Thread: Linked list and nodes

Hi i am writing this piece of code which takes 3 field , store it into struct, but i dont know how to create the node and the function print_planet_list() should walk through the linked list and print out the outputs.

Code:

    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>


    /* the struct */
    typedef struct{
      char name[128];
      double dist;
      char description[1024];
    } planet_t;
    
    /* have to write a definition here */
    typedef struct planet_node {
      ???;              /* what to write here? */
    } planet_node;
    
    /* Print a list of planets pointed to by ptr */
    void print_planet_list(planet_node *ptr){
      while(ptr != NULL){
        printf("%15s %10.2f %s\n",
            new[i].name,
            new[i].dist,
            new[i].description);/* not sure if its correct */
      }
      printf("\n");
    }
    
    int main(){
      char buf[64];
      planet_node *head = NULL;
      int quit = 0;
      
      do {
        printf("Enter planet name (q quits): ");
        scanf("%s",buf);
        if((strcmp(buf,"q")==0)){
          quit = 1;
        }
        else{
          planet_node *new = (planet_t *) malloc(sizeof(planet_t)*? );      //how do i declare ?  
          strcpy(???);            
          printf("Enter distance and description: ");
          scanf(" %lf ", new[i].dist); 
          gets(new[i].description);       
          ptr->head;           /* Link new node to head */
          ???;           /* Set the head to the new node */
        }
      } while(!quit);
    
      printf("Final list of planets:\n");
      print_planet_list(head);
      
     
      while(head != NULL){
        planet_node *remove = head;
        head = (*head).next;
        free(remove);
           }
        }

my desired input is :
Enter planet name (q quits): Earth
Enter distance and description: 0.9 Friendly and hospitable
Enter planet name (q quits): Mars
Enter distance and description: 1.05 Very cosmopolitan


output:


Mars 1.05 Very cosmopolitan
Earth 0.90 Friendly and hospitable

Do you know how linked lists work?
If not, I suggest reading through these two links from this site:
Linked Lists in C Tutorial - Cprogramming.com
FAQ > Linked List Issues - Cprogramming.com

Code:

/* have to write a definition here */
typedef struct planet_node {
     ???;              /* what to write here? */
} planet_node;

When you read the two links above you will learn that a node consist of a data element and a pointer to the next node. What's the data element in your case?

Code:

planet_node *new = (planet_t *) malloc(sizeof(planet_t)*? );      //how do i declare ?

Read FAQ > Casting malloc - Cprogramming.com to learn how to use malloc() in C (especially the last part about the method most experienced programmers use).

Bye, Andreas

well it just suffices for you to create a structure with three fields and a pointer to the next node as in:

Code:

typedef struct {
    int field1, field 2, field3;
     struct node *next;
}planet_node;

and you can access the members using pointers as in

Code:

planet_node->field1 = "any user input of your choice"

can this help you proceed??