overview of c++

Overview of C++

By By

Dr. Awad KhalilDr. Awad Khalil

Computer Science DepartmentComputer Science Department

CSCI 106, Overview of C++, by Dr. Awad Khalil

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C++ Language Elements Comments make a program easier to Comments make a program easier to

understandunderstand // // Used to signify a comment on a single Used to signify a comment on a single

lineline /* Text text *//* Text text */ use if commentsuse if comments on multion multi

lineslines Don’t embed comments within Don’t embed comments within /* *//* */

commentscomments


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Compiler Directives #include#include

Compiler directiveCompiler directive Processed at compilation timeProcessed at compilation time Instructs compiler on what you want in the Instructs compiler on what you want in the

programprogram #include <iostream>#include <iostream>

Adds library files to programAdds library files to program Used with Used with < >< > Also Also “ ““ “ user defined user defined


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Compiler Directives

Stream data typeStream data type Object that is a stream of charactersObject that is a stream of characters Defined inDefined in iostreamiostream Entered on the keyboardEntered on the keyboard (cin)(cin) Displayed on monitorDisplayed on monitor (cout)(cout)


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Declarations

Direct compiler on requirementsDirect compiler on requirements Based on data needs (data identifiers)Based on data needs (data identifiers) Each identifier needed must be declaredEach identifier needed must be declared Comma used to separate identifiersComma used to separate identifiers cin and cout are undeclared identifierscin and cout are undeclared identifiers

Special elements called streamsSpecial elements called streams cin - input stream , cout - output streamcin - input stream , cout - output stream Included with the iostream not declaredIncluded with the iostream not declared


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Executable Statements

cout get outputcout get outputcout << “Enter the fabric size in square meters: ”;

cin get inputcin get inputcin >> sizeInSqmeters;

AssignmentAssignmentsizeInSqyards = metersToYards * izeInSqmeters;


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Reserved Words and Identifiers Reserved words have special meaningsReserved words have special meanings

Can NOT be used for other purposes (const, Can NOT be used for other purposes (const, float and void are some examples)float and void are some examples)

Identifiers (variables)Identifiers (variables) Used to store data by the program (user Used to store data by the program (user

defined)defined) Valid identifiers - letter, letter1, _letterValid identifiers - letter, letter1, _letter Invalid identifiers - 1letter, const, hell oInvalid identifiers - 1letter, const, hell o

Special symbolsSpecial symbols C++ has rules for special symbolsC++ has rules for special symbols= * ; { } ( ) // << >>= * ; { } ( ) // << >>


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Upper and Lower Case

C++ case sensitiveC++ case sensitive Compiler differentiates upper & lower Compiler differentiates upper & lower

casecase Identifiers can be either Identifiers can be either Be careful though (Be careful though (cost != Cost))

Blank spacesBlank spaces Use space to make program readableUse space to make program readable Use care in placing spacesUse care in placing spaces


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User-Defined Identifier An Identifier must always begin with a letter or An Identifier must always begin with a letter or

underscore symbol (not recommended)underscore symbol (not recommended)

An identifier must consist of letters, digits, or An identifier must consist of letters, digits, or underscore only.underscore only.

You cannot use a C++ reserved word as an You cannot use a C++ reserved word as an identifier.identifier.


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User-Defined Identifier

Invalid Identifiers1Letter1Letter

FloatFloat

ConstConst

Two*FourTwo*Four

Joe’sJoe’s

Two-dimensionalTwo-dimensional


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Data Types and Declarations Predefined data typesPredefined data types

intint (integers)(integers) Positive or negative whole numbersPositive or negative whole numbers 1000 1000 1212 199199 100000100000 INT_MAXINT_MAX - largest int allowed by compiler- largest int allowed by compiler

floatfloat (real numbers)(real numbers) Positive or negative decimal numbersPositive or negative decimal numbers 10.510.5 1.21.2 100.02100.02 99.8899.88

boolbool (boolean)(boolean) truetrue falsefalse

charchar (Characters)(Characters) Represent charactersRepresent characters


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Data Type: int The basic integer type is The basic integer type is intint

The size of an int depends on the machine and The size of an int depends on the machine and the compilerthe compiler

On pc’s it is normally 16 or 32 bitsOn pc’s it is normally 16 or 32 bits Other integers typesOther integers types

short: typically uses less bitsshort: typically uses less bits long: typically uses more bitslong: typically uses more bits

Different types allow programmers to use Different types allow programmers to use resources more efficientlyresources more efficiently

Standard arithmetic and relational operations are Standard arithmetic and relational operations are available for these typesavailable for these types


