C++ for Engineers and Scientists - Problem Solving Using C++

Problem Solving Using C++

Objectives

•Introduction to C++

•Programming Style

•Data Types

•Arithmetic Operations

•Variables and Declaration Statements

•Applying the Software Development Procedure

•Applications

•Common Programming Errors

 

Introduction to C++

•Modular Program: a program consisting of interrelated segments arranged in a logical and understandable form

–Easier to develop, correct, and modify than other kinds of programs

•Module: a small segment which is designed to perform a specific task

–A group of modules is used to construct a modular program

 

 

•Modules in C++ can be classes or functions

•Function: accepts an input and produces an output by processing the input in some fashion

•A function’s processing is encapsulated and hidden within the function

•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

•Rules for forming identifier names:

–First character must be a letter or underscore

–Only letters, digits, or underscores may follow the initial letter (no blanks allowed)

–Keywords cannot be used as identifiers

–Max length of an identifier = 1024 characters

•Use underscores to separate multiple words in a name, or capitalize the first letter of each word

 

 

•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()   c3po()     r2d2()     theForce()

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

                                         

Introduction to C++: The main() Function

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

•All other functions are invoked from main()

 

•Function header line: the first line of a function, 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 the function when it is invoked (if any)

•Arguments: the data passed into a function

•Function body: the statements inside a function (enclosed in braces)

 

 

•Each statement inside the function must be terminated with a semicolon

•return: a keyword causing the appropriate value to be returned from the function

•return 0 in the main() function causes the program to end

Figure 2.4  The structure of a main() function.

 

Introduction to C++: The cout Object

•cout object: an output object that sends data to a standard output display device

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

•#include : causes the named file 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) of a C++ program

 

•Escape sequence: one or more characters preceded by a backslash, \

 

Programming Style

Programming 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

 

 

•Block Comment: a comment that spans across two or more lines

–Block comment begins with /* and ends with */

            Example:

   /* This is a block comment that

        spans

        across three lines */

 

 

Data Types

Data Types: Integer

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

     Example:  2

•char data type: individual character; any letter, digit, or special character enclosed in single quotes

     Example: ‘A’

•Character values are usually stored in ASCII code

 

 

•Escape character: the backslash, \; indicates an escape sequence

•Escape sequence: tells compiler to treat the following characters as special instruction codes

Escape sequences

•bool data type: represents Boolean (logical) data; restricted to two values: true or false

•sizeof operator: shows the number of bytes used to store values of any data type

•Values returned by sizeof are compiler dependent

•Signed data type: one that permits negative, positive, and zero values

•Unsigned data type: permits only positive and zero values

•An unsigned data type provides essentially double the range of its signed counterpart

 

Data Types: Floating-Point Types

•Floating-point number (real number): zero or any positive or negative number containing a decimal 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)

–long double

 

 

Data Types: Exponential Notation

•Floating point numbers can be written in exponential notation, where e stands for exponent

Arithmetic Operations

Arithmetic Operations:
Expression Types

Arithmetic Operations:
Integer Division

Arithmetic Operations:
Negation

Arithmetic Operations
Summary of Operators

Arithmetic Operations:
Operator Precedence & Associativity

•Rules for writing arithmetic expressions:

–Never place  two consecutive binary arithmetic operators side by side

–Use parentheses to form groupings; contents within parentheses are evaluated first

–You may nest parentheses within other parentheses; evaluated from innermost to outermost

–Use the * operator for multiplication, not parentheses

•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

Variables and Declaration Statements

•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;

 

•Declaration statement: specifies the data type and identifier of a variable; sets up the memory location

     Syntax:       ;

•Data type is any valid C++ data type

     Example:    int sum;

•Declarations may be used anywhere in a function; usually grouped at the opening brace

 

•Character variables: declared using the char keyword

•Multiple variables of the same data type can be declared in a single declaration statement

     Example:

   double grade1, grade2, total, average;

•Variables can be initialized in a declaration

     Example:    double grade1 = 87.0

•A variable must be declared before it is used

 

•Declaring a variable causes memory to be allocated based on the data type

 

•Definition statement: a declaration that causes the 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 variable’s address

 

Applying the Software
Development 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 Trap

•Step 1: Analyze the Problem 

–Output: speed of the car

_–Inputs: emitted frequency and received frequency 

•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

Applications:
Telephone Switching Networks

•Number of lines required for a directly connected network: 

 

•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 100 subscribers

–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

 

