So far we have seen array implementation of stack, stack using linear linked list. Today we will see stack using doubly linked list. Create stack, then push items in it and pop items from it.
# include< stdio.h >
# include< stdlib.h>
struct link
{
int info;
struct link *next;
struct link *prev;
};
void display(struct link *rec)
{
while(rec != NULL)
{
printf(" %d ",rec->info);
rec = rec->next;
}
}
struct link * push(struct link *rec)
{
struct link *new1;
printf("\n Enter value for stack:-");
new1 = (struct link *)malloc(sizeof(struct link));
scanf("%d", &new1->info);
new1->next = rec;
/* next pointer of new1 is holding the address of the first node of the list. so new1 is the first node now.*/
rec->prev=new1;
rec = new1;
/* from this point the pointer rec is pointing the first node of the list. */
return rec;
}
struct link * pop(struct link *rec)
{
struct link *temp;
if(rec == NULL)
{
printf("\n Stack is empty");
}
else
{
/*rec is pointing the first node of the list. */
temp = rec->next;
/* temp is pointing the second node of the list.*/
rec->next->prev=temp;
free(rec);
rec = temp;
printf("\n After pop operation the stack is as follows:\n");
display(rec);
if(rec == NULL)
printf("\n Stack is empty");
}
return rec;
}
int selection()
{
int choice;
do
{
printf("\n 1<-Push ");
printf("\n 2<-Pop");
printf("\n 3<-Quit");
printf("\n Input your choice :");
scanf("%d", &choice);
if(choice <1 || choice >3)
printf("\n Incorrect choice-> Try once again");
} while(choice <1 || choice >3);
return choice;
}
void main()
{
struct link *start ;
int choice;
clrscr();
start = NULL;
do
{
choice = selection();
switch(choice)
{
case 1:
start = push(start);
printf("\n After push operation stack is as follows:\n");
display(start);
break;
case 2:
start = pop(start);
break;
default :
printf("\n End of session");
}
} while(choice != 3);
getch();
}
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