I created a linked list function which return a pointer to the node. Then I iterated n amount times to accept the number from the user and store it in a linked list, connecting all the nodes. But it is only printing the first and last node. See my code below:

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

typedef struct node {
    int number;
    struct node *next;
} nd;

nd* create(int num);

int main(void) {
    int n;
    printf("How many numbers do you intend on entering ");
    scanf("%d", &n);
    int num;
    nd* bg = NULL;

    for (int i = 0; i < n; i  ) {
        printf("Enter a number");
        scanf("%d", &num);
        nd *ls = malloc(sizeof(nd));
        ls = create(num);
    
        if (i == 0) {
            bg = ls;
        }
        else {
            nd *p = malloc(sizeof(nd));
            p = bg;
            p->next = ls;
        }
    }

    for (nd *k = bg; k != NULL; k = k->next) {
        printf("%d\n", k->number);
    }
}

nd* create(int num) {
    nd *list = malloc(sizeof(nd));

    if (list == NULL) { // Check to if we have ran out of memory
        return 0;
    }

    list->number = num;
    list->next = NULL;

    return list;
}

CodePudding user response：

First thing I notice: create allocates memory for a new node. So why allocate memory before that for the same pointer?

        nd *ls = malloc(sizeof(nd));
        ls = create(num);

The results of this first malloc, if it succeeded, are now unable to be freed as we do not have a pointer to it.

Within your loop, you have created a node ls and then another p.

Slow down and think through what you're doing. In your loop:

• You prompt for a number.
• Create a node with that data.
• If your head node bg is NULL you have bg point to that node.
• Otherwise you link that node to the previous node.

int main(void) {
    int n;
    printf("How many numbers do you intend on entering ");
    scanf("%d",&n);

    int num;
    nd *bg = NULL;
    nd *cur, *prev;

    for (int i = 0; i < n; i  ) {
        printf("Enter a number");
        scanf("%d",&num);
        cur = create(num);

        if (!bg) {
            bg = cur;
        }
        else {
            prev->next = cur;
        }

        prev = cur;
    }

    for (nd *k = bg; k != NULL; k = k->next) {
       printf("%d\n",k->number);
    }

    return 0;
}

You'll also want to walk your list and free all of the memory you've allocated.