CS10 Coursewares

8/3/2019 CS10 Coursewares

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C++C++ forfor

Engineers and ScientistsEngineers and Scientists

Second EditionSecond Edition

Chapter 1

Introduction


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C++ for Engineers and Scientists, Second Edition 2

ObjectivesObjectives

Introduction to Programming

Problem Solution and Software Development

Algorithms Common Programming Errors

Computer Hardware and Storage Concepts


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Introduction to ProgrammingIntroduction to Programming

Program: self-contained set of instructions

used to operate a computer to produce a

specific result Also called software

Programming: the process of writing a

program, or software


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Introduction to Programming:Introduction to Programming:

Machine LanguageMachine Language Machine language programs, also called

executables, consist of binary instructions

Each instruction has two parts:

Instruction part: the operation to be performed;also called an opcode

Address part: memory address of the data to beused

Each class of computer has its own particularmachine language

Writing in machine language is tedious!


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Assembly LanguagesAssembly Languages

Assembly Language: programming language

with symbolic names for opcodes, and decimals

or labels for memory addressesExample:

ADD 1, 2

MUL 2, 3

Assembly language programs must be

translated into machine instructions, using an

assembler


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LowLow-- and Highand High--Level LanguagesLevel Languages

Low-level languages: languages that use

instructions tied directly to one type of computer

Examples: machine language, assemblylanguage

High-level languages: instructions resemble

written languages, such as English,and can be

run on a variety of computer types

Examples: Visual Basic, C, C++, Java


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Introduction to Programming: LowIntroduction to Programming: Low--

and Highand High--Level Languages (continued)Level Languages (continued)

Source code: the programs written in a high-or low-level language

Source code must be translated to machineinstructions in one of two ways:

Interpreter: each statement is translatedindividually and executed immediately after

translation Compiler: all statements are translated andstored as an executable program, orobjectprogram; execution occurs later


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Introduction to Programming: LowIntroduction to Programming: Low--

and Highand High--Level Languages (continued)Level Languages (continued)

Large C++ programs may be stored in two or

more separate program files due to

Use of previously written code

Use of code provided by the compiler

Modular design of the program (for reusability of

components)

Linker: combines all of the compiled code

required for the program


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Procedural and Object OrientationsProcedural and Object Orientations

Programs can also be classified by their

orientation:

Procedural: available instructions are used tocreate self-contained units called procedures

Object-oriented: reusable objects, containing

code and data, are manipulated

Object-oriented languages support reusing

existing code more easily


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Introduction to Programming: ProceduralIntroduction to Programming: Procedural

and Object Orientations (continued)and Object Orientations (continued)

Figure 1.2

Creating anexecutable C++

program.


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Application and System SoftwareApplication and System Software

Application software: programs written toperform particular tasks for users

System software: collection of programs tooperate the computer system

System software must be loaded first; calledbooting the system

Bootstrap loader: a permanent, automaticallyexecuted component to start the boot process


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(continued)(continued)

Operating system: the set of system programs

used to operate and control a computer; also

called OS Tasks performed by the OS include

Memory management

Allocation of CPU time

Control of input and output

Management of secondary storage devices


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Multi-usersystem: a system that allows more

than one user to run programs on the computer

simultaneously Multitasking system: a system that allows

each user to run multiple programs

simultaneously; also called multiprogrammed

system


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The Development of C++The Development of C++

The purpose of most application programs isto process data to produce specific results

Figure 1.3 Basic procedural operations.


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The Development of C++ (continued)The Development of C++ (continued) Early procedural languages included

FORTRAN: Formula Translation

ALGOL: Algorithmic Language

COBOL: Common Business Oriented Language

BASIC: Beginners All-purpose Symbolic

Instruction Code

Pascal C


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The Development of C++ (continued)The Development of C++ (continued)

Early object-oriented language:

C++


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Problem Solution andProblem Solution and

Software DevelopmentSoftware Development Software development procedure: method

for solving problems and creating software

solutions

Consists of three phases:

Phase I: Development and Design

Phase II: Documentation

Phase III: Maintenance

Software engineering: discipline concerned

with creating efficient, reliable, maintainable

software


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Problem Solution and SoftwareProblem Solution and Software

Development (continued)Development (continued)

Figure 1.6 The three phases of software development.


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Problem Solution andProblem Solution and

Software Development:Software Development:

Phase I. Development and DesignPhase I. Development and Design Program requirement: request for a program

or a statement of a problem

After a program requirement is received, PhaseI begins

Phase I consists of four steps:

Analysis

Design

Coding

Testing


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Development: Phase I (continued)Development: Phase I (continued)

Figure 1.7 The development and design steps.


