C Program to Search for an Element in Linked List

Here we’ll see how to write a C program to find an element in a linked list. The function is_present() takes a linked list (head pointer) and a value (val) as input arguments. If the value (val) is present in any of the nodes, this function returns the pointer of that node. Otherwise it returns NULL.

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

struct node{
    int val;
    struct node *next;
};

struct node *is_present(struct node *head, int val) {
    while(head) {
	  if(head->val == val) return head;
	  head = head->next;
	}
	
	return NULL;
}

void print_list(struct node *head)
{
    printf("H->");

    while(head)
    {
        printf("%d->", head->val);
        head = head->next;
    }

    printf("|||\n\n");
}

void insert_front(struct node **head, int value)
{
    struct node * new_node = NULL;

    new_node = (struct node *)malloc(sizeof(struct node));

    if (new_node == NULL)
    {
        printf("Failed to insert element. Out of memory");
    }

    new_node->val = value;
    new_node->next = *head;

    *head = new_node;
}

int main()
{
    struct node * head = NULL;
    
    /*Creating the linked list*/
    insert_front(&head, 16);
    insert_front(&head, 83);
    insert_front(&head, 89);
    insert_front(&head, 12);
    insert_front(&head, 67);
    insert_front(&head, 20);
    insert_front(&head, 2);
    
    
    printf("Linked List: ");
    print_list(head);
    
    printf("Finding 99 in the Linked List.\n");
    
    if(is_present(head, 99)) {
		printf("99 is present in the Linked List...\n");
	} else {
		printf("99 is not present in the Linked List.\n");
	}
	
	printf("\nFinding 12 in the Linked List...\n");
    
    if(is_present(head, 12)) {
		printf("12 is present in the Linked List.\n");
	} else {
		printf("12 is not present in the Linked List.\n");
	}
    
    return 0;
}

Here is the output of this program.