C++ linked list project

[boyracer87]

Hey guys,

Im doing a project for collage and i am running into a few difficulties. i have to be able to go back and forwards through a list by using the "f" and "r" keys. iv hacken out a bit of code to do go right but i have to pass it by reference in order to get it to work, which only ends up changing the head and causing a load of side effects. as far as going left is concernds, it doesent work at all!!


Here is the full code:
The functions i am having trouble with are called "moveright" and "moveleft".

#include <iostream>
#include <conio.h>
#include <string>

using namespace std;

struct Node {
	string data;
	struct Node * next;
	struct Node * prev;
};
typedef struct Node entry ;


string UCase(string s);
void list(entry * H);
void del(entry * H,string OldName);
void rename(entry * H, string old, string newname);
void moveright(entry *&H);
void Head(entry * H);
void tail (entry * H);
void moveleft(entry * H);
void inalpha(string newname, entry * &H);

main()
{	entry *head=NULL, *pos=head;
 	string Command,OldName,NewName ;
	do {
		cout << "Next Command? " ;
		cin >> Command ;
		Command = UCase(Command) ;
		if(Command == "L") {
			moveleft(head);
		} else if(Command == "R") {
			moveright(head);
		} else if(Command == "H") {
			Head(head);
		} else if(Command == "T") {
			tail (head);
		} else if(Command == "RENAME") {
			cout << "OldName? " ;
			cin >> OldName ;
			cout << "NewName? " ;
			cin >> NewName ;
			rename(head,OldName,NewName);
		} else if(Command == "NEW") {
			cout << "Name? " ;
			cin >> OldName ;
			inalpha(OldName, head);		
		} else if(Command =="DELETE") {
			cout << "Name? " ;
			cin >> OldName ;
			del(head,OldName);
		} else if(Command == "LIST") {
			 list(head);
		}
	}while(Command != "END") ;
}

string UCase(string s)
{	int i ;
	for(i=0 ; i < s.length() ; i++) {
		s[i] = toupper(s[i]) ;
	}
	return s;
}

		  
void list(entry * H)
{	entry *pos = H ;
	while(pos != NULL) {
		cout << pos->data <<'\t' ;
		pos = pos->next ;
	}
	cout<<endl;	
}	

void del(entry * H,string OldName)
{	entry*pos, *prev, *firstEntry=H, *first;
	if(H != 0){
		prev=NULL;
		pos=H;
		while (pos != NULL && pos->data != OldName){
			prev=pos;
			pos=pos->next;
	}
		if(pos == NULL){
				cout<<"Name is not in the list"<<endl;
				//break;
		}else if(pos != NULL){
			if(prev == NULL){
				H = pos->next;
				delete pos;
				//break;
			}else{
				prev->next=pos->next;
				delete pos;
				//break;
			}
		}
		
	}	
}

void rename(entry * H, string old, string newname)
{	entry*pos=H;
	bool inlist(false);
	while (pos != NULL){
			if (pos->data != newname){
				pos=pos->next;
			}else if (pos->data == newname){
				inlist=true;
				break;
			}
		}	
	pos=H;
	while (pos != NULL){
		if(pos->data==old){
			if (inlist==false){
				pos->data=newname;
				break;
			}else if (inlist==true){
				cout<<"Already in list"<<endl;
				break;
			}
		}else{
			pos=pos->next;
		}

}
}


/*void moveright(entry * &H)
{	entry* current;
	current=H;
	if (current->next != NULL){
		H=current->next;
		cout<<current->data<<endl;
	}else{
		cout<<current->data<<endl;
		cout<<"End of list"<<endl;	
	}
}*/



void moveleft(entry * H)
{	entry *current, *T, *pre;
	current=H;
	if(current->prev != NULL){
		while(current->prev !=NULL){
			pre=current;
			current=current->next;
		}
		current=T;
		current->prev=pre;
		current=pre;
		cout<<current->data<<endl;
	}else{
		cout<<current->data<<endl;
		cout<<"Start of list"<<endl;
	}
}



void Head(entry * H)
{	cout<<H->data<<endl;
}


void tail (entry * H)
{	entry * pos=H;
	while (pos->next != NULL){
		pos=pos->next;
	}
		cout<<pos->data<<endl;
}	

void moveright(entry *&H)
{	entry *pos=H;
	if(pos != NULL){
		pos=pos->next;
		cout<<pos->data<<endl;
	}else{
		cout<<pos->data<<endl;
		cout<<"End Of List"<<endl;
	}
	H=pos;
}

void inalpha(string newname, entry * &H)								
{	entry *e, *pos=H, *prev ;
	bool inlist(false);
	while (pos != NULL){
		if (pos->data != newname){
			pos=pos->next;
		}else if (pos->data == newname){
			inlist=true;
			break;
		}
	}

	if(inlist==false){
		e=new entry;
		e->data=newname;
		e->next=NULL;
		if (H==0){
			H=e;
		}else{
			prev=NULL;
			pos=H;
			while(pos != NULL && pos->data <= newname){
				prev=pos;
				pos=pos->next;
			}
			if (prev == NULL){
				e->next=H;
				H=e;
			}else{
				e->next=prev->next;
				prev->next=e;
			}
		}
	}else if(inlist==true){
		cout<<"Sheet is already in the list"<<endl;
	}
}

has anybody got any idea as to how i can do this?

thanks,
Ray