Queue 1 : Array Implementation

Queue 1 : Array Implementation

Consider implementing a fixed size queue of maximum size 5 using an array.

Create a structure

struct queue {
int contents[5];
int front;
int count;
} ;

Note that the array contents holds the contents of the queue and the integer front stores the index of the front element in the queue.

Write a program to implement enQueue and deQueue operation on queue and to display the contents of the queue.

In the initQueue function intialize the value of front and count to 0.
Print the message “Queue is full” in the enQueue function when an attempt is made to insert a data into a full queue.
Print the message “Queue is empty” in the deQueue function and return the value -1000 when an attempt is made to delete data from an empty queue.

Refer function specifications for further details.

Input and Output Format:
Refer sample input and output for formatting specifications.

Note that the statement “The contents of the queue are” is in the main function. In the display function, if the queue is empty, print “ {}”.

[All text in bold corresponds to input and the rest corresponds to output]
Sample Input and Output:

Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
3
The contents of the queue are {}
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
10
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
20
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
30
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
40
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
50
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
60
Queue is full
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 10
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 20
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
1
Enter the element to be inserted/entered
60
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
3
The contents of the queue are 30 40 50 60
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 30
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 40
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 50
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
3
The contents of the queue are 60
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
The deleted element is 60
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
2
Queue is empty
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
3
The contents of the queue are {}
Choice 1 : Enter element into Queue
Choice 2 : Delete element from Queue
Choice 3 : Display
Any other choice : Exit
Enter your choice
4



Function Definitions:

void initQueue (struct queue * q)
void enQueue (struct queue * q, int element)
int deQueue (struct queue * p)
void display (struct queue q)



Code :
#include<stdio.h>
#include<string.h>
struct queue {
  int contents[5];
  int front;
  int count;
} ;

void initQueue(struct queue * q);
void enQueue(struct queue * q, int element);
int deQueue(struct queue * q);
void display( struct queue q);
void printMenu();

int main()
{
struct queue p;
int data,ch, data1;
initQueue(&p);
do {
printMenu();
printf("Enter your choice\n");
scanf("%d",&ch);
switch(ch) {
 case 1:
printf("Enter the element to be inserted/entered\n");
scanf("%d",&data);
enQueue(&p, data);
break;
 case 2:
data1 = deQueue(&p);
if(data1 != -1000)
printf("The deleted element is %d\n",data1);
break;
 case 3:
printf("The contents of the queue are");
display(p);
printf("\n");
break;
 default:
return 0;
}
} while(1);
return 0;
}


void printMenu()
{
printf("Choice 1 : Enter element into Queue\n");
printf("Choice 2 : Delete element from Queue\n");
printf("Choice 3 : Display\n");
printf("Any other choice : Exit\n");
}

void initQueue(struct queue * q)
{
    q->front=0;
    q->count=0;
}

void enQueue(struct queue * q, int element)
{
    int index;
    index=(q->count+q->front)%5;
    if(index==q->front&&q->count!=0)
    printf("Queue is full\n");
    else
    {
        q->count++;
        q->contents[index]=element;
    }
}

int deQueue(struct queue * q)
{
    int elem;
    if(q->count==0)
    {
        printf("Queue is empty\n");
        return (-1000);
    }
    elem=q->contents[q->front];
    q->count--;
    q->front=(q->front+1)%5;
    return elem;
}

void display( struct queue q)
{
    int i,index;
    if(q.count==0)
    printf(" {}");
    else
    {
        for(index=q.front,i=1;i<=q.count;i++,index++)
        printf(" %d",q.contents[index%5]);
    }
}