Hi, I have to write an assignment in C++ for my programming class. This is the f

Question

Hi, I have to write an assignment in C++ for my programming class. This is the first part of the assignment and I am having trouble writing it. Please help me!!

In this assignment, you are to build singly linked lists, according to the given criteria.
The structure is defined as
struct Node {
string name;
long ID;
Node * next;
};


This assignment includes:
1. Write a function that will read from a file with the filename as the parameter of the function. In the function, it will do:
a. Read one person’s information at a time, and build a singly linked list according to the ascending order of the person’s ID.
Result: a singly linked list should have its first node to store the info with the smallest ID value, the second node to store the info with the next smallest ID value, and so on.
b. Pass out the head pointer as in return.

This is the file:

AprilJoe 129013
MatthewsJocob 399921
GarfieldKitty 332901
LakeBill 211254
JonesBetty 182890
GoodmanBetty 195106
LandsNorman 365920
JohnsonCarl 297192



This is how I would think to write it. First I used the a read function, the I sorted it using bubblesort and then I would read it again. Here is what I have so far.



#include <iostream>
#include <fstream>
#include <string>


using namespace std;


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


Node * read (string fileName);
void print(Node * list);



int main()
{
Node * list;
list = read("a9.txt");
print(list);









system ("PAUSE");
return 0;
}






Node * read (string fileName)
{
Node * list = NULL;
Node * cur = NULL;

ifstream myfile;
myfile.open("a9.txt");
if(!myfile.is_open())
{
cout << "Cannot open " << fileName << endl << endl;
return NULL;
}

string garbage;
while (!myfile.fail())
{
Node * temp = new Node();
getline(myfile, temp->name);
myfile >> temp->ID;
getline(myfile, garbage);
getline(myfile, garbage);

temp->next = NULL;

if (list == NULL)
{
list = temp;
}

if (cur == NULL)
{
cur = temp;
}
else
{
cur->next = temp;
cur = cur->next;
}
}
myfile.close();
return list;
}

void print(Node * list)
{

Node * cur = list;
while(cur != NULL)
{
cout << "Name: " << cur->name << endl;
cout << "ID: " << cur->ID << endl;
cur = cur->next;
}
}

void sort(node * next)
{
int x;
int y;
int temp;
node * next;

for(x=size; x>0; x--)
{
for(y=0; y<x-1; y++)
{
if(node->name>node->name)
{
temp = node -> name;
node -> name = node -> name;
node -> name = temp;
}

}
}
cout << "SORTED LIST ACCORDING TO ID NUMBERS:" << endl << endl;
for (int i = 0; i < size; i++)
{
cout << "Name: " << node -> name<< endl;
cout << "ID: " << node -> ID << endl;
}
}

Explanation / Answer

Hope this helps. Let me know if you have any questions. I changed a few things. Rather than reading, sorting it, and then reading it again, I opted to keep it sorted as it is read in. To do this, when you read a new record, instead of just inserting it at the end of the linked list, insert it where it should be in the sorted list. Also, the input parsing wouldn't work for the file given. I assume the file will be different, like: AprilJoe 129013 MatthewsJocob 399921 ... instead of all on one line? If it is all on one line, then the input parsing (the "getline"s) will have to change. I just left it as is. :) Here it is with inserting it into the linked list in sorted order. #include #include #include using namespace std; struct Node { string name; long ID; Node * next; }; Node * read (string fileName); void print(Node * list); int main() { Node * list; list = read("a9.txt"); print(list); system ("PAUSE"); return 0; } Node * read (string fileName) { Node * list = NULL; Node * cur = NULL; ifstream myfile; myfile.open(fileName.c_str()); if(!myfile.is_open()) { cout next = cur; list = temp; } // otherwise, we compare it to the next element to determine where it should go else { bool inserted = false; // run through the whole list to determine where it should go while (cur->next != NULL) { if (temp->ID next->ID) { temp->next = cur->next; cur->next = temp; inserted = true; break; } cur = cur->next; } // if we haven't inserted it, then it goes at the end, where cur->next now points if (inserted == false) { cur->next = temp; } } } getline(myfile, name); } myfile.close(); return list; } void print(Node * list) { Node * cur = list; while(cur != NULL) { cout

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