Searching text file with prefix

[trno224]

I am writing a program that reads in a text file that has a name of something, and a weight associated with that name and and stores it in a linked list and sorts it based on the weight and by the name in it. That part is working but I also need to create a function that sorts thru the file and finds every word that starts with a prefix that is entered by the user. For example if the user enters "Am" the function will search the file and return every word that starts with "Am". Anyways I have never done anything like this before and so any help on how to do this would be greatly appreciated!

Here is the Program thus far...
Header file:

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

//declare node structure
struct node
{
	//declare string text
	string text;
	//string name;
	int number;
	//declare next and prev node
	struct node *next;
	struct node *prev;
}*start; //start or head of linked list


//delcare class LinkedList
class Term
{
	//public part
public:
	//declare all fucntions
	//this will create linked list
	void CreateList(string file);
	//insert a line at end of list
	void InsertAtEnd(int num,string file, int size);
	void print(string file_name);
	void sort_weight ();
	void sort_query();
	//void SelectionSort();
	//void swap(node *p1, node*p2);

	//private
private:
	//declare head and tail
	node *head;
	node *tail;
};

Functions and main:

#include "Term.h"

void Term :: CreateList(string file)
{
	//delclare node temp.
	node *temp;
	//initialize temp
	temp = new(struct node); 
	//set text(which was declared in class) to file.
	temp -> text = file;
	temp -> next = NULL;

	//If start of list equals NULL enter statement.
	if (start == NULL)
	{
		temp -> prev = NULL;
		//set beginning of list to temp.
		start = temp;
	}
	//if not enter else statement.
	else
	{
		//enter loop if the term after start is not NULL.
		while (start -> next != NULL)
		{
			//set start equal to line proceeding it.
			start = start -> next;
			//set that line equal to temp.
			start -> next = temp;
			//set previous line equal to start.
			temp -> prev = start;
		}
	}
	//End function and return too main.
}
//Creat function that insert something at end of file taking parameters file(content of file), and size(number of lines).
//This function will enter lines into list but reorder them since orginally it insert backwards and finally it will insert new line.
void Term :: InsertAtEnd(int num, string file, int size)
{
	//Declare nodes temp and temp_2.
	struct node *temp, *temp_2;
	//set temp_2 to beginning of list(start).
	temp_2 = start;

	//if you have not reached the end of the file enter loop and do not exit till you reach end of file.
	for (int i = 0; i < size; i++)
	{
		//progress through loop.
		temp_2 = temp_2 -> next;
	}
	//initialize temp.
	temp = new(node);
	temp -> text = file;
	temp -> number = num;

	//if line following q equals NULL enter
	if (temp_2 -> next == NULL)
	{
		//progress q and set equal to tmp.
		temp_2 -> next = temp;
		//set line following tmp to NULL.
		temp -> next = NULL;
		//set line Proceeding tmp to temp_2.
		temp -> prev = temp_2;      
	}

	//if not enter if statement
	else
	{
		//set line following tmp equal to line following temp_2.
		temp -> next = temp_2 -> next;
		temp -> next -> prev = temp;
		temp_2 -> next = temp;
		temp -> prev = temp_2;
	}
}


void Term :: sort_weight ()
{
	node * temphead = start;
	//ListNode * tempnode = NULL;
	int temproll;
	string tempname;
	int counter = 0;
	while (temphead )
	{
		temphead = temphead->next;
		counter++;
	}
	temphead = start -> next;
	
	for (int j=0; j<counter; j++)
	{
		while (temphead->next)  //iterate through list until next is null
		{
			if (temphead->number < temphead->next->number)
			{
				/*tempnode = temphead;
				temphead = temphead->next;
				temphead->next = tempnode;*/
				temproll = temphead->number;
				temphead->number = temphead->next->number;
				temphead->next->number = temproll;

				tempname = temphead->text;
				temphead->text = temphead->next->text;
				temphead->next->text = tempname;
				temphead = temphead->next;//increment node
			}
			else 
				temphead = temphead->next;//increment node
		}	
		temphead = start;//reset temphead
	}
}

void Term :: sort_query ()
{
	node * temphead = start;
	//ListNode * tempnode = NULL;
	string temp;
	int temp_2;
	int counter = 0;
	while (temphead)
	{
		temphead = temphead->next;
		counter++;
	}
	temphead = start -> next;
	
	for (int j=0; j<counter; j++)
	{
		while (temphead->next)  //iterate through list until next is null
		{
			if (temphead->text > temphead->next->text)
			{
				/*tempnode = temphead;
				temphead = temphead->next;
				temphead->next = tempnode;*/
				temp = temphead->text;
				temphead->text = temphead->next->text;
				temphead->next->text = temp;

				temp_2 = temphead->number;
				temphead->number = temphead->next->number;
				temphead->next->number = temp_2;
				temphead = temphead->next;//increment node
			}
			else 
				temphead = temphead->next;//increment node
		}	
		temphead = start;//reset temphead
	}
}
//Declare void function(does not return anything) that will print the current linked list to the screen when requested
//or output it to the input file when requested.  It takes parameters letter(letter entered when prompted in main function) and file_name
//(name of file).
void Term :: print(string file_name)
{
	//declare and initialize line_number.
	int line_number = 1;
	//declare node temp_2
	node *temp_2;
	//set equal to start or beginning of list
	temp_2 = start;

	//if first line is equal to blank space enter statement
	if( temp_2->text == "")
	{
		//proceed to followinf line skipping over this plan line
		temp_2 = temp_2-> next;
	}

	//enter loop if temp_2 != null (have not reached end of file)
	while (temp_2 != NULL && temp_2-> text != "")
	{
		//output line number and each line in the list till you reach the end
		cout << temp_2 -> number << " " << temp_2 -> text << endl;
		//progress to next line
		temp_2 = temp_2 -> next;
		//increment line number
		line_number += 1;
	}
	
}

int main()
{
	Term txt_file;
	string file;
	int num;
	string file_name;
	ifstream infile;
	int size = 0;
	int largest_pos = 0;
	//call function to create list
	txt_file.CreateList(file);
	
	//ask user for file to open and store in variable
	cout << "What file would you like to open: ";
	getline(cin, file_name);
	infile.open(file_name);
	
	//check if file name is valid
	if(infile.fail())
	{
		//if not display error message and end program
		cout <<"The file cannot be opened, terminating program!" << endl;
		system("pause");
		exit(0);
	}

	//use loop to read through file
	while(infile >> num && (getline(infile, file)))
	{

		//call function to insert each line in file into linked list one following the other
		txt_file.InsertAtEnd(num,file, size);
		//increase size
		size += 1;
		//increase largest_pos
		largest_pos += 1;
	}

	txt_file.sort_weight();
	txt_file.print(file_name);
	cout << endl << endl << endl;
	txt_file.sort_query();

	//call function to print current file to screen
	txt_file.print(file_name);
	system("pause");
	return 0;
}

Here is a snippet from one of the text files:

4551	Pinnacle West Capital
7018	Automatic Data Proc.
8969	Continental Airlines
5725	PPL
1193	Goody's Family Clothing
1694	Community Health Sys.
7875	Cenex Harvest States
5723	Air Products & Chem.
2238	Consol. Freightways
31138	Goldman Sachs Group
2352	PNM Resources