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Step 2: Develop a Solution

Algorithm: the exact steps used to solve a

problem Algorithm is usually defined at high level, then

refined to detailed lower levels

Structure level diagrams may be used torepresent the levels of analysis


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Figure 1.8 First-level structure diagram.


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Figure 1.9 Second-level refinement structure diagram.


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Step 3: Code the Solution

Also called writing the program, and

implementing the solution Program should contain well-defined patterns or

structures of the following types:

Sequence

Selection

Iteration

Invocation


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Development: Phase I (continued)Development: Phase I (continued) Sequence: defines the order in which

instructions are executed

Selection: allows a choice between differentoperations, based on some condition

Iteration: allows the same operation to be

repeated based on some condition; also called

loopingorrepetition Invocation: involves invoking a set of

statements when needed


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Step 4: Test and Correct the Program

Testing: method to verify correctness and that

requirements are met Bug: a program error

Debugging: the process of locating an error,

and correcting and verifying the correction

Testing may reveal errors, but does not

guarantee the absence of errors


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Testing requires the use of meaningful,

representative test data

Impossible to test all possible combinations ofdata and operations in a complex program

Testing plans must be developed to ensure

good coverage in testing

Testing usually requires more time than other

steps in Phase I


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Relative effort for steps in Phase I


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Development: Phase III. MaintenanceDevelopment: Phase III. Maintenance Maintenance includes

Ongoing correction of newly discovered bugs

Revisions to meet changing user needs Addition of new features

Maintenance usually the longest phase, andmay be the primary source of revenue

Good documentation vital for effectivemaintenance


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Development: BackupDevelopment: Backup

Backup: process of making copies of program

code and documentation on a regular basis

Backup copies = insurance against loss ordamage

Consider using off-site storage for additional

protection


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AlgorithmsAlgorithms

Algorithm: the step-by-step sequence of

instructions that describe how the data is to be

processed to produce the desired output

Programming = the translation of the selected

algorithm into a language the computer can use


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Algorithms (continued)Algorithms (continued)

Example: Calculate the sum of all whole numbers from1 through 100


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Pseudocode: English-like phrases used to

describe the algorithm

Formula: description of a mathematical

equation

Flowchart: diagram showing the flow of

instructions in an algorithm

Flowcharts use special symbols


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Algorithms: FlowchartsAlgorithms: Flowcharts


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Algorithms: Flowcharts (continued)Algorithms: Flowcharts (continued)


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Algorithms: Flowcharts (continued)Algorithms: Flowcharts (continued)

Figure 1.12 Flowchart forcalculating the average of three

numbers.


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Common Programming ErrorsCommon Programming Errors

Common errors include

Starting to write the program before fully

understanding the requirements and the

algorithm to be used

Failing to make backups periodically

Failing to provide complete, precise instructions

in the programming language


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SummarySummary

Software: programs used to operate a

computer

Programming language types:

Low-level languages

Machine language (executable) programs

Assembly languages

High-level languages Compiler and interpreter languages


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Summary (continued)Summary (continued)

Software engineering: discipline concerned with

creating readable, efficient, reliable, and

maintainable programs

Three phases in software development:

Program development and design

Documentation

Maintenance


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Four steps in program development and design: Analyze the problem

Develop a solution

Code the solution Test and correct the solution

Algorithm: step-by-step procedure that

describes how a task is performed

Computer program: self-contained unit ofinstructions and data used to operate a

computer to produce a desired result


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Four fundamental control structures used in

coding:

Sequence Selection

Iteration

Invocation


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Appendix: Computer Hardware andAppendix: Computer Hardware and

Storage ConceptsStorage Concepts

Computer hardware: components that support

the capabilities of the computer


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Storage Concepts (continued)Storage Concepts (continued)

Components include:

Arithmetic and logic unit (ALU): performs

arithmetic and logic functions

Control unit: directs and monitors overall

operations

Memory unit: stores instructions and data

Input and output (I/O) unit: interfaces toperipheral devices

Secondary storage: nonvolatile permanent

storage such as hard disks


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Central processing unit (CPU), also called

microprocessor, combines the ALU and

control unit on a single chip

Figure 1.15 VLSI chip connections for a desktop computer.


