C program for Singly Linked list

Singly Linked Lists are a type of data structure. In a singly linked list, each node in the list stores the contents and a pointer or reference to the next node in the list. It does not store any pointer or reference to the previous node. To store a single linked list, only the reference or pointer to the first node in that list must be stored. The last node in a single linked list points to nothing.

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

//............................................Function Creation...........................................//

void createlinkedlist();
void display();
void insert_at_first();
void delete_from_first();
void delete_from_end();
void insert_at_selected_position();
void delete_entire_list();
void reverse_nodes();

//.........................................structure node...............................................//

struct node
{
    int roll;
    char name[30];
    struct node *next;
};
struct node *head;

//......................................................MAIN..............................................//

int main()
{

    int ch;
    do
    {

        printf("\n\n\n\n\n\n\t\t\t1.Create Linked list");
        printf("\n\t\t\t2.Display List");
        if(head!=NULL)
        {

            printf("\n\t\t\t3.Delete From First\t");
            printf("\n\t\t\t4.Delete From end\t");
            printf("\n\t\t\t5.Insert at first\t");
            printf("\n\t\t\t6.Insert at selected position");
            printf("\n\t\t\t7.Delete entire List");
            printf("\n\t\t\t8.Reverse List");
        }

        printf("\n\t\t\t9.Exit\t");


        scanf("%d",&ch);
        switch(ch)
        {
        case 1:
            createlinkedlist();
            break;
        case 2:
            display();
            break;
        case 9:
            exit (0);
            break;
        case 5:
            insert_at_first();
            break;
        case 3:
            delete_from_first();
            break;
        case 4:
            delete_from_end();
            break;
        case 6:
            insert_at_selected_position();
            break;
        case 7:
            delete_entire_list();
            break;
        case 8:
            reverse_list();
            break;
        default:
            printf("Wrong choice Try again......");
        }
    }while(ch!=3);

}

//............................................Create linked list.................................................//

void createlinkedlist()
{
    system("cls");
    struct node *newnode,*temp;
    newnode=(struct node*)malloc(sizeof(struct node));
    printf("\n\n\t\t\tRoll :  ");
    scanf("%d",&newnode->roll);
    printf("\t\t\tName :  ");
    scanf("%s",&newnode->name);
    newnode->next=NULL;
    if(head==NULL)
    {
        head=newnode;
    }
    else
    {
        temp=head;
        while(temp->next!=NULL)
        {
            temp=temp->next;
        }
        temp->next=newnode;
    }
}

// ......................................................DISPLAY............................................//

void display()
{
    system("cls");
    struct node *temp;
    printf("\n\n\t\t\tRoll\t\tName\n");
    if(head!=NULL)
    {
        for(temp=head;temp!=NULL;temp=temp->next)
            printf("\t\t\t%d\t\t%s\n",temp->roll,temp->name);


    }
    else
    {
        printf("\n\t\t\tList is empty Boss... %c %c ",2,2);
    }
}

//............................................Insert At FIrst.................................................//

void insert_at_first()
{
    system("cls");
    struct node *temp,*newnode;
    newnode=(struct student *)malloc(sizeof(struct node));
    printf("\n\n\t\t\tRoll :  ");
    scanf("%d",&newnode->roll);
    printf("\t\t\tName :  ");
    scanf("%s",&newnode->name);
    temp=head;
    head=newnode;
    newnode->next=temp;

    return 0;
}

//..............................................Delete from first.....................................................//

void delete_from_first()
{
    system("cls");
    struct node *temp;
    if(head==NULL)
    {
        printf("\n\t\t\tList is empty Boss... %c %c ",2,2);
    }
    else
    {
        temp=head;
        free(head);
        head=temp->next;
        printf("\n\n\t\t\tFirst list deleted from node...");
    }

    return 0;

}

//..............................................Delete from end................................................//

void delete_from_end()
{
    system("cls");
    struct node *temp,*newtemp;
    temp=head;

    while(temp->next!=NULL)
    {
        newtemp=temp;
        temp=temp->next;
        if(temp->next==NULL)
            newtemp->next=NULL;
    }
    free(temp);

    printf("\n\n\t\t\tLast node is deleted....");
    return 0;

}

//..................................................Insert at selected position....................................//

void insert_at_selected_position()
{
    struct node *temp;
    struct node *new_temp,*temp_copy;
    temp=head;
    int position,i;
    printf("\n\n\t\t\tEnter the roll before you want to insert\t");
    scanf("%d",&position);
    for(i=1;i<position;i++)
    {
        temp=temp->next;
    }
    temp_copy=temp->next;
    new_temp=(struct node *)malloc(sizeof(struct node));
    temp->next=new_temp;
    printf("\n\n\t\t\tRoll :  ");
    scanf("%d",&new_temp->roll);
    printf("\t\t\tName :  ");
    scanf("%s",&new_temp->name);
    new_temp->next=temp_copy;
    return 0;
}

//..................................................free entire list........................................//

void delete_entire_list()
{
    system("cls");
    struct node *temp,*had;
    temp=head;
    if(temp->next==NULL)
    {
        free(temp);
    }
    else
    {
    while(temp!=NULL)
    {
        had=temp;
        temp=temp->next;
        free(had);
    }
    }
    head=NULL;


    return 0;
}

//.......................................Reverse List....................................//

void reverse_list()
{
    system("cls");
    if(head->next==NULL)
    {
        printf("\n\n\tsorry BOSS %c reverse not possible...",1);
    }
    else
    {
    struct node *p1,*p2,*p3;
    p1=head;
    p2=p1->next;
    p3=p1->next->next;
    p1->next=NULL;


    while(p3!=NULL)
    {

        p2->next=p1;
        p1=p2;
        p2=p3;
        p3=p3->next;

    }
    p2->next=p1;
    head=p2;
    }

}