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Data Type: float Floating-point types represent real numbersFloating-point types represent real numbers

Integer partInteger part Fractional partFractional part

The numberThe number 108.1517108.1517 breaks down into the following breaks down into the following partsparts 108 - integer part108 - integer part 1517 - fractional part1517 - fractional part

C++ provides three floating-point typesC++ provides three floating-point types floatfloat doubledouble long doublelong double


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Data Type: char

charchar (characters)(characters)Individual character value (letter or Individual character value (letter or

number)number)Character literal enclosed in single Character literal enclosed in single

quotes ‘A’quotes ‘A’ Character type Character type charchar is is related to the related to the

integer typesinteger types Characters are encoded using a scheme Characters are encoded using a scheme

where an integer represents a particular where an integer represents a particular charactercharacter


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Character Encoding Schemes

ASCII is the dominant encoding schemeASCII is the dominant encoding scheme ExamplesExamples

' ' encoded as 32' ' encoded as 32 '+' encoded as 43'+' encoded as 43 'A' encoded as 65'A' encoded as 65 'Z' encoded as 90'Z' encoded as 90 ’ ’a' encoded as 97 a' encoded as 97 ’ ’z' encoded as 122z' encoded as 122


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Character Encoding Schemes

UNICODEUNICODE


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string Class

String object data typeString object data type A literal string constant is a sequence of A literal string constant is a sequence of

zero or more characters enclosed in zero or more characters enclosed in double quotesdouble quotes

"Are you aware?\n""Are you aware?\n" Individual characters of string are stored Individual characters of string are stored

in consecutive memory locationsin consecutive memory locations The null character (The null character ('\0''\0') is appended to ) is appended to

strings so that the compiler knows where strings so that the compiler knows where in memory strings endsin memory strings ends


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string Class

String literalString literal ““A”A” ““1234”1234” ““Enter the distance”Enter the distance”

Additional data types included in libraryAdditional data types included in library

#include <string>#include <string> Various operations on stringsVarious operations on strings


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Declarations

Identifiers should be Identifiers should be Short enough to be Short enough to be

reasonable to type (single reasonable to type (single word is norm)word is norm)

Standard abbreviations Standard abbreviations are fine (but only are fine (but only standard abbreviations)standard abbreviations)

Long enough to be Long enough to be understandableunderstandable

When using multiple When using multiple word identifiers word identifiers capitalize the first letter capitalize the first letter of each wordof each word

ExamplesExamples char response;char response; int minelement;int minelement; float score;float score; float float

temperature;temperature; int i;int i; int n;int n; char c;char c; float x;float x;


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Constant Declarations

Types of constantsTypes of constants integer integer floatfloat charchar boolbool string objectsstring objects

Associate meaningful termsAssociate meaningful terms constconst floatfloat PAYRATE = 10.25;PAYRATE = 10.25;


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Hello.cpp// FILE: Hello.cpp// FILE: Hello.cpp// DISPLAYS A USER'S NAME// DISPLAYS A USER'S NAME#include <iostream>#include <iostream>#include <string>#include <string>

using namespace std;using namespace std;

int main ()int main (){{ char letter1, letter2; char letter1, letter2; string lastName;string lastName;

// Enter letters and print message.// Enter letters and print message. cout << "Enter 2 initials and last name: ";cout << "Enter 2 initials and last name: "; cin >> letter1 >> letter2 >> lastName;cin >> letter1 >> letter2 >> lastName; cout << "Hello " << letter1 << ". " << cout << "Hello " << letter1 << ". " <<

letter2 << ". " << lastName << "! ";letter2 << ". " << lastName << "! "; cout << "We hope you enjoy studying C++." << endl;cout << "We hope you enjoy studying C++." << endl; return 0;return 0;}}


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Executable Statements Memory statusMemory status

Before and afterBefore and after AssignmentsAssignments

Form: result = expression;Form: result = expression;

sizeInSqyards = metersToYards * sizeInMeters;sizeInSqyards = metersToYards * sizeInMeters;

sum = sum + item;sum = sum + item;


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Arithmetic Operators

++ AdditionAddition - - SubtractionSubtraction ** MultiplicationMultiplication // DivisionDivision % % ModulusModulus


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Input / Output Operations

InputInput

#include <iostream> #include <iostream> librarylibrary

cin >> sizeInSqmeters;cin >> sizeInSqmeters;

OutputOutput

#include <iostream> #include <iostream> librarylibrary

cout << squareArea;cout << squareArea;


