C++ ( Oop )

8/2/2019 C++ ( Oop )

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C++ ( OOP )CECE ACADEMIC TEAM

Prepared by: Sameh Attia

8/2/2019 C++ ( Oop )


Contents

Quick Revision

Structures

Functions

Objects & Classes Arrays & Strings

Operator overloading

Inheritance Pointers

Streams & Files

12/3/2011C++ (OOP) CECE Academic Team

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Quick