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Computer storage:

Bit: smallest unit of data; value of 0 or 1

Byte: grouping of 8 bits representing a singlecharacter

Character codes: collection of patterns of 0s

and 1s representing characters; examples

include

ASCII

EBCDIC


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Number codes: patterns used to storenumbers

Twos Complement number code: represents

a decimal number as a binary number of 0s and1s


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Word: grouping of one or more bytes

Number of bytes in a word determines themaximum and minimum values that can be

stored:


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C++C++ forfor



Chapter 2Problem Solving Using C++


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Introduction to C++

Programming Style

Data Types

Arithmetic Operations

Variables and Declaration Statements


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Objectives (continued)Objectives (continued)

Applying the Software Development Procedure

Applications

Common Programming Errors


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Introduction to C++Introduction to C++

Modular Program: a program consisting ofinterrelated segments arranged in a logical andunderstandable form

Easier to develop, correct, and modify than otherkinds of programs

Module: a small segment which is designed toperform a specific task

A group of modules is used to construct amodular program


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Introduction to C++ (continued)Introduction to C++ (continued)

Figure 2.1 A well-designed program is built using

modules.


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Modules in C++ can be classes or functions

Function: accepts an input and produces an

output by processing the input in some fashion A functions processing is encapsulated and

hidden within the function


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Figure 2.2 A multiplying function.


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Class: contains both data and functions used

to manipulate the data

Function: encapsulates a set of operations,while a class encapsulates data plus one or

more sets of operations

Identifier: a name given to an element of the

language, such as a class or function


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Rules for forming identifier names:

First character must be a letter or underscore

Only letters, digits, or underscores may followthe initial letter (no blanks allowed)

Keywords cannot be used as identifiers

Max length of an identifier = 1024 characters

Use underscores to separate multiple words ina name, or capitalize the first letter of eachword


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Keywords

Keyword: a reserved name that represents a

built-in object or function of the language


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Examples of valid C++ identifiers:

degToRad intersect addNums

slope bessell multTwo

findMax density

Examples of invalid C++ identifiers:

1AB3 (begins with a number)

E*6 (contains a special character)

while (this is a keyword)


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Function names

Require a set of parentheses at the end

Can use mixed upper and lower case

Should be meaningful, or be a mnemonic

Mnemonic: a word designed as a memory aid

Examples of function names:

easy() c3 po() r2d2() theForce()

Note that C++ is a case-sensitive language!


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Introduction to C++:Introduction to C++:TheThe main()main() FunctionFunction

Overall structure of a C++ program containsone function named main(), called the driver

function All other functions are invoked from main()


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Introduction to C++:Introduction to C++:

TheThe main()main() FunctionFunction (continued)(continued)

Figure 2.3 The main() function directs all other functions.


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Introduction to C++ : TheIntroduction to C++ : The main()main()

FunctionFunction (continued)(continued)

Function header line: the first line of afunction, which contains

The type of data returned by the function (if any)

The name of the function

The type of data that must be passed into thefunction when it is invoked (if any)

Arguments: the data passed into a function Function body: the statements inside afunction (enclosed in braces)


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Introduction to C++:Introduction to C++:

TheThe main()main() FunctionFunction (continued)(continued)

Each statement inside the function must be

terminated with a semicolon

return: a keyword causing the appropriatevalue to be returned from the function

return 0 in the main() function causes the

program to end


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Introduction to C++: TheIntroduction to C++: The coutcout ObjectObject

cout object: an output object that sends datato a standard output display device


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Introduction to C++: TheIntroduction to C++: The coutcout ObjectObject


Preprocessor command: starts with a #;causes an action before the source code iscompiled into machine code

#include : causes the namedfile to be inserted into the source code

C++ provides a standard library with many pre-written classes that can be included

Header files: files included at the head (top) ofa C++ program


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Introduction to C++ : TheIntroduction to C++ : The coutcout ObjectObject


usingnamespace :

indicates where header file is located

Namespaces qualify a name; a function name

in your class can be the same as one used in astandard library class

String: any combination of letters, numbers,

and special characters enclosed in double

quotes (a delimiter)

Delimiter: a symbol that marks the beginning

and ending of a string; not part of the string


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Escape sequence: one or more characterspreceded by a backslash, \


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Programming StyleProgramming Style

Although more than one C++ statement can be

on a single line, good style calls for one

statement per line

Opening and closing braces {} for the functionbody should each be on separate lines

Statements in the function body should be

indented


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Programming Style: CommentsProgramming Style: Comments

Comments: explanatory remarks in the source

code added by the programmer

Line comment: begins with // and continues

to the end of the line

Line comment can be on a line by itself, or at the

end of a line of code

Line comment cannot be longer than one line


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Block Comment: a comment that spans across

two or more lines

Block comment begins with /* and ends with */

Example:

/* Thisisablockcommentthat

spans

acrossthreelines */


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Data TypesData Types

Data type: a set of values and the operations

that can be applied to these values

Two fundamental C++ data groupings:

Class data type (a class): created by the

programmer

Built-in data type (primitive type): part of the

C++ compiler


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Data Types (continued)Data Types (continued)

Figure 2.7 Built-in data types.