Common Programming Errors

•Missing parentheses after main

•Missing or incorrect braces around function body

•Misspelling a reserved word

•Missing ending double quotes on string literal

•Missing semicolon at end of statement

•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

•Attempting to use a variable with no value

•Dividing integer values incorrectly

•Mixing data types in the same expression

Summary

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

•All C++ statements must be terminated by a semicolon

•Data types include int, float, bool, char

•cout object can be used to display data

•cout object requires the preprocessor command #include

•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 of storage reserved for a variable

C++ for Engineers and Scientists - Introduction

Introduction

Objectives

•Introduction to Programming

•Problem Solution and Software Development

•Algorithms

•Common Programming Errors

•Computer Hardware and Storage Concepts

Introduction 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

Introduction to Programming: Machine 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 be used

•Each class of computer has its own particular machine language

•Writing in machine language is tedious!

Introduction to Programming: Assembly Languages

•Assembly Language: programming language with symbolic names for opcodes, and decimals or labels for memory addresses

            Example:

            ADD  1, 2

            MUL  2, 3

•Assembly language programs must be translated into machine instructions, using an assembler

Introduction to Programming: Low- and High-Level Languages

•Low-level languages: languages that use instructions tied directly to one type of computer

            Examples: machine language, assembly language

•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

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

•Source code must be translated to machine instructions in one of two ways:

–Interpreter: each statement is translated individually and executed immediately after translation

Compiler: all statements are translated and stored as an executable program, or object program; execution occurs later

•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

Introduction to Programming: Procedural and Object Orientations

•Programs can also be classified by their orientation:

–Procedural: available instructions are used to create self-contained units called procedures

–Object-oriented: reusable objects, containing code and data, are manipulated

•Object-oriented languages support reusing existing code more easily

                                                           

Introduction to Programming: Application and System Software

•Application software: programs written to perform particular tasks for users

•System software: collection of programs to operate the computer system

–System software must be loaded first; called booting the system

–Bootstrap loader: a permanent, automatically executed component to start the boot process

•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

•Multi-user system: 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

Introduction to Programming: The Development of C++

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

•Early procedural languages included

–FORTRAN: Formula Translation

–ALGOL: Algorithmic Language

–COBOL: Common Business Oriented Language

–BASIC: Beginners All-purpose Symbolic Instruction Code

–Pascal

–C

•Early object-oriented language:

–C++

Problem Solution and Software Development

Problem Solution and Software Development: Phase I. Development and Design

•Program requirement:  request for a program or a statement of a problem

•After a program requirement is received, Phase I begins

•Phase I consists of four steps:

–Analysis

–Design

–Coding

–Testing

•Step 1: Analyze the Problem

–Analyst must understand

•What outputs are required

•What inputs will be needed

•How the inputs can be used to produce the desired outputs

–Failure to analyze and understand the requirements leads to a failed solution!

Figure 1.9  Second-level refinement structure diagram.

•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

•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

•Testing requires the use of meaningful, representative test data

•Impossible to test all possible combinations of data 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

Relative effort for steps in Phase I

Problem Solution and Software Development: Phase II. Documentation

•Many documents may be required, including

–Program description

–Algorithm development and changes

–Well-commented program listing

–Sample test runs

–Users’ manual

Problem Solution and Software Development: 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, and may be the primary source of revenue

•Good documentation vital for effective maintenance

Problem Solution and Software Development: Backup

•Backup:  process of making copies of program code and documentation on a regular basis

•Backup copies = insurance against loss or damage

–Consider using off-site storage for additional protection

Algorithms

•   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

Algorithms: Flowcharts

Figure 1.12  Flowchart for calculating the average of three numbers.

Common 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

Summary

•         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

•         Software engineering: discipline concerned with creating readable, efficient, reliable, and maintainable programs

•         Three phases in software development:

–        Program development and design

–        Documentation

•         Maintenance

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 of instructions and data used to operate a computer to produce a desired result

•Four fundamental control structures used in coding:

–Sequence

–Selection

–Iteration

–Invocation

Appendix: Computer Hardware and Storage Concepts

•Computer hardware: components that support the capabilities of the computer

Appendix: Computer Hardware and Storage Concepts (continued)

Appendix: Computer Hardware and Storage Concepts (continued)

Appendix: Computer Hardware and Storage Concepts (continued)

•Computer storage:

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

–Byte: grouping of 8 bits representing a single character

•Character codes: collection of patterns of 0s and 1s representing characters; examples include

–ASCII

–EBCDIC

•Number codes: patterns used to store numbers

•Two’s Complement number code: represents a decimal number as a binary number of 0s and 1s

•Word: grouping of one or more bytes

•Number of bytes in a word determines the maximum and minimum values that can be stored: