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CS2303: Systems Programming Concepts

Class 14Data Structures:

DefiningUsing

ImplementingCopyright 2005-2008, Michael J. Ciaraldi

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Data Structures

You may have used some: Stack Queue Linked list Tree

We will learn how to make them.

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Data Structures

We will learn how to make them. Why? Not always available. Might have to implement. Better understanding.

Pick most appropriate.

Built-in not appropriate.E.g. kernel, time-critical.

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Defining and UsingData Structures

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StackGets it name from where?

And is it appropriate?Policy: LIFO

Where else is that used? Top

Operations: push() pop() peek() isEmpty()

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Conceptual Stack: push-down

One entry in stack

Push Push3 entries in stack

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Conceptual Stack: pop up

3 entries in stack

Pop PopPop causes empty stack

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Practical Stack

One entry in stack

Push Push Push

Sta

ck poin

ter

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Stack Options

Growth Up? Down?

Stack pointer points to: “Top” of stack? Next free cell?

Types of elements restricted/preserved?

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Stack Warnings

How to handle stack overflow?How to handle stack underflow?What is “handle”?

Detect Stack effect Return value Signal error condition

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Queue

Gets it name from where? And is it appropriate?

Policy: FIFO Where else is that used? Add at tail, remove at head.

Operations: enqueue() dequeue() peek() isEmpty()

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Conceptual Queue

One entry in queue

Enqueue Enqueue Enqueue

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Conceptual Queue

3 entries in queue

Dequeue DequeueDequeue causes

empty queue

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Practical Queue

Tail pointerHead pointer

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Queue Options

Fixed maximum size?Priority?Add/delete at both ends?

Deque = double-ended queue.Types of elements

restricted/preserved?

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Queue Warnings

How to handle wraparound?How to handle queue overflow?How to handle queue underflow?What is “handle”?

Detect Queue effect Return value Signal error condition

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Data StructureImplementation

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Implementation

Alternatives: Object-oriented Not

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Implementation

Object-oriented Each stack or queue is a separate

object. Fields: Stack data area, size, pointer. Methods: push(), pop(), etc.

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Implementation

Not Object-oriented Series of functions: create(), push(),

pop(), etc. Need identifier if more than one. Where to store specs? Risky, but done: just a stack pointer.

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Next Time

More data structures: Implementation, list, tree…