Question

Examine the following declarations and definitions for the array-based implementations for the Stack and Queue ADTs. Assume that exception class PushOnFullStack and class PopOnEmptyStack have been defined and are available. Read the following code segment and fill in blank #6.
class StackType
{

public:

StackType();

void Push(StackItemType item);

void Pop();

private:

int top;

ItemType items[MAX_STACK];

};

void StackType::StackType()

{

top = -1;

}

void StackType::Push(ItemType item)

{

__________________ // 1

___________________; // 2

__________________; // 3

___________________; // 4

}

class QueType

{

public:

// prototypes of QueType operations

// go here

private:

int front;

int rear;

ItemType items[MAX_QUEUE];

}

void QueType::QueType()

{

front = MAX_QUEUE - 1;

rear = MAX_QUEUE - 1;

}

Boolean QueType::IsEmpty()

{

return (rear == front);

}

void QueType::Enqueue(ItemType item)

{

____________________; // 5

____________________; // 6

}

[1] rear = (rear +1) % MAX_QUEUE
[2] items[rear] = item
[3] rear = (rear % MAX_QUEUE) + 1
[4] items[front] = item

Answer 1

Answer:

The codes for the respective blanks are given below with appropriate comments for better understanding

Explanation:

FOR 1 TO 4

Void StackType::Push(ItemType item)

{

if(top == MAX_STACK - 1) // means stack is full so we need to throw the PushOnFullStack exception

throw PushOnFullStack ; // You can use this class and appropriate method to deal with exception like printing that stack is full so can not push the current item

top ++ ;// increment the top to accumulate the next item

items[top] = item; // put the item into the place identified

}

FOR 5 AND 6

Void Quetype::enqueue(itemType item)

{

if (rear==MAX_QUEUE && front==0) // queue is full so can not enqueue

//Handle the queue full exception here, may be print this

}else

{

items[rear] = item;

rear ++;

}