Linked List Structure Using Classes

[L Plate]

For my next lab test I am required to write a DNS storage and retrival program using classes and a linked list structure. The program is required to take an ip and url pair from the command line and add them to the linked list. The Letter A denotes the ip and url pair which is to be added to the list eg:

A www.google.com 64.125.19.2

The program is also required to find specific ip's, defined by the letter I, and print out the corresponding url, find specific url's, defined by the letter U and print out the corresponding ip, print out the number of ip and uri pairs in the list, defined by the letter N and delete uri's and it's corresponding ip, defined by the letter D.

The issue I am currently having is that I am trying to use one function to search for an url and it's ip and search for an ip and it's url. For example, if I were to type in the following into the command line:

U www.google.com

the answer would be 64.125.19.2.

Likewise:

I 64.125.19.2

would give an answer www.google.com

However, if I were to type "I www.google.com" the answer I get is www.google.com, when I should be getting "nil" instead. The simplest solution would be to simply make two seperate functions but I would like to know if it's possible to do it with one function. My code is as follows:

#include <iostream>
#include <cstdlib>

using namespace std;

class ip_uri_store
 {
	public:
	ip_uri_store(string add_uri, string add_ip);
	ip_uri_store* find(string target);
	string uri_found();
   	string ip_found();
	void delete_item();

	private:
	string uri;
	string ip;
	ip_uri_store *next;
 };

ip_uri_store *list_head = NULL;
int n=0;

ip_uri_store::ip_uri_store(string add_uri, string add_ip)
{
	uri = add_uri;
	ip = add_ip;
	next = list_head;
	list_head = this;
	n=n+1;
}

void delete_item()
{
//To be my delete function. I've having trouble trying to figure this out.
//I was planning on writing the program by incorporating the data into a 
//"struct" to make it easier to manipulate data for deleting items
//but the data needs to be protected, hence it's current format.
//If anyone has any suggestions I would appreciate it.
}

//the following is the url-ip search function I was talking about
ip_uri_store* ip_uri_store::find(string target)
{
	if (uri == target || ip == target)
	return(this);
	if (next == NULL)
	return(NULL);
	return(next->find(target));
}

string ip_uri_store::uri_found()
{ return(uri) ;
}

string ip_uri_store::ip_found()
{ return(ip) ;
}


int main(int argc, char *argv[])
{
	if (argc == 1)
	{
	cout << "No Parameters"<< endl ;
	return(0) ;
	}

	ip_uri_store *found;

	for(int i=1; i<argc; i++)
	{

	if(strlen(argv[i]) == 1)
	{
		char options;
		options = *argv[i];
		switch(options)
        	{
		case 'A':
		new ip_uri_store(argv[i+1], argv[i+2]);
		break;

		case 'D':
		
		break;

		case 'U':
		found = list_head->find(argv[i+1]);
		if ( found != NULL)
		cout <<  found->ip_found() << endl ;
		else cout << "nil" << endl;
		break;

		case 'I':
		found = list_head->find(argv[i+1]);
		if ( found != NULL)
		cout <<  found->uri_found() << endl ;
		else cout << "nil" << endl;
		break;

		case 'N':
		cout << n <<endl; break;

		case 'T': break;
		case 't': break;
		default: cout << "command error" << endl; return(0);
        	}
	}

	}

	return(0);
}

[jsmith]

You would have to add a second parameter to find() to tell it which field to look at (URL or IP) and then only look at the one field instead of both.

[Hammurabi]

Are you sure these commands are supposed to come from the command line? If so, is this how you would run it (assuming the program is called ip_uri)?

ip_uri A www.google.com 1.2.3.4 A www.yo.com 5.6.7.8 U www.google.com I 5.6.7.8

That seems a little odd to me. Usually you would take the commands from the command line (and/or from a redirected text file).

[L Plate]

Yes, the program is run as you described. The ouput would be:

1.2.3.4
www.yo.com