8 Years
Discussion Span
Last Post by opposition
Featured Replies
  • Looks to me like no new nodes are created in this loop: [code=cplusplus] while(!ins.eof()) { ins >> temp->base; temp->next = NULL; if (head == NULL) head = temp; else { node* z; z = head; while (z->next != NULL) { z = z->next; } z->next=temp; } } [/code] You are … Read More

1

Looks to me like no new nodes are created in this loop:

while(!ins.eof())
		{
			ins >> temp->base;
			temp->next = NULL;

			if (head == NULL)
				head = temp;
			else
			{
				node* z;
				z = head;
	
				while (z->next != NULL)
				{
					z = z->next;
				}
				z->next=temp;
			}
		}

You are just continually putting a new value into temp->base and overwriting the old value. As for the infinite loop, I haven't tested it out, but I'm guessing that temp == temp->next and possibly head == temp. You need to create a new node every time you read a new value from the input file.

Comments
the OP said: "+rep", so I thought I'd make it happen :)
0

You are just continually putting a new value into temp->base and overwriting the old value.

haha thank you very much, that was exactly my problem, I originally had it reading from cin, and forgot to move my new node line into the eof loop, works perfectly now :)

+rep :)

This article has been dead for over six months. Start a new discussion instead.
Be sure to adhere to our posting rules.