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Data Types (continued)Data Types (continued)

Literal (constant): an actual value

Examples:

3.6 //numericliteralHello //stringliteral

Integer: a whole number

C++ has 9 built-in integer data types, providing

differing amounts of storage (compiler

dependent)


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Data Types: Integer (continued)Data Types: Integer (continued)


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int data type: whole numbers, optionally with+ or sign

Example: 2

char data type: individual character; any letter,digit, or special character enclosed in singlequotes

Example: A

Character values are usually stored in ASCIIcode


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Figure 2.9 The letters BARTER stored inside a computer.


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Escape character: the backslash, \; indicates

an escape sequence

Escape sequence: tells compiler to treat thefollowing characters as special instruction

codes



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Escape sequences


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bool data type: represents Boolean (logical)

data; restricted to two values: true orfalse

sizeof operator: shows the number of bytes

used to store values of any data type

Values returned by sizeof are compiler

dependent


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Signed data type: one that permits negative,

positive, and zero values

Unsigned data type: permits only positive andzero values

An unsigned data type provides essentially

double the range of its signed counterpart


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Signed and unsigned integer data types


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Data Types: FloatingData Types: Floating--Point TypesPoint Types

Floating-point number (real number): zero orany positive or negative number containing adecimal point

Examples: +10.625 5. -6.2 No special characters are allowed

Three floating-point data types in C++:

float(single precision)

double(double precision) longdouble

D t T Fl tiD t T Fl ti P i t TP i t T


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D t T Fl tiD t T Fl ti P i t TP i t T


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float literal: append an f orF to the number

longdoubleliteral: append an l orL to the

number

Examples:

9.234 //adoubleliteral

9.234F //afloatliteral

9.234L //alongdoubleliteral


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Data Types: Exponential NotationData Types: Exponential Notation

Floating point numbers can be written in

exponential notation, where e stands for

exponent


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Arithmetic OperationsArithmetic Operations

C++ supports addition, subtraction,

multiplication, division, and modulus division

Different data types can be used in the same

arithmetic expression

Arithmetic operators are binary operators

Binary operators: require two operands


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Arithmetic Operations (continued)Arithmetic Operations (continued)

Operation Operator

Addition +

Subtraction -

Multiplication *

Division /

Modulus division %


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Arithmetic Operations (continued)Arithmetic Operations (continued)

Arithmetic Operations:Arithmetic Operations:


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Expression TypesExpression Types

Expression: any combination of operators and

operands that can be evaluated to yield a value

If all operands are the same data type, the

expression is named by the data type used(integer expression, floating-point expression,

etc.)

Mixed-mode expression: contains integer and

floating-point operands; yields a double-

precision value



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Integer DivisionInteger Division

Integer division: yields an integer result

Any fractional remainders are dropped

(truncated)

Example: 15/2 yields 7

Modulus (remainder) operator: returns only the

remainder

Example: 9 % 4 yields 1


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A ith ti O tiA ith ti O ti


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Arithmetic OperationsArithmetic OperationsSummary of OperatorsSummary of Operators



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Operator Precedence & AssociativityOperator Precedence & Associativity

Rules for writing arithmetic expressions:

Never place two consecutive binary arithmeticoperators side by side

Use parentheses to form groupings; contentswithin parentheses are evaluated first

You may nest parentheses within otherparentheses; evaluated from innermost tooutermost

Use the * operator for multiplication, notparentheses



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(continued)(continued) Expressions with multiple operators are

evaluated by precedence of operators:

All negations occur first

Multiplication, division, and modulus are next,

from left to right

Addition and subtraction are last, from left to

right



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(continued)(continued) Associativity: the order in which operators of

the same precedence are evaluated


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Variables and Declaration StatementsVariables and Declaration Statements

Variable: symbolic identifier for a memory

address where data can be held

Use identifier naming rules for variable names

Figure 2.11

Naming

storagelocations.



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Assignment statement: used to store a value

into a variable

Value of the expression on the right side of the= is assigned to the memory location of the

variable on the left side of the =

Examples:

num1 = 45;num2 = 12;

total=num1 +num2;



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Declaration statement: specifies the data typeand identifier of a variable; sets up the memorylocation

Syntax: ;

Data type is any valid C++ data type

Example: intsum;

Declarations may be used anywhere in a

function; usually grouped at the opening brace


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Declaring a variable causes memory to be

allocated based on the data type

Figure 2.12b Defining the floating-point variablenamed slope.



