C Programs based on LInked List

Sample Program 1:
Simple linear linked list constructed in c.Adding 10 elements into the list and print them
Program

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

struct Node
{
   //each node contains a data and a pointer to the next node in the list
   int data;
   struct Node *next;
};

typedef struct Node node;

int main()
{
    node *newnode,*head,*first;
    int i;
    head=NULL;
    first=NULL;

    //Inserting 10 nodes in a list
    for(i=1;i<=10;i++)
    {
       newnode=(node*)malloc(sizeof(node));
       newnode->data=i;
       newnode->next=NULL;
  
       if(head==NULL)
       {
          head=newnode;
          first=newnode; //To point the first node in the list
        }
        head->next=newnode;
        head=newnode;
    }
     //Print the nodes in the list
     newnode=first;
     while(newnode)
     {
          printf("%d\t",newnode->data);
          newnode=newnode->next;
     }
}


Output:
1 2 3 4 5 6 7 8 9 10


Sample Program 2
Write a C program to perform the basic operation like insertion,deletion,display in a singly linked list.
solution
#include<stdio.h>
#include<stdlib.h>

void Insert_list(int);
void Insert_pos(int,int);
void delete_list(int);
void display(void);
void search(int);

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

typedef struct Node node;
node *head=NULL,*curr=NULL;

int main()
{
    int ch,n,m;
    do
    {
        printf("ENter your choice\n1.Insert end of list\n2.Insert at position\n3.Delete\n4.Search\n5.Display\n6.Exit\n");
        scanf("%d",&ch);
        switch(ch)
        {
            case 1:
                    printf("Enter the data to insert\n");
                    scanf("%d",&n);
                    Insert_list(n);
                    break;
            case 2:
                    printf("Enter the data to insert\n");
                    scanf("%d",&n);
                    printf("Enter the position after the data is insert\n");
                    scanf("%d",&m);
                    Insert_pos(n,m);
                    break;
            case 3:
                    printf("Enter the data item to be delete\n");
                    scanf("%d",&n);
                    delete_list(n);
                    break;
            case 4:
                    printf("Enter the data item to be search\n");
                    scanf("%d",&n);
                    search(n);
                    break;
            case 5:
                    display();
                    break;
            case 6:
                    exit(0);
            default:
                    printf("Enter a valid digit\n");
                    break;
        }
    }while(ch>=1 && ch<=6);
}
void Insert_list(int n)
{
    node *newnode;
    //creating a new node with data n
    newnode=(node *)malloc(sizeof(node));
    newnode->data=n;
    newnode->next=NULL;
    //check the head node. If head is NULL then the list is empty
    //insert this node as the head node
    if(head==NULL)
    {
        head=newnode;
        curr=head;
    }
    else
    {
        //curr is the pointer pointing the last node of the list
        curr->next=newnode;
        curr=newnode;
    }
}

void Insert_pos(int n,int pos)
{
    node *nnode,*newnode;
    int i;
    if(head==NULL)
    {
        printf("The list is empty\n");
        return;
    }
    //assigning a temporary pointer nnode to point the head node
    nnode=head;
    //finding the position in the list
    for(i=0;i<pos-1;i++)
    {
        nnode=nnode->next;
        if(nnode==NULL) //reached end of list
        {
            printf("There are less than %d nodes in the list\n",pos);
            return;
        }
    }
    //found the position to insert
    //create a newnode with given data n
    newnode=(node *)malloc(sizeof(node));
    newnode->data=n;
    newnode->next=NULL;
    //inserting after the position
    newnode->next=nnode->next;
    nnode->next=newnode;
    printf("Node with value %d inserted after %d position\n",n,pos);
    return;
}

void delete_list(int n)
{
//Search the given item in the list if it is present delete or print a message
    node *nnode,*temp;
    if(head==NULL)
    {
        printf("The List is Empty\n");
        return;
    }
    //If the data is present in the first node
    if(head->data==n)
    {
        temp=head;
        head=head->next;
        free(temp);
        return;
    }
    nnode=head;

    while(nnode->next->next!=NULL)
    {
        if(nnode->next->data==n)
        {
            temp=nnode->next;
            nnode->next=temp->next;
            free(temp);
            printf("node with value %d is deleted\n",n);
            return;
        }
        else
        {
            nnode=nnode->next;
        }
    }
    //Deleting the last node
    if(nnode->next->data==n)
    {
        temp=nnode->next;
        nnode->next=NULL;
        free(temp);
        printf("The node with value %d is deleted\n",n);
        return;
    }
    //Reached end of list and the item is not present
    printf("The node with value %d is not found\n",n);
    return;
}

void search(int n)
{
    node *nnode;
    nnode=head;
    while(nnode)
    {
        if(nnode->data==n)
        {
            printf("Node with data %d found\n",n);
            return;
        }
        nnode=nnode->next;
    }
    printf("Node with data %d is not found\n",n);
}

void display()
{
    node *nnode;
    if(head==NULL)
    {
        printf("Empty list\n");
        return;
    }
    nnode=head;
    while(nnode)
    {
        printf("%d->",nnode->data);
        nnode=nnode->next;
    }
}

Exercise Programs in Linked list

1. Modify sample program 1 to store items in the reverse order. ie while printing the list the output should be 10 9 8 7 6 5 4 3 2 1.