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Program Input: cinForm: Form: cin >> dataVariable;cin >> dataVariable;cin >> age >> firstInitial;cin >> age >> firstInitial;

Extracted from cin (input stream)Extracted from cin (input stream) >> Directs input to variable>> Directs input to variable cin associated with keyboard input (stdin)cin associated with keyboard input (stdin) Used with int, float, char, bool and stringsUsed with int, float, char, bool and strings Leading blanks ignored (floats, int, char,bool and strings)Leading blanks ignored (floats, int, char,bool and strings) Char read 1 at a time (1 non blank)Char read 1 at a time (1 non blank) Case issuesCase issues int or float will read until spaceint or float will read until space Stings same as int and floatStings same as int and float


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Program Output: cout

Form:Form: cout << dataVariable;cout << dataVariable;

cout << squareArea;cout << squareArea;

Output stream coutOutput stream cout << Output operator (insertion operator)<< Output operator (insertion operator)

cout << “my height in inches is: “ << height;cout << “my height in inches is: “ << height; Blank linesBlank lines

endl; or “\n”;endl; or “\n”;


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General Form of a C++ Program

General program formGeneral program form Function basic unit (collection of related Function basic unit (collection of related

statements)statements) A C++ program must contain a main functionA C++ program must contain a main function

void main ()void main () int - function returns integer valueint - function returns integer value main - lower case with ()main - lower case with () { } - Braces define the function body{ } - Braces define the function body


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General Form of a C++ Program General form of function body partsGeneral form of function body parts

Declaration statementsDeclaration statementsVariables and constantsVariables and constants

Executable statementsExecutable statementsC++ statementsC++ statements


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General Form of a C++ Program

General formGeneral form// File: filename// File: filename// Program description:// Program description:#include directives#include directivesint main()int main(){{

Declarations sectionDeclarations sectionExecutable statements sectionExecutable statements section

}}


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Arithmetic Expressions int data typeint data type

+ - * /, Assignment, input and output on int+ - * /, Assignment, input and output on int % Only used with int% Only used with int

Examples of integer divisionExamples of integer division15 / 3 = 515 / 3 = 5

15 / 2 = 715 / 2 = 7

0 / 15 = 00 / 15 = 0

15 / 0 15 / 0 undefinedundefined


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Modulus and Integer Used only with integer and yields remainderUsed only with integer and yields remainder Examples of integer modulusExamples of integer modulus

7 % 2 = 17 % 2 = 1

299 % 100 = 99299 % 100 = 99

49 % 5 = 449 % 5 = 4

15 % 0 undefined15 % 0 undefined


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Mixed-type Assignments

Expression evaluated Expression evaluated Result stored in the variable on the left sideResult stored in the variable on the left side C++ can mix typesC++ can mix types

float a, b, x;float a, b, x;

int m, n;int m, n;

a=10;a=10;

b=5;b=5;

x = m / n;x = m / n;


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Expressions With Multiple Operators Operator precedence tells how to evaluate Operator precedence tells how to evaluate

expressionsexpressions Standard precedence orderStandard precedence order

()() Evaluated first, if nested innermostEvaluated first, if nested innermostdone firstdone first

* / %* / % Evaluated second. If there are Evaluated second. If there are several,several,

then evaluate from left-to-rightthen evaluate from left-to-right + -+ - Evaluate third. If there are several,Evaluate third. If there are several,

then evaluate from left-to-rightthen evaluate from left-to-right


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Mathematical Formulas in C++

a = bc not valid C++ syntaxa = bc not valid C++ syntax * Operator* Operator a = b * c;a = b * c;

m = m = y - b y - b x - ax - a

( ) And /( ) And / m = (y - b) / (x - a);m = (y - b) / (x - a);


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Example 1: Milesbatch.cpp// File: milesBatch.cpp// File: milesBatch.cpp

// Converts distance in miles to // Converts distance in miles to kilometers.kilometers.

#include <iostream>#include <iostream>


int main() // start of main functionint main() // start of main function

{{

const float KM_PER_MILE = 1.609; const float KM_PER_MILE = 1.609;

float miles, float miles,

kms; kms;


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Milesbatch.cpp

// Get the distance in miles.// Get the distance in miles.

cin >> miles;cin >> miles;

cout << "The distance in miles is " << cout << "The distance in miles is " <<

miles << endl;miles << endl;

// Convert the distance to kilometers.// Convert the distance to kilometers.

kms = KM_PER_MILE * miles;kms = KM_PER_MILE * miles;

// Display the distance in kilometers.// Display the distance in kilometers.

cout << "The distance in kilometers is " <<cout << "The distance in kilometers is " <<

kms << kms << endl;endl;

return 0;return 0;

}}


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Milesbatch.cpp

Program outputProgram output

The distance in miles is 10The distance in miles is 10

The distance in kilometers is 16.09The distance in kilometers is 16.09


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Example 2: Coin Collection Case Study

Problem statementProblem statement Saving nickels and pennies and want to Saving nickels and pennies and want to

exchange these coins at the bank so need exchange these coins at the bank so need to know the value of coins in dollars and to know the value of coins in dollars and cents.cents.

