graph help please

[shamslam845]

hello. I need help. I got this graph code and it requires a file like a .txt i guess. I am not sure what the file should look like to make it work. I want to add weighted edges. Does anyone know?

#include <stdlib.h>
#include <limits.h>
#include <ctype.h>
#include <iostream>
#include "strings.h"
typedef char *charptr;

strings::~strings()
{ for (int i=0; i<n; i++) delete[](p[i]);
delete[]p;
}

int strings::add(const char *s)
{	int i;
for (i=0; i<n; i++) if (strcmp(p[i], s) == 0) return i;
if (n == N)
{	char **pOld = p;
p = new charptr[N += ChunkSize];
for (i=0; i<n; i++) p[i] = pOld[i];
delete[]pOld;
}
p[n] = new char[strlen(s) + 1];
strcpy(p[n++], s);
return n - 1;
}

int strings::read(istream &f)
{	char buf[100];
f >> setw (100) >> buf;
return f.fail() ? -1 : add(buf);
}

struct edge{int num, len; edge *next;};

class graph	{
public:
	int n, N, start, finish, nInS, undirected;
	void build(strings &T, ifstream &file);
	void output(const strings &T) const;
	int length(int i, int j) const;
	void prepare();
	void ExpandSetS();
private:
	struct NodeType{ int count, D, connect, inS; edge *link;}
*list;
enum {nil=-1, inf=INT_MAX/2};
int ReadName(strings &T, istream &file, char &PrevChar);
};

void error(const char *s)
{	cout << s << endl; exit(1);
}

int graph::ReadName(strings &T, istream &file, char &PrevChar)
{	
	char s[100];
	s[0] = '\n';
	do
	{	PrevChar = s[0];
	file.get(s[0]);
	}
	while(!file.fail() && !isalpha(s[0]));
	if (file.fail()) return -1;
	file >> setw(99) >> &s[1];
	return T.add(s);
}

void graph::build(strings &T, ifstream &file)
{	int i, j, len;
	edge *p;
	char PrevChar;
	const int ChunkSize = 64;
	N = n = 0;
	list = NULL;
	for (;;)
	{ j = ReadName(T, file, PrevChar);
	if(j < 0) break;
	if (PrevChar == '\n')
	{	i=j;
	j = ReadName(T, file, PrevChar);
	}
	file >> len;
	if (file.eof()) break;
	if (file.fail())
		error("Incorrect input file.");
	int max = i > j ? i : j;
	if (max >= N)
	{ 
		NodeType *listOld = list;
		list = new NodeType[N += ChunkSize];
		for (int v=0; v<N; v++)
		if(v < n)
			list[v] = listOld[v];
		else
		{
			list[v].count = 0;
			list[v].link = NULL;
		}
		delete[]listOld;
	}
	if (max >= n) n = max + 1;
	p = new edge;
	p->num = j; p->len = len;
	p->next = list[i].link;
	list[i].link = p;
	list[j].count++;
	//Undirected graph: add <j, i> besides <i, j>
	if (undirected)
	{
		p = new edge;
		p->num = i;
		p->len = len;
		p->next = list[j].link;
		list[j].link = p;
		list[i].count++;
	}
	}
	file.close();
}
int graph::length (int i, int j) const
{
	edge *p= list[i].link;
	while (p)
	{
		if (p->num == j)
			return p->len;
		p = p->next;
	}
	return inf;
}

void graph::prepare()
{
	for(int v = 0; v<n; v++)
	{
		list[v].D = (v== start ? 0 : length(start, v));
		list[v].inS = 0;
		list[v].connect = start;
	}
	list[start].inS = 1;
	nInS = 1;
}

void graph::ExpandSetS()
{
	int v, w = inf, min = INT_MAX;
	// choose a vertex w in V such that list[w].D
	// is a minimum
	for(v=0; v<n; v++)
		if (list[v].inS == 0)
		{
			int sum = list[w].D + length(w, v);
			if (sum < list[v].D)
			{
				list[v].D = sum;
				list[v].connect = w;
			}
		}
}

void graph::output(const strings &T) const
{
	if (list[finish].D == inf)
	{
		cout << "No path from start to finish. \n";
		return;
	}
	//Replace predecessors with successors
	int j = finish, i , jnext = 0;
	for(;;)
	{
		i=list[j].connect;
		list[j].connect = jnext;
		if (j == start) break;
		jnext = j;
		j = i;
	}
	cout << "Shortest path: \n\n";
	i = start;
	cout << "			Vertex					Distance\n";
	for(;;)
	{
		cout << (i == finish ? "finish = " :
			i == start ? "start = " :
			"			")
			<<setw(20) << setiosflags(ios::left) << T[i] << "   "
			<< setw(6) << resetiosflags(ios::left) << list[i].D
			<< endl;
	if (i == finish)
		break;
	i = list[i].connect;
	}
}

int main()
{
	graph g;
	strings T;
	char fname[50], ch;
	cout << "Input file: ";
	cin >> setw(50) >> fname;
	ifstream file(fname, ios::in);
	if(file.fail())
		error("Cannot open input file.");
	cout << "Is the graph Directed or Undirectes? (D/U) ";
	cin >> ch;
	g.undirected = (ch == 'u' || ch == 'U');
	g.build(T, file);	//build adjacency lists
	cout << "Vertices:";
	int n = T.size();
	for(int i = 0; i<n; i++)
	{
		if(i % 5 == 0)
			cout << endl;
		cout << T[i] << " ";
	}
	do
	{
		cout << "\nEnter start and finish:\n";
		g.start = T.read(cin);
		g.finish = T.read(cin);
		if (g.start >= g.N || g.finish >= g.N)
			cout << "Incorrect start or finsih.\n";
			else
			{
				g.prepare();
				while (g.nInS < g.N)
					g.ExpandSetS();
				g.output(T);
			}
			cout << "Do you want another path? (Y/N) ";
			cin >> ch;
	} while (ch == 'y' || ch == 'Y');
	return 0;
}

thanks