Single Linked List using C

Here is a single linked list data structure using C Language:


#include

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

struct node *first = NULL;

int menu();

struct node * insert_node(int data);
struct node * delete_node(int data);
int count_node(struct node *);
int traverse_list(struct node *);


int menu()
{
int item = 0;

return item;
}

/*
* This routine will insert a new node to the left hand side of a linked list. And make this new node as the first node after insertion.
*/
struct node * insert_node(int data)
{
        struct node * temp = NULL;

        temp = (struct node *)malloc(sizeof(struct node));
        if (!temp)
                printf("Not enough memory in the system\n");

        // insert data;
        temp->data = data;

        if(first == NULL)
        {
                first = temp;
                temp->next = NULL;
                //printf("data=%d\n", temp->data);
        }
        else
        {
                temp->next = first;
                first = temp;
        }

return first;
}
/*
delete_node(int data) deletes the first node from the singly linked list where the data matches, and returns the starting of the list.
*/
struct node * delete_node(int data)
{
struct node * current = first, *prev;
//search the list for the first occurance of "data". If no node with "data" found then the list remains the same.

        while(current && current->data!=data)

        {

                prev = current;

                current=current->next;

        }

        prev->next = current->next;

        free(current);

return first;

}

int traverse_list(struct node *list_head)

{

        struct node * current, *prev;

        if (!first)

                printf("Empty list\n");

        current = first;

        prev = current->next;

        printf("\n\nList = ");

#if 1

        while(current)

        {

                printf("\t %d", current->data);

                current = current->next;

        }

#endif

        printf("\n\n");

}

main()

{

insert_node(30);

insert_node(40);

insert_node(50);

insert_node(60);

insert_node(70);

traverse_list(first);

delete_node(50);

traverse_list(first);

return 0;

}

Result of running this program:

kongkon@Linkat-Luidia:~/sea> ./a.out

List =   70      60      50      40      30

List =   70      60      40      30