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Definition statement: a declaration that causesthe computer to allocate storage for the variable

Three items associated with each variable:

Data type Actual value stored in the variable (its contents)

Memory address of the variable

Address operator (&) provides the variables

address



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Applying the SoftwareApplying the Software


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Applying the SoftwareApplying the Software

Development ProcedureDevelopment Procedure

Step 1: Analyze the problem

Understand the desired outputs

Determine the required inputs Step 2: Develop a solution

Determine the algorithms to be used

Use top-down approach to design

Step 3: Code the solution

Step 4: Test and correct the program

Applications: Radar Speed TrapApplications: Radar Speed Trap


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Step 1: Analyze the Problem

Output: speed of the car

Inputs: emitted frequency and receivedfrequency

Step 2: Develop a Solution Algorithm:

Assign values to f0 and f1 Calculate and display speed

Step 3: Code the Solution Step 4: Test and Correct the Program



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Applications:Applications:


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Applications:Applications:

Telephone Switching NetworksTelephone Switching Networks

Number of lines required for a directly

connected network:

Figure 2.17 Directly connecting four telephones.

Applications: Telephone SwitchingApplications: Telephone Switching


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Networks (continued)Networks (continued)

Step 1: Analyze the Problem

Outputs: number of direct lines for 100 phones,

and additional number of lines to add 10 more

phones

Inputs: number of telephones (n)

Step 2: Develop a Solution

Calculate total number of lines for 100subscribers



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Networks (continued)Networks (continued)

Step 2: Develop a Solution (continued)

Calculate total number of lines for 110

subscribers

Subtract to get additional lines needed

Display number of lines for 100 subscribers

Display number of additional lines needed

Step 3: Code the Solution Step 4: Test and Correct the Program


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C P i EC P i E


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Missing parentheses aftermain

Missing or incorrect braces around function

body Misspelling a reserved word

Missing ending double quotes on string literal

Missing semicolon at end of statement



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Adding a semicolon at end of#include

statement

Missing \n to indicate new line Substituting letter O for zero and vice versa

Failing to declare all variables

Storing incorrect data type into a variable



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Attempting to use a variable with no value

Dividing integer values incorrectly

Mixing data types in the same expression

SS


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SummarySummary

C++ program contains one or more functions,one of which must be called main()

All C++ statements must be terminated by asemicolon

Data types include int, float, bool, char

cout object can be used to display data

cout object requires the preprocessorcommand #include

S ( ti d)S ( ti d)


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Variables must be declared with their data type

A variable can be used only after it has been

declared Variables may be initialized when declared

Definition statement causes computer to

allocate memory for a variable

sizeof() operator yields the amount ofstorage reserved for a variable


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Objecti esObjecti es


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Assignment Operations

Formatting Numbers for Program Output

Using Mathematical Library Functions Program Input Using the cin Object

Symbolic Constants



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Applications


A Closer Look: Programming Errors

Assignment OperationsAssignment Operations


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Assignment OperationsAssignment Operations

Assignment Statement: assigns the value of

the expression on the right side of the = to the

variable on the left side of the =

Another assignment statement using the same

variable will overwrite the previous value with

the new value

Examples:slope= 3.7;

slope= 6.28;

Assignment Operations (continued)Assignment Operations (continued)


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Right side of an assignment statement maycontain any expression that can be evaluated toa value

Examples:

newtotal= 18.3 +total;

taxes= .06*amount;

average=sum/items;

Only one variable can be on the left side of anassignment statement



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Assignment operator: the = sign

C++ statement: any expression terminated by

a semicolon

Multiple assignments in the same expressionare possible

Example:

a=b=c= 25;



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Coercion: forcing a data value to another data

type

Value of the expression on the right side of anassignment statement will be coerced

(converted) to the data type of the variable on

the left side during evaluation

Variable on the left side may also be used onthe right side of an assignment statement



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Additional assignment operators provide shortcuts: +=, -=, *=, /=, %=

Example:

sum=sum+ 10;

is equivalent to: sum+= 10;

price *=rate+1;

is equivalent to:price=price * (rate+ 1);



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g p ( )g p ( )

Accumulation statement: has the effect ofaccumulating, or totaling

Syntax:

variable= variable+newValue;



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Counting statement: adds a fixed value to thevariables current value

Syntax:

variable= variable+fixedNumber;

Example:

i=i+ 1;

count=count+ 1;



