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link list segmentation fault

krokus81 (1)
I know this will be a simple and stupid error that I'm missing. Line 75 ends up pointing to something that the debugger can't show me, and then I get a segmentation fault on the next line.

This is reading in a file with a name and an ID. It's then creating a link list sorted on name. (There is another one to be generated on the ID, but I can sort that out later.)

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#include <iostream>
#include <string>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <cstring>

using namespace std;

// delcare global variables

struct Node {
string name;
long ID;
Node * next;
};


string filename="a9.txt";

// prototype functions
Node * read (string);

int main()
{

// call functions
Node * entryPoint = read (filename); // call to read file, return linked list

return 0;
}

// read information from file
Node * read (string filename)
{
     Node * current= new Node;
     Node * head=current;
     Node * readBuffer = new Node;
     Node * pointer = new Node;
     Node * temp1 = new Node;
     Node * temp2 =new Node;


     int count=0;
     int i=0;
//     int stringCompA=0;
//     int stringCompB=0;
     char IDstring[100];

     ifstream fileRead;
     fileRead.open (filename.c_str()); // open file for reading 
     fileRead >> readBuffer->name;
     fileRead >> IDstring;
     current->ID=atoi(IDstring);
     fileRead >> pointer->name;
     fileRead >> IDstring;
     pointer->ID=atoi(IDstring);
//     fileRead >> pointer->ID;
     
//     stringCompA = strcmp(readBuffer->name,pointer->name);
        if(readBuffer->name > pointer->name)
        {
           head = pointer;
           current = readBuffer;
           head->next = current;
        }
        
        else
        {
            head = readBuffer;
            current = pointer;
            head->next = current;
        }
pointer = new Node;
current->next=pointer;
current = current->next;
current->next=NULL;

while (!fileRead.eof())
{
    temp1=current;
    temp2=temp1->next;
//     temp2=current->next;
     fileRead >> readBuffer->name;
     fileRead >> readBuffer->ID;


     // sort into name order
//        temp1=current->next;
//        stringCompA = strcmp(readBuffer->name,current->name);
//        stringCompB = strcmp(readBuffer->name,temp1->name);

        if (readBuffer->name < head->name)
        {
           temp1=head;
           head=readBuffer;
           head->next = temp1->next;
        }
        
        else if(readBuffer->name > current->name && readBuffer->name < temp2->name)
        {
          current->next = readBuffer;
          readBuffer->next = temp2;          
        }
        
        else if (readBuffer->name > current->name && current->next==NULL)
        {
          temp1=readBuffer;
          current->next = temp1;
          temp1->next=NULL;
        }
temp1=new Node;
current->next = temp1;
temp1->next=NULL;

    count++;
}


count--;
fileRead.close(); // close datafile

// output original file contents
     cout << "File contents in original format: " << endl << endl;

     current=head;

while(current->next!=NULL)
      {
      cout << current->name << " " << current->ID << endl;
      current=current->next;
      }

system ("Pause");
system("cls");

return head;
}


Thanks in advance.
Last edited on
kbw (9488)
A description of what you're trying to do along with a sample from the input file might help.
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