a laboratory course in c data structures 2003 7377

Schultz Composition: Northeast Compositors Cover Design: Night & Day Design Manufacturing Buyer: Therese Bräuer Printing and Binding: Courier Stoughton Cover Printing: Courier Stoughton

Data Structures

Structures

J O N E S A N D B A R T L E T T C O M P U T E R S C I E N C E

A Laboratory Course in

James Robergé Stefan Brandle David Whittington

Second Edition

Data Structures

Data Structures

S e c o n d E d i t i o n

A Laboratory Course in

James Robergé

Illinois Institute of Technology

Stefan Brandle

Taylor University

David Whittington

Taylor University

Copyright © 2003 by Jones and Bartlett Publishers, Inc.

Cover image © Douglas E Walker / Masterfile

All rights reserved No part of the material protected by this copyright notice may be reproduced or utilized

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Library of Congress Cataloging-in-Publication Data

Robergé, Jim.

A laboratory course in C++ data structures / James Robergé, Stefan Brandle, David Whittington.

p cm.

ISBN 0-7637-1976-5

1 C++ (Computer program language) I Brandle, Stefan II Whittington, David III.

Title.

QA76.73.C153R58 2003

005.13’3—dc21

2002044401 Editor-in-Chief, College: J Michael Stranz

Production Manager: Amy Rose

Associate Editor: Theresa DiDonato

Associate Production Editor: Karen C Ferreira

Production Assistant: Jenny L McIsaac

Senior Marketing Manager: Nathan J Schultz

Composition: Northeast Compositors

Cover Design: Night & Day Design

Manufacturing Buyer: Therese Bräuer

Printing and Binding: Courier Stoughton

Cover Printing: Courier Stoughton

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To my son Edward, who lets me see a world of wonder through his eyes And to my wife, Ruby, who creates that world.

—James Robergé

To Christina, Anna, and Esther: my queen and little princesses.

—Stefan Brandle

In memory of my kitty Sweetpea.

—David Whittington

• int * ptr Just for completeness, ptris a pointer to integer Both

the data pointed at and where the pointer points can be modified

It is good software engineering practice to give a function only as much access to

data as it absolutely needs The results are more complicated-looking code, but it can

save tons of time that otherwise would be spent debugging to determine how and

where something was getting magically changed So if a function uses an array but

doesn’t need to change the data, it would be best passed as const type * ptr, or

even const type * const ptr

Pointer math: Pointers can be incremented ( ++) and decremented ( ), integers

can be added or subtracted from pointers (+, +=, —, -=) or one pointer may be

subtracted from another The general rule to remember is that the arithmetic is always

done in terms of the size of the data type pointed at For example, ptr += 2means

“change what we are pointing at by 2 * sizeof the data type”; if the datatype is 8 bytes,

then ptr now points 2 * 8 = 16bytes higher ptr2 — ptr1gives you the difference

between the two pointers as a difference between the array index value of ptr2 and

ptr1, so if ptr2points to array[3]and ptr1points to array[1], ptr2 — ptr1 =

2 (since the ptr2 points to an element two elements away from ptr1) Pointer math

only makes sense in the context of an array

C-Strings: C-strings are just pointers to an array of characters The string end is

calculated by starting at item 0 in the array and moving up through the indexed

characters until a character with the value ‘\0’ is found; that is the end of the string

Note: There is a big difference between an empty string (the first item in the array has

the value ‘\0’) and a null string (the pointer has the value NULL, or (char *) 0) A

NULL pointer by our definition doesn’t point at any data

Pointers | 411