[HELP] reading txt file to a single linked list.

Question

hur1214 0 Newbie Poster

15 Years Ago

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

struct phonenode{
	char surname[15];
	char initals[4];
	phonenode *next;
};

phonenode *start_ptr = NULL;
phonenode *crrnt_ptr;


void read_txt(){

	ifstream ifs("test.txt");
	char surn[15];
	char inital[4];
	phonenode *temp1, *temp2;
	temp1 = new phonenode;
	if (ifs.fail()){
		cout << "ERROR" << endl;
	}
	while(ifs.good()){
		ifs>>surn>>inital;
		if(ifs.fail()){
			break;
		}
		surn >> temp1->surname;
		inital >> temp1->initals;

		if (start_ptr == NULL){
			start_ptr = temp1;
			crrnt_ptr = start_ptr;
		}

		else{
			temp2 = start_ptr;
			while (temp2->next != NULL){
				temp2 = temp2->next;
			}
			temp2->next = temp1;
		}

	}
	ifs.close();
	
}

void main(){
	read_txt();
	system("PAUSE");
}

above code is mine.. and I'm new to C++.

in "test.txt"

abcd      H.J.
efc       K.W.

I want to read text and want to put in linked list; however, I got some errors
error C2296: '>>' : illegal, left operand has type 'char [15]'
error C2297: '>>' : illegal, right operand has type 'char [15]'
error C2296: '>>' : illegal, left operand has type 'char [4]'
error C2297: '>>' : illegal, right operand has type 'char [4]'

sorry for noob question but... how can I fix these problem?

c++

3 Contributors
10 Replies
6K Views
3 Years Discussion Span
Latest Post 11 Years Ago Latest Post by kjr247

Ancient Dragon 5,243 Achieved Level 70

15 Years Ago

lines 31 and 32: what are you attempting to do there? chara arrays do not have overloaded operators such as >> If you want to copy the arrays then use strcpy() function. Either read your textbook or google to find out how to use that function.

Edited 15 Years Ago by Ancient Dragon because: n/a

Ancient Dragon 5,243 Achieved Level 70

15 Years Ago

Note that you have to allocate a new node on each iteration of the file read.

while( fd >> surn >> initial)
{
       temp1 = new phonenode;
       strcpy(temp1->surn, surn);
       strcpy(temp1->initial, initial);
       if( start_ptr == NULL)
      {
             // Add new node to the head of the linked list
      }
      else
       {
            // add new node to the tail of the linked list
       }
}

}

Edited 15 Years Ago by Ancient Dragon because: n/a

Ancient Dragon 5,243 Achieved Level 70

15 Years Ago

you forgot to initialize temp->next = NULL; at between lines 28 and 29, so at line 37 it can not find the last node.

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hur1214 0 Newbie Poster · Answer 1 · 2009-10-05T06:17:15+00:00

lines 31 and 32: what are you attempting to do there? chara arrays do not have overloaded operators such as >> If you want to copy the arrays then use strcpy() function. Either read your textbook or google to find out how to use that function.

I just want to put values into linked list(surname and initals) from the text file.. okay I will try strcpy() function! :p

thanks!

hur1214 0 Newbie Poster · Answer 2 · 2009-10-05T06:33:10+00:00

strcpy(temp1->surname, surn);
		strcpy(temp1->initals, inital);

hmmmm... gave me error....

from the test.txt,
"abcd" into linked list(phonenode), surname and
"H.J." into initals.

how can I do this.... :(

hur1214 0 Newbie Poster · Answer 3 · 2009-10-05T07:26:51+00:00

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

struct phonenode{
	char surname[15];
	char initial[4];
	struct phonenode *next;
};


phonenode *start_ptr = NULL;
phonenode *crrnt_ptr;


void read_txt(){

	ifstream ifs("test.txt");
	char surname[15];
	char initial[4];
	phonenode *temp1, *temp2;
	temp1 = new phonenode;
	if (ifs.fail()){
		cout << "ERROR" << endl;
	}
	while( ifs >> surname >> initial){
		temp1 = new phonenode;
		strcpy(temp1->surname, surname);
		strcpy(temp1->initial, initial);
		if (start_ptr == NULL){
			start_ptr = temp1;
			crrnt_ptr = start_ptr;
		}
		else{
			temp2= start_ptr;
			while (temp2->next != NULL){
				temp2 = temp2->next;
			}
			temp2->next = temp1;
		}

	}
}

void main(){
	read_txt();
	system("PAUSE");
}

it comples but give
"Unhandled exception at 0x013f16ba in phonecompany.exe: 0xC0000005: Access violation reading location 0xcdcdcde1."

do I have to use ()malloc()? or something like that?

else{
			temp2= start_ptr;
			while (temp2->next != NULL){
				temp2 = temp2->next;
			}
			temp2->next = temp1;
		}

seems there are some errors. ummm, but I dont know what is wrong..

hur1214 0 Newbie Poster · Answer 4 · 2009-10-05T08:13:33+00:00

you forgot to initialize temp->next = NULL; at between lines 28 and 29, so at line 37 it can not find the last node.

oh yes. I fixed that and sadly another error!
"Run-Time Check Failure #2 - Stack around the variable 'initial' was corrupted."

omg.... linked list is soo difficult..

is doing something like

ifs >> tempsur >> tempini

bad thing?

hur1214 0 Newbie Poster · Answer 5 · 2009-10-05T08:15:58+00:00

I just re-started my computer and it works w/o any errors..
omg...

Thanks, Ancient Dragon.
YOU ARE MY HERO!

kjr247 0 Newbie Poster · Answer 6 · 2012-11-21T06:00:26+00:00

awesome I love how problems are marked solved with no posted solution.. thanks for wasting internet space with half finished code...

kjr247 0 Newbie Poster · Answer 7 · 2012-11-21T19:57:20+00:00

I apologize for my previous post.. I'm new to using this site. I was rather angry at the internet for 10 more incomplete websites and threads just like this one.