Question

#include<stdio.h>
#include<malloc.h>

typedef struct node_t {
    int i;
    struct node_t* link;
} node;

node* head = NULL;

int main() {
    int i = 10;
    node* temp = NULL;
    head = (node *)malloc(sizeof(node));
    temp = (node *)malloc(sizeof(node));
    if(temp == NULL) {
        printf("\n malloc for temp node failed! \n");
    }
    else {
        /* linked list logic to add the elements in the beginning */
        while(i<=10) {
            temp->i = i;
            temp->link = NULL;
            if(head == NULL) {
                head = temp;
            }
            else {
                temp->link = head;
                head = temp;
            }
            i++;
        }
    }
    for(temp = head; temp->link != NULL; temp = temp->link) {
        printf("\n The data is:%d \n",temp->i);
    }
    free(temp);
    free(head);
    return 0;
}

I’m trying a simple linked list program. I’m not getting the output.

Answer 1

1) You have to allocate node (tmp) each time you are assigning value to tmp. and not allocate only one time the tmp. See the following fixed code to see how to do it

2) the following for loop is wrong:

for(temp = head; temp->link != NULL; temp = temp->link) {

This for loop is fixed in the following code

3) for the free you have to browse the whole linked list and then free each node. see the following fixed code.

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

typedef struct node_t{
    int i;
     struct node_t* link;
}node;

node* head = NULL;

int main(){
     int i = 1;
     node* temp = NULL;

     /* linked list logic to add the elements in the beginning */
     while(i<=10){
         temp = (node *)malloc(sizeof(node));
         if(temp == NULL){
             printf("\n malloc for temp node failed! \n");
             exit(1);
         }
         temp->i = i;
         temp->link = NULL;
         if(head == NULL){
             head = temp;
         }
         else{
             temp->link = head;
             head = temp;
         }
         i++;
     }

     for(temp = head; temp != NULL; temp = temp->link){
         printf("\n The data is:%d \n",temp->i);
     }

     while (head!=NULL)
     {
        temp = head->link;
        free(head);
        head = temp;
     }

}