Declaration of variable, simple linked list - c

Question

#include <stdio.h>
#include <stdlib.h>
struct node
{
char name[30];
int age;
struct node *next;
} *list_head,*neos;
main()
{
}
void add_node_to_the_list(char data1[],int data2)
{
neos=(struct node *)malloc(sizeof(struct node));
strcpy(neos->name,data1);
age=data2;
neos->next=list_head;
list_head=neos;
}
void display_list()
{
struct node *p;
p=list_head;
while(p!=NULL)
{
puts(p->name);
printf("%d\n",age);
p=p->next;
}
}
When I compile this code I get an error because I haven't declare the "age" variable, although I have done that inside the struct node, outside the main function. Why?

Answer 1

Here you go:
#include <stdio.h>
#include <stdlib.h>
struct node
{
char name[30];
int age;
struct node *next;
}*list_head,*neos;
main()
{
}
void add_node_to_the_list(char data1[],int data2)/*Ç óõíáñôçóç áõôç ðñïóèåôåé êïìâï óôç ëéóôá*/
{
neos=(struct node *)malloc(sizeof(struct node));
strcpy(neos->name,data1);
neos->age=data2; //the correction is made here
neos->next=list_head;
list_head=neos;
}
void display_list()
{
struct node *p;
p=list_head;
while(p!=NULL)
{
puts(p->name);
printf("%d\n",p->age); //and here
p=p->next;
}
}
Note that you have been trying to access a struct element without pointing it.

Answer 2

Replace age=data2; by neos->age = data2;
and replace printf("%d\n",age); by printf("%d\n", p->age);
There is no age variable, age is a member of struct node.

Answer 3

You have declared it in a structure so to access it you have to pass by your structure
neos->age

Answer 4

age is just an element in a structure.
So assuming we have a structure defined as the following:
struct PlaceHolder {
int int_element
char char_element
} * place_holder;
to access any of the elements you need to access the structure first and reference the element in that structure.
place_holder->int_element = 5;
place_holder->char_element = "a";
In your case you have both list_head and neos as global variables, so to access an element in any of them you have to do:
list_head->age = data2;
neos->age = data2;