Answer to Question #256365 in C for Amit

Question

Write a C code to delete all prime numbers present in a doubly linked list. For example, if

input: 5->6->11->4->12->16, then output 6->4->12->16.

Answer 1

#include <stdio.h>
 


 #include <stdbool.h>


struct doubleLinkedList {
    int data;
    struct doubleLinkedList *prev, *next;
};
 


void add(struct doubleLinkedList** head, int data)
{
    
    struct doubleLinkedList* node = (struct doubleLinkedList*)malloc(sizeof(struct doubleLinkedList));
 
    
    node->data = data;
 
    
    
    node->prev = NULL;
 
    
    node->next = (*head);
 
    
    if ((*head) != NULL)
        (*head)->prev =node;
 
    
    (*head) = node;
}
 


bool isPrime(int x)
{
    int  i;
    if (x <= 1)
        return false;
    if (x <= 3)
        return true;
 
   
    if (x % 2 == 0 || x % 3 == 0)
        return false;
 
    for (i = 5; i * i <= x; i = i + 6)
        if (x % i == 0 || x % (i + 2) == 0)
            return false;
 
    return true;
}
 


void deleteItem(struct doubleLinkedList** head, struct doubleLinkedList* node)
{
  
    if (*head == NULL || node == NULL)
        return;
 
    
    if (*head == node)
        *head = node->next;
 
   
    if (node->next != NULL)
        node->next->prev = node->prev;
 
    
    if (node->prev != NULL)
        node->prev->next = node->next;
 
    
    free(node);
 
    return;
}
 


void deletePrimeNumbers(struct doubleLinkedList** head)
{
    struct doubleLinkedList* ptr = *head;
    struct doubleLinkedList* next;
 
    while (ptr != NULL) {
        next = ptr->next;
        
        if (isPrime(ptr->data))
            deleteItem(head, ptr);
        ptr = next;
    }
}
 


void display(struct doubleLinkedList* node)
{
    while (node != NULL) {
        printf("%d  ", node->data );
        node = node->next;
    }
}
 


int main()
{
     
    struct doubleLinkedList* node = NULL;
  
    add(&node, 16);
    add(&node, 12);
    add(&node, 4);
    add(&node, 11);
    add(&node, 6);
    add(&node, 5);
   printf("Before modifying the List:  \n");
    
    display(node);
 
    deletePrimeNumbers(&node);
   printf("\nAfter modified the List:\n ");
    
    display(node);
}