Stack Implementation in C++: Class Definition and Operations, Slides of Data Structures and Algorithms

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Chapter 5

ADTs Stack and Queue

Lecture 11

Stacks of Coins and Bills

Definition of Stack

• Logical (or ADT) level: A stack is an

ordered group of homogeneous items

(elements),

• in which the removal and addition of

stack items can take place only at the

top of the stack.

• A stack is a LIFO “last in, first out”

structure.

Stack ADT Operations

• MakeEmpty -- Sets stack to an empty state.
• IsEmpty -- Determines whether the stack is currently

empty.

• IsFull -- Determines whether the stack is currently full.
• Push (ItemType newItem) -- Throws exception if stack is full; otherwise adds newItem to the top of the stack.
• Pop -- Throws exception if stack is empty; otherwise removes the item at the top of the stack.
• ItemType Top -- Throws exception if stack is empty; otherwise returns a copy of the top item

class StackType { public:

StackType( );

bool IsFull () const;

bool IsEmpty() const;

void Push( ItemType item );

void Pop();

ItemType Top();

private: int top; ItemType items[MAX_ITEMS]; };

What are the

pre and post

conditions?

// File: StackType.cpp

#include "StackType.h" #include StackType::StackType( ) { top = -1; } bool StackType::IsEmpty() const { return(top == -1); }

bool StackType::IsFull() const { return (top == MAX_ITEMS-1); }

Class Interface Diagram

(Memory reversed to better illustrate concept)

StackType class

StackType

Pop

Push

IsFull

IsEmpty

Private data: top

[MAX_ITEMS-1]

.. . [ 2 ] [ 1 ] Top^ items^ [ 0 ]

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

Private data:

top

[ MAX_ITEMS-1 ]

. . . [ 2 ]

[ 1 ] items [ 0 ]

letter ‘V’

Tracing Client Code

letter ‘V’

Private data:

top 0

[ MAX_ITEMS-1 ]

. . . [ 2 ]

[ 1 ]

items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

letter ‘V’

Private data:

top 1

[ MAX_ITEMS-1 ]

. . . [ 2 ]

[ 1 ] ‘ C ’

items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

letter ‘V’

Private data:

top 2

[ MAX_ITEMS-1 ]

. . . [ 2 ] ‘ S ’

[ 1 ] ‘ C ’ items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

letter ‘V’

Private data:

top 1

[ MAX_ITEMS-1 ]

. . . [ 2 ] ‘ S ’ [ 1 ] ‘ C ’ items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

letter ‘V’

Private data:

top 2

[ MAX_ITEMS-1 ]

. . . [ 2 ] ‘ K ’ [ 1 ] ‘ C ’ items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}

Tracing Client Code

letter ‘K’

Private data:

top 2

[ MAX_ITEMS-1 ]

. . . [ 2 ] ‘ K ’ [ 1 ] ‘ C ’ items [ 0 ] ‘ V ’

char letter = ‘V’; StackType charStack; charStack.Push(letter); charStack.Push(‘C’); charStack.Push(‘S’); if ( !charStack.IsEmpty( )) charStack.Pop( ); charStack.Push(‘K’); while (!charStack.IsEmpty( )) { letter = charStack.Top(); charStack.Pop(0)}