Singly linked list in c program with output

SINGLY LINKED LIST OPERATION

#include< stdio.h>

#include< conio.h>
#include< alloc.h>
void create();
void insert();
void delet();
void display();
struct  node
{
int data;
struct node *link;
};
struct node *first=NULL,*last=NULL,*next,*prev,*cur;
void create()
{
cur=(struct node*)malloc(sizeof(struct node));
printf("\nENTER THE DATA: ");
scanf("%d",&cur->data);
cur->link=NULL;
first=cur;
last=cur;
}
void insert()
{
int pos,c=1;
cur=(struct node*)malloc(sizeof(struct node));
printf("\nENTER THE DATA: ");
scanf("%d",&cur->data);
printf("\nENTER THE POSITION: ");
scanf("%d",&pos);
if((pos==1) &&(first!=NULL))
{
cur->link = first;
first=cur;
}
else
{
next=first;
while(c<pos)
{
prev=next;
next=prev->link;
c++;
}
if(prev==NULL)
{
printf("\nINVALID POSITION\n");
}
else
{
cur->link=prev->link;
prev->link=cur;
}
}
}
void delet()
{
int pos,c=1;
printf("\nENTER THE POSITION : ");
scanf("%d",&pos);
if(first==NULL)
{
printf("\nLIST IS EMPTY\n");
}
else if(pos==1 && first->link==NULL)
{
printf("\n DELETED ELEMENT IS %d\n",first->data);
free(first);
first=NULL;
}
else if(pos==1 && first->link!=NULL)
{
cur=first;
first=first->link;
cur->link=NULL;
printf("\n DELETED ELEMENT IS %d\n",cur->data);
free(cur);
}
else
{
next=first;
while(c<pos)
{
cur=next;
next=next->link;
c++;
}
cur->link=next->link;
next->link=NULL;
if(next==NULL)
{
printf("\nINVALID POSITION\n");
}
else
{
printf("\n DELETED ELEMENT IS %d\n",next->data);
free(next);
}
}
}
void display()
{
cur=first;
while(cur!=NULL)
{
printf("\n %d",cur->data);
cur=cur->link;
}
}
void main()
{
int ch;
clrscr();
printf("\n\nSINGLY LINKED LIST");
do
{
printf("\n\n1.CREATE\n2.INSERT\n3.DELETE\n4.EXIT");
printf("\n\nENTER YOUR CHOICE : ");
scanf("%d",&ch);
switch(ch)
{
case 1:
create();
display();
break;
case 2:
insert();
display();
break;
case 3:
delete();
display();
break;
case 4:
exit(0);
default:
printf("Invalid choice...");
}
}

while(1);

}

 

Output:

SINGLY LINKED LIST

1.CREATE

2.INSERT

3.DELETE

4.EXIT
 

ENTER YOUR CHOICE : 1

ENTER THE DATA: 3

                                    3

1.CREATE

2.INSERT

3.DELETE

4.EXIT

ENTER YOUR CHOICE : 2

ENTER THE DATA: 4

ENTER THE POSITION: 1

 4

 3

1.CREATE

2.INSERT

3.DELETE

4.EXIT

ENTER YOUR CHOICE : 2

ENTER THE DATA: 6

ENTER THE POSITION: 2

 4

 6

 3

1.CREATE

2.INSERT

3.DELETE

4.EXIT

ENTER YOUR CHOICE : 3

ENTER THE POSITION : 2

DELETED ELEMENT IS 6

 4

 3

1.CREATE

2.INSERT

3.DELETE

4.EXIT

ENTER YOUR CHOICE : 4