AnalysisAnalysis Count of nickels and pennies in totalCount of nickels and pennies in total Determine total valueDetermine total value Use integer division to get dollar valueUse integer division to get dollar value

/ 100/ 100


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Coin Collection Case Study Analysis (cont)Analysis (cont)

Use modulus % to get cents valueUse modulus % to get cents value % 100% 100

DesignDesign Prompt for namePrompt for name Get count of nickels and penniesGet count of nickels and pennies Compute total valueCompute total value Calculate dollars and centsCalculate dollars and cents Display resultsDisplay results


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Coin Collection Case Study

ImplementationImplementation Write C++ code of designWrite C++ code of design Verify correct data types neededVerify correct data types needed Mixed mode types and promotionMixed mode types and promotion

TestingTesting Test results using various input combinationsTest results using various input combinations


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Coins.cpp// File: coins.cpp// File: coins.cpp// Determines the value of a coin collection// Determines the value of a coin collection

#include <iostream>#include <iostream>#include <string>#include <string>


int main()int main(){{// Local data ...// Local data ... string name;string name; int pennies; int pennies; int nickels; int nickels; int dollars; int dollars; int change; int change; int totalCents; int totalCents;

// Prompt sister for name.// Prompt sister for name. cout << "Enter your first name: ";cout << "Enter your first name: "; cin >> name;cin >> name;


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Coins.cpp // Read in the count of nickels and pennies.// Read in the count of nickels and pennies. cout << "Enter the number of nickels: ";cout << "Enter the number of nickels: "; cin >> nickels;cin >> nickels; cout << "Enter the number of pennies: ";cout << "Enter the number of pennies: "; cin >> pennies;cin >> pennies;

// Compute the total value in cents.// Compute the total value in cents. totalCents = 5 * nickels + pennies;totalCents = 5 * nickels + pennies;

// Find the value in dollars and change.// Find the value in dollars and change. dollars = totalCents / 100;dollars = totalCents / 100; change = totalCents % 100;change = totalCents % 100; // Display the value in dollars and change.// Display the value in dollars and change. cout << "Good work " << name << '!' << endl;cout << "Good work " << name << '!' << endl; cout << "Your collection is worth " << cout << "Your collection is worth " <<

dollars << " dollars and " << dollars << " dollars and " << change << " cents." << endl;change << " cents." << endl;

return 0;return 0;}}


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Coins.cpp

Program outputProgram output

Enter your first name and press return: SallyEnter your first name and press return: Sally

Enter number of nickels and press return: 30Enter number of nickels and press return: 30

Enter number of pennies and press return: 77Enter number of pennies and press return: 77

Good work sally!Good work sally!

Your collection is worth 2 dollars and 27 Your collection is worth 2 dollars and 27 cents.cents.


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Interactive Mode, Batch and Data Files Two modes interactive or batchTwo modes interactive or batch

Keyboard input interactiveKeyboard input interactive Batch mode data provided prior to startBatch mode data provided prior to start

File as inputFile as input Input / output redirectionInput / output redirection

Direct input to program use ‘<‘ symbolDirect input to program use ‘<‘ symbol Direct output to a file use ‘>‘ symbolDirect output to a file use ‘>‘ symbol


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Input / Output Redirection Program name < datafileProgram name < datafile

Metric < mydataMetric < mydata Program name > outFileProgram name > outFile

Metric > outFileMetric > outFile

Input and output redirectionInput and output redirection

Metric < inFile > outFileMetric < inFile > outFile


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Common Programming Errors SyntaxSyntax

Programs rarely compilePrograms rarely compile Something always goes wrongSomething always goes wrong Systematic solutionsSystematic solutions

Compiler not descriptiveCompiler not descriptive Look at line number before and after errorLook at line number before and after error Watch missing ; and }Watch missing ; and }

Run-time errorsRun-time errors Illegal operation (divide by 0)Illegal operation (divide by 0)

Logic errorsLogic errors Program functions differently than you expectProgram functions differently than you expect

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