Self referential structure (Notation of linklist ) / Singly link list in C

Self referential structure (Notation of linklist ) / Singly link list in C. A link list is a data structure that maintain the list of items that are logically connected with links (pointer). Link list is of four types:-

Self referential structure (Notation of linklist ) / Singly link list in C:-

/* Implementation of singly link list  */                                                                         

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

// define structure of a node

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

struct node *start=NULL;

// create a node

struct node * create_node()
{
     struct node *temp;
     temp=(struct node*)malloc(sizeof(struct node));
     return temp;
}

// function for insert element at first position

void insert_first()
{
    struct node *temp;
    temp=create_node();
    printf("Enter a element\n");
    scanf("%d",&temp->data);
    temp->link=start;
    start=temp;
}
 
 // function for insert element at the end of the list
 
void insert_end()
{
    struct node *temp,*t;
    temp=create_node();
    printf("Enter a element\n");
    scanf("%d",&temp->data);
    if(start==NULL)
    {
        temp->link=start;
        start=temp;
    }
    else
    {
        t=start;
        temp->link=NULL;
        while(t->link!=NULL)
          t=t->link;
        t->link=temp;
    }
}

// function for delete element from the starting

void delte_first()
{
    struct node * temp;
    if(start==NULL)
      printf("List is empty\n");
    else
    {
        temp=start;
        start=temp->link;
        free(temp);
    }
}

// function for delete element from the end of the list

void delete_end()
{
    struct node * temp,*t;
    if(start==NULL)
    {
        printf("List is empty\n");
    }
    else
    {
        t=start;
        if(t->link==NULL)
        {
         start=NULL;
         free(t);
        }
        else
        {
         while(t->link->link!=NULL)
         {
            t=t->link;
         }
         temp=t->link;
         t->link=NULL;
        free(temp);
        }
    }
}

// function for display the element of List

void display()
{
    struct node * temp;
    if(start==NULL)
      printf("List is empty\n");
    else
    {
        temp=start;
        while(temp!=NULL)
        {
            printf("%d ",temp->data);
            temp=temp->link;
        }
    }
}
int main()
{
    int ch;
    printf("1. insert element at starting\n");
    printf("2. insert element at the end of the list\n");
    printf("3. delete element from the starting\n");
    printf("4. delete element from the end of the list\n");
    printf("5. display element of the list\n");
    printf("6. exit\n");
    while(1)
    {
        printf("Enter your choice\n");
        scanf("%d",&ch);
        switch(ch)
        {
            case 1: insert_first();
                    break;
            case 2: insert_end();
                    break;
            case 3: delte_first();
                    break;
            case 4: delete_end();
                    break;
            case 5: display();
                    break;
            case 6: exit(0);
            default: printf("Wrong key\n");
        }
    }
    return 0;
}