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Increment operator++: unary operator for thespecial case when a variable is increased by 1

Prefix increment operatorappears before the

variableExample: ++i

Postfix increment operatorappears after thevariable

Example: i++



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Example: k=++n; //prefixincrement

is equivalent to

n=n+ 1; //incrementnfirst

k=n; //assignns valuetok

Example: k=n++; //postfixincrement

is equivalent to

k=n; //assignns valuetokn=n+ 1; //andthenincrementn



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Decrement operator--: unary operator for

the special case when a variable is decreased

by 1

Prefix decrement operatorappears before the

variable

Example: --i;

Postfix decrement operatorappears after thevariable

Example: i--;

Formatting NumbersFormatting Numbers


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for Program Outputfor Program Output

Proper output formatting contributes to ease of

use and user satisfaction

cout with stream manipulators can control

output formatting

Formatting Numbers forFormatting Numbers for

P O t t ( ti d)P O t t ( ti d)


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Program Output (continued)Program Output (continued)

Table 3.1 Commonly Used Stream Manipulators




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Table 3.1 Commonly Used Stream Manipulators(continued)


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The field width manipulator must be includedfor each value in the data stream sent to cout

Other manipulators remain in effect until they

are changed

iomanip header file must be included to use

manipulators requiring arguments


P O ( i d)P O ( i d)


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Formatting floating-point numbers requires

three field-width manipulators to

Set the total width of the display

Force a decimal place

Set the number of significant digits after the

decimal point

Example:

produces this output:




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setprecision: sets the number of digits after

the decimal point if a decimal point has been

explicitly forced; otherwise, it sets the total

number of displayed digits If the field width is too small, cout ignores the

setwmanipulator setting and allocates

enough space for printing

Ifsetprecision setting is too small, thefractional part of the value is rounded to the

specified number of decimal places




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Ifsetprecision value is too large, thefractional value is displayed with its current size




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Table 3.2 Effect of Format Manipulators




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Table 3.2 Effect of Format Manipulators (continued)




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setiosflags manipulator: allows additional

formatting:

Right or left justification

Fixed display with 6 decimal places Scientific notation with exponential display

Display of a leading + sign

Parameterized manipulator: one which

requires arguments, or parameters


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To designate an octal integer constant, use a

leading zero

To designate a hexadecimal integer constant,

use a leading 0x Manipulators affect only output; the value

stored internally does not change

Formatting Numbers for ProgramFormatting Numbers for Program

O tp t (contin ed)O tp t (contin ed)


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Output (continued)Output (continued)




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Manipulators can also be set using theostreamclass methods

Separate the cout object name from the

method name with a periodExample:

cout.precision(2)




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Table 3.4 ostreamClass Methods


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Using Mathematical Library FunctionsUsing Mathematical Library Functions



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Table 3.5 Common C++ Functions




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To use a math function, give its name and pass

the input arguments within parentheses

Expressions that can be evaluated to a value

can be passed as arguments




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Function calls can be nested

Example: sqrt(sin(abs(theta)))

Cast operator: a unary operator that forces the

data to the desired data type Compile-time cast

Syntax: dataType(expression)

Example: int(a+b)




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Run-time cast: the requested conversion is

checked at run time and applied if valid

Syntax:

staticCast(expression)Example:

staticCast(a*b)

Program Input Using theProgram Input Using the cincin ObjectObject


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cin Object: allows data entry to a running

program

Use of the cin object causes the program to

wait for input from the keyboard When keyboard entry is complete, the program

resumes execution, using the entered data

An output statement preceding the cin object

statement provides a prompt to the user




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cincan accept multiple input values to be

stored in different variables

Multiple numeric input values must be

separated by spacesExample:

cin>>num1 >>num2

with keyboard entry: 0.052 245.79




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( ti d)( ti d)


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User-input validation: the process of

ensuring that data entered by the user matches

the expected data type

Robust program: one that detects and

handles incorrect user entry

Symbolic ConstantsSymbolic Constants


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Symbolic constant: a constant value that isdeclared with an identifier using the const

keyword

A constants value may not be changedExample:

constint MAXNUM= 100;

Good programming places statements inappropriate order

Symbolic Constants (continued)Symbolic Constants (continued)


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Proper placement of statements:preprocessordirectives

intmain()

