Insertion in Linklist:- The Insertion of Element in Singly linklist at different places like: insertion at beginning, last and middle in the linklist. In below code I will show you how to insert the element in linklist at beginning, middle and last.

insert_beg():- This function insert an Element at beginning in the linklist and move the pointer start to the newly inserted node.

insert_end():- This function insert an Element at Last in the linklist and move the end pointer to the newly inserted nodes.

insert_mid():- This function insert an Element at middle in the linklist for that have taken two pointers temp and p initially both will point at the start pointer and after first iteration the p pointer will point to the next element and temp pointer will point one element behind where the p pointer will points.

See the code example below-

#include<stdio.h>
#include<conio.h>
#include<malloc.h>
#include<process.h>

struct node
{
int info;
struct node *next;
};
typedef struct node NODE;

NODE *node=NULL,*start=NULL,*end=NULL;

void create();
void insert_beg();
void insert_end();
void insert_mid();
void disp();

void main()
{
int ch;
clrscr();
    while(1)
    {

        printf("\n1:Create Linklist");
        printf("\n2:Insert Element At Begining");
        printf("\n3:Insert Element At Middle");
        printf("\n4:Insert Element At Last");
        printf("\n5:Display");
        printf("\n6:Exit");
        printf("\n\tEnter Your Choice:-");
        scanf("%d",&ch);

        switch(ch)
        {
            case 1:
            create();
            break;

            case 2:
            insert_beg();
            break;

            case 3:
            insert_mid();
            break;

            case 4:
            insert_end();
            break;

            case 5:
            disp();
            break;

            case 6:
            exit(1);

            default:
            printf("\n\tOption Not Available");
            break;

        }
    }
getch();
}

void create()
{
    node=(NODE *)malloc(sizeof(NODE));
    printf("\n\tEnter the Element:-");
    scanf("%d",&node->info);
    node->next=NULL;

    if(start==NULL)
    {
      start=node;
      end=node;
    }
    else
    {
      end->next=node;
      end=node;
    }
}

void disp()
{
NODE *temp;
temp=start;


    if(start==NULL)
    {
        printf("\n\tNo Element to Display Please Insert Element First");
    }
    else
    {
        while(temp!=NULL)
        {
            printf("%d\n",temp->info);
            temp=temp->next;
        }
    }

}

void insert_beg()
{
    node=(NODE *)malloc(sizeof(NODE));
    printf("\n\tEnter the Element:-");
    scanf("%d",&node->info);

    node->next=start;
    start=node;

}

void insert_end()
{
    node=(NODE *)malloc(sizeof(NODE));
    printf("\n\tEnter the Element:-");
    scanf("%d",&node->info);

    node->next=NULL;
    end->next=node;
    end=node;

}

void insert_mid()
{
int flag=0,no=0;
NODE *temp,*p;
temp=p=start;



    node=(NODE *)malloc(sizeof(NODE));
    printf("\n\tEnter the Element You Want to Insert:-");
    scanf("%d",&node->info);

    printf("\n\tInsert After Which Element in Linklist:=");
    scanf("%d",&no);

    while(p!=NULL)
    {
       if(p->info==no)
       {
        flag=1;
           node->next=p->next;
           p->next=node;
           break;
       }
       else
       {
        temp=p;
        p=p->next;
       }
    }
    if(flag==0)
    printf("\n\tElement You Want to Insert After is Not Present in Linklist");



}