Exercises 3.3 E7

E7 Rewrite the methods for queue processing from the text ,using a flag to indicate a full queue instead of keeping a count of the entries in the queue

The class definition for this Queue implementation is as follows.

const int maxqueue=10; //small value for testing

class Queue {

Public:

Queue();

bool empty()const;

Error_code serve();

Error_code append(const Queue_entry &item);

Error_code retrieve(Queue_entry &item) const;

Protected;

int front,rear;

Queue_entry entry[maxqueue];

Bool is_empty;

}

The method implementations follow

Queue::Queue()

{

Rear=-1;

Front=0;

Is_empty=true;

}

bool Queue::empty()const

{

return is_empty;

}

Error_code Queue::append(const Queue_entry&item)

{

if {!empty()&&(rear+1)%maxqueue==front}return overflow;

is_empty=false;

rear =((rear+1)==maxqueue)?0:(rear+);

entry[rear]=item;

return success;

}

Error_code Queue::serve()

{

if(empty())return undeflow;

if(rear==front)is_empty=true;

front=((front+1)==maxqueue)?0:(front+1);

return success;

}

Error_code Queue::retrieve(Queue_entry&item)const

{

if(empty())return undflow;

Item=entry[front];

return success

}