Description:
In this program we have to implement the Queue operation by using the pointers. Here they Queue operation are push and pop. Push operation is used to insert the elements into a Queue and pop operation is used to remove the elements in to a Queue.
Algorithm:
Step 1: Start
Step 2: define structure for queue
Step 3: read choice
Step 4: if choice = insert
i) read the element
ii) create a data structure
iii) if empty queue then front of queue pinter points to newly created data structure
iv) otherwise end of the queue points to newly created data structure
Step 5: if choice= remove
i) check if queue is empty . if so, print queue is empty
ii) otherwise read the element pointed by front of the queue temp pointer points to front of queue
iii) front of queue points to next element
iv) free the element pointed by temp pointer
v) return the element
vi) print the element
Step 6: if choice = display
i) check of empty queue if so, print queue empty
ii) otherwise print the elements from front of the queue until the end of the queue
step 7: if choice=exits stop
program:
#define true 1
#define false 0
#include<stdio.h>
#include<conio.h>
#include<process.h>
struct q_point
{
int ele;
struct q_point* n;
};
struct q_point *f_ptr = NULL;
int e_que(void);
void add_ele(int);
int rem_ele(void);
void show_ele();
/*main function*/
void main()
{
int ele,choice,j;
while(1)
{
clrscr();
printf("\n\n****IMPLEMENTATION OF QUEUE USING POINTERS****\n");
printf("==============================================");
printf("\n\t\t MENU\n");
printf("==============================================");
printf("\n\t[1] To insert an element");
printf("\n\t[2] To remove an element");
printf("\n\t[3] To display all the elements");
printf("\n\t[4] Exit");
printf("\n\n\tEnter your choice:");
scanf("%d", &choice);
switch(choice)
{
case 1:
{
printf("\n\tElement to be inserted:");
scanf("%d",&ele);
add_ele(ele);
getch();
break;
}
case 2:
{
if(!e_que())
{
j=rem_ele();
printf("\n\t%d is removed from the queue",j);
getch();
}
else
{
printf("\n\tQueue is Empty.");
getch();
}
break;
}
case 3:
show_ele();
getch();
break;
case 4:
exit(1);
break;
default:
printf("\n\tInvalid choice.");
getch();
break;
}
}
}
/* Function to check if the queue is empty*/
int e_que(void)
{
if(f_ptr==NULL)
return true;
return false;
}
/* Function to add an element to the queue*/
void add_ele(int ele)
{
struct q_point *queue = (struct q_point*)malloc(sizeof(struct q_point));
queue->ele = ele;
queue->n = NULL;
if(f_ptr==NULL)
f_ptr = queue;
else
{
struct q_point* ptr;
ptr = f_ptr;
for(ptr=f_ptr ;ptr->n!=NULL; ptr=ptr->n);
ptr->n = queue;
}
}
/* Function to remove an element from the queue*/
int rem_ele()
{
struct q_point* queue=NULL;
if(e_que()==false)
{
int j = f_ptr->ele;
queue=f_ptr;
f_ptr = f_ptr->n;
free (queue);
return j;
}
else
{
printf("\n\tQueue is empty.");
return -9999;
}
}
/* Function to display the queue*/
void show_ele()
{
struct q_point *ptr=NULL;
ptr=f_ptr;
if(e_que())
{
printf("\n\tQUEUE is Empty.");
return;
}
else
{
printf("\n\tElements present in Queue are:\n\t");
while(ptr!=NULL)
{
printf("%d\t",ptr->ele);
ptr=ptr->n;
}
}
}
Output:
****IMPLEMENTATION OF QUEUE USING POINTERS****
==============================================
MENU
==============================================
[1] To insert an element
[2] To remove an element
[3] To display all the elements
[4] Exit
Enter your choice:1
Element to be inserted:23
****IMPLEMENTATION OF QUEUE USING POINTERS****
==============================================
MENU
==============================================
[1] To insert an element
[2] To remove an element
[3] To display all the elements
[4] Exit
Enter your choice:
3
Elements present in Queue are:
23
****IMPLEMENTATION OF QUEUE USING POINTERS****
==============================================
MENU
==============================================
[1] To insert an element
[2] To remove an element
[3] To display all the elements
[4] Exit
Enter your choice:2
23 is removed from the queue
****IMPLEMENTATION OF QUEUE USING POINTERS****
==============================================
MENU
==============================================
[1] To insert an element
[2] To remove an element
[3] To display all the elements
[4] Exit
Enter your choice:4
Exit
Conclusion : the program is error free
VIVA QUESATIONS:
1) Define queue ?
Ans: A queue is a linear, sequential list of that are accessed in the oeder first in first out(FIFO).
2) Define circular queues ?
Ans: A queue can also be circular in which case, it is called as a circular queue
3) What are the various stack oriented notations ?
Ans: i) infix ii) prefix iii) postfix
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