{

symbolicconstants

mainfunctiondeclarations

otherexecutablestatements

return value

}

ApplicationsApplications


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Acid Rain: develop a program to calculate the

pH level of a substance based on user input of

the concentration of hydronium ions

Approximating the Exponential Function:develop a program that approximates ex



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Failure to declare or initialize variables before

use

Failure to include the preprocessor statement

when using a C++ preprogrammed library Passing the incorrect number or type of

arguments to a function

Applying increment or decrement operator to an

expression instead of an individual variable




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Failure to separate all variables passed to cin

with the extraction symbol >>

Failure to test thoroughly

Compiler-dependent evaluation whenincrement or decrement operators are used

with variables that appear more than once in

the same expression

SummarySummary


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Expression: a sequence of one or more

operands separated by operators

Expressions are evaluated based on

precedence and associativity Assignment operator: =

Increment operator: ++

Decrement operator: --



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Use #include for math functions

Arguments to a function must be passed in the

proper number, type, and order

Functions may be included within largerexpressions

cin object provides data input from a

keyboard; program is suspended until the input

arrives



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Use a prompt to alert the user to provide input

Constants are named values that do not

change

A Closer Look: Programming ErrorsA Closer Look: Programming Errors


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Program errors may be detected in four ways:

Before a program is compiled (desk checking)

While it is being compiled (compile-time errors)

While it is being run (run-time errors) While examining the output after completion

Errors may be

Typos in the source code

Logic errors

A Closer Look: Programming ErrorsA Closer Look: Programming Errors


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Logic errors: often difficult to detect, and difficult

to find the source

Program tracing: stepping through the

program by hand or with a trace tool Debugger: program that allows the interruption

of a running program to determine values of its

variables at any point


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C++C++ forfor



Chapter 4Selection Structures



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Selection Criteria

The if-then-else Statement

Nested if Statements

The switch Statement

Applications



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A Closer Look at Program Testing

Selection CriteriaSelection Criteria


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if-else statement: implements a decision

structure for two alternatives

Syntax:

if (condition)

statement executed if condition is true;

else

statement executed if condition is false;

Selection Criteria (continued)Selection Criteria (continued)


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The condition is evaluated to its numerical

value:

A non-zero value is considered to be true

A zero value is considered to be false The else portion is optional; it is executed only

if the condition is false

The condition may be any valid C++ expression



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Relational expression: compares two

operands or expressions using relational

operators



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Relational expressions are evaluated to a

numerical value of 1 or 0 only:

If the value is 1, the expression is true

If the value is 0, the expression is false char values are automatically coerced to int

values for comparison purposes

Strings are compared on a character by

character basis; the string with the first lowercharacter is considered smaller

Selection Criteria (continued)Selection Criteria (continued)E l f t i i


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Examples of string comparisons:



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Logical operators

AND (&&): condition is true only if both

expressions are true

OR (||): condition is true if either one or both of

the expressions is true

NOT (!): changes an expression to its opposite

state; true becomes false, false becomes true



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Precedence and Associativity of Operators


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TheThe ifif--elseelse StatementStatement


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if-else performs instructions based on theresult of a comparison

Place statements on separate lines for readability

Syntax:

TheThe ifif--elseelse Statement (continued)Statement (continued)


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Figure 4.2The if-else

flowchart.


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Compound statement: a sequence of singlestatements contained between braces, creating ablock of statements

Block of statements can be used anywhere that a

single statement is legal Any variable declared within a block is usable only

within that block

Scope: the area within a program where a variable

can be used; a variables scope is based on wherethe variable is declared



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One-way selection: anif statement without the

optional else portion



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Common problems with if-else statements:

Misunderstanding what an expression is

Using the assignment operator (=) instead of the

relational operator (==)

NestedNested ifif StatementsStatements


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if-else statement can contain any valid C++

statement, including another if-else

Nested if statement: an if-else statement

completely contained within anotherif-else Use braces to block code, especially when

innerifstatement does not have its ownelse

NestedNested ifif Statements (continued)Statements (continued)


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Figure 4.5aif-else

statement

nested in anif.



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if-elsechain: a nested if statement

occurring in the else clause of the outerif-else

If any condition is true, the correspondingstatement is executed and the chain terminates

Final else is only executed if no conditions

were true; serves as a catch-all case

if-else chain provides one selection from

many possible alternatives



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Figure 4.5b if-else

statement nested in anelse.

General form of anif-elsechain.



