Linked lists

[tziny]

Hello,

I am new to C++ programming. I have started learning by myself a couple of weeks ago. I have written the following program for generating linked lists but i am getting an error i dont understand. Can you please have a look at it?

#include<stdlib.h>
#include<stdio.h>
#include <iostream>
using namespace std;


struct node
{ char name[20];
node *nxt; // Pointer to next node
};


node add_node (node * x)
{


x = new node;
cout << "Please enter the name of the person: ";
cin >> x->name;
x->nxt = NULL;
return * x;


}


int main() {
node * head, * current;
int i;

head = NULL;

i = 0;
while (i < 5){
* current = add_node(current);

if (head == NULL){
head = current;
}
current = current->nxt;
i = i + 1;
}
return 0;
}


thanks!

[hamsterman]

The problem is in function add_node.
x is just a copy of current, so new changes the value of x but not the value of current. You can either make x a node** (then there is no point in returning anything), or make add_node return a node* (then it won't need any parameters).

Hope this helps.

By the way, next time use code tags and say what was the error message.

[tziny]

Thanks for the reply but i still dont get it. I tried something else now but it doesnt work. I dont get an error message but I think i only create the first node of the list and nothing else. Thanks again!

#include<stdlib.h>
#include<stdio.h>
#include <iostream>
using namespace std;


struct node
{ char name[20];
node *nxt; // Pointer to next node
};


node add_node (node * x)
{


cout << "Please enter the name of the person: ";
cin >> x->name;
x->nxt = NULL;
return * x;


}

void print_lists(node * head){
while (head != NULL){

cout << head->name;
head = head->nxt;
}
}

int main() {
node * head, * current;
int i;

head = NULL;

i = 0;
while (i < 5){

current = new node;
* current = add_node(current);
if (head == NULL){
head = current;
}
current = current->nxt;
i = i + 1;
}
print_lists(head);
return 0;
}

[hamsterman]

Very similar problem here as before.
current = current->nxt;
In this line you set current to the value of current->nxt ( which is null ).
current = new node;
In this line you set current to the address of a new node, but that doesn't affect current->nxt.

I suggest you do something like this in the loop:

if(head == NULL){
    head = new node;
    add_node(head);
    current = head;
}else{
    current->nxt = new node;
    add_node(current->nxt);
    current = current->nxt;
}

Here current always points to an existing node, and its value is not affected by new.

Also, in function add_node you already modify the node pointed by x, so there is no point to do so by returning something.