generic_linked_list.c

/*
 * Date: 2018-09-26
 *
 * Description:
 * Program to implement a linked list which can store any data.
 *
 * Approach:
 * Size of datatype is passed to push() and handled with that size while
 * inserting and printing elements of data.
 *
 * Complexity:
 * NA
 */

#include "stdio.h"
#include "stdlib.h"

typedef struct node {
  void *data;
  struct node *next;
} node;

void printInt(void *data) {
  printf("%d ",*(int *)data);
}

void printFloat(void *data) {
  printf("%f ",*(float *)data);
}

void printList(node *start, void (*fp)(void *)) {
  while (NULL != start) {
    fp(start->data);
    start = start->next;
  }
}

void push(node **head, void *data, int size) {
  int i = 0;
  node *tmp = (node *)malloc(sizeof(node));
  tmp->data = malloc(size);
  tmp->next = (*head);
  for (i = 0; i < size; i++) {
    *(char *)(tmp->data + i) = *(char *)(data + i);
  }
  (*head) = tmp;
}

int main(void) {
  node *start = NULL;
  int arr[] = {10, 5, 3, 20, 25};
  int i = 0;
  for (i = 0; i < 5; i++)
    push(&start, &arr[i], sizeof(int));

  printf("\nCreated linked list for int: ");
  printList(start, printInt);

  start = NULL;
  float fl[] = {1.2, 3.4, 3.3, 7.0, 5.0};
  for (i = 0; i < 5; i++)
    push(&start, &fl[i], sizeof(float));

  printf("\n\nCreated linked list for float: ");
  printList(start, printFloat);
  printf("\n\n");
  return 0;
}

/*
 * Output:
 * -----------------
 * Created linked list for int: 25 20 3 5 10
 *
 * Created linked list for float: 5.000000 7.000000 3.300000 3.400000 1.20000
 */