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TheThe switchswitch StatementStatement


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switch statement: provides for one selectionfrom many alternatives

switch keyword starts the statement; isfollowed by the expression to be evaluated

case keyword identifies a value to be comparedto the switch expression; when a match isfound, statements in this case block areexecuted

All further cases after a match is found areexecuted unless a break statement is found

TheThe switchswitch Statement (continued)Statement (continued)


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default case is executed if no other casevalue matches were found

default case is optional



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Using the assignment operator (=) instead of

the relational operator (==) for an equality test

Assuming a structural problem with an if-else

causes the error instead of focusing on the datavalue being tested

Using nested if statements without braces to

define the structure

SummarySummary


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Relational expressions, or conditions, are used

to compare operands

If the relation expression is true, its value is 1;

if false, its value is 0 Use logical operators && (AND), || (OR), and

! (NOT) to construct complex conditions

if-else allows selection between two

alternatives



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An if expression that evaluates to 0 is false; if

non-zero, it is true

if statements can be nested

Chained if statement provides a multiwayselection

Compound statement contains any number of

individual statements enclosed in braces



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switch statement provides a multiwayselection

switch expression is evaluated and compared

to each case value; if a match is found,

execution begins at that cases statements andcontinues unless a break is encountered


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C++C++ forforEngineers and ScientistsEngineers and Scientists


Chapter 5

Repetition Statements



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Basic Loop Structures

while Loops

Interactive while Loops

for loops

Loop Programming Techniques



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Nested Loops

do while Loops


Basic Loop StructuresBasic Loop Structures


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Repetition structure has four required elements:

Repetition statement

Condition to be evaluated

Initial value for the condition

Loop termination

Repetition statements include

while

for dowhile

Basic Loop Structures (continued)Basic Loop Structures (continued)


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The condition can be tested

At the beginning: pretest orentrance-

controlled loop

At the end: posttest orexit-controlled loop

Something in the loop body must cause the

condition to change, to avoid an infinite loop,

which never terminates

whilewhile LoopsLoops


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while statement is used to create a whileloop

Syntax: while (expression)

statement;

Statements following the expressions are

executed as long as the expression condition

remains true (evaluates to a non-zero value)

whilewhile Loops (continued)Loops (continued)


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Figure 5.3

Anatomy of awhile loop.

whilewhile Loops (continued)Loops (continued)


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InteractiveInteractive whilewhileLoopsLoops


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Combining interactive data entry with thewhile statement provides for repetitive entry

and accumulation of totals

InteractiveInteractive whilewhileLoops (continued)Loops (continued)


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break statement: forces an immediate break,or exit, from switch, while, for, and do-

while statements

break statement violates pure structuredprogramming, but is useful for breaking out of

loops when an unusual condition is detected


Example of a break statement:


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p



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continue statement: applies to while, do-while, and for statements; causes the nextiteration of the loop to begin immediately

continue statement is useful for skipping overdata that should not be processed in thisiteration, while staying within the loop

Null statement: a semicolon with nothingpreceding it; a do-nothing statement required

for syntax purposes only

forfor LoopsLoops


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forstatement: a loop with a fixed countcondition that handles alteration of the condition

Syntax:for (initializing list; expression; altering list)

statement;

Initializing list: sets the starting value of a

counter

Expression: contains the maximum or

minimum value the counter can have;determines when the loop is finished

forfor Loops (continued)Loops (continued)

Altering list: provides the increment value that


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is added or subtracted from the counter in eachiteration of the loop

If initializing list is missing, the counter initialvalue must be provided prior to entering the for

loop If altering list is missing, the counter must be

altered in the loop body

Omitting the expression will result in an infinite

loop



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Figure 5.7for loop

flowchart.

Loop Programming TechniquesLoop Programming Techniques


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These techniques are suitable for pretest loops(for and while):

Interactive Input within a Loop

Includes a cin statement within a while orfor

loop Selection within a Loop

Using a for orwhile loop to cycle through a setof values to select those values that meet somecriteria




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Evaluating Functions of One Variable

Used for functions that must be evaluated over a

range of values

Noninteger increment values can be used




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Interactive Loop Control

Variable is used to control the loop repetitions

Provides more flexibility at run-time




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Nested LoopsNested Loops


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Nested loop: a loop contained within anotherloop

All statements of the inner loop must becompletely contained within the outer loop; no

overlap allowed Different variables must be used to control each

loop

For each single iteration of the outer loop, the

inner loop runs through all of its iterations


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Nested Loops (continued)Nested Loops (continued)


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dowhiledowhile LoopsLoops

l i tt t l


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dowhile loop is a posttest loop Loop continues while the condition is true

Condition is tested at the end of the loop

Syntax:

do

statement;

while (expression);

All statements are executed at least once in aposttest loop

dowhiledowhile Loops (continued)Loops (continued)


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Figure 5.11The do

statements

flow ofcontrol.

dowhiledowhile Loops: Validity ChecksLoops: Validity Checks


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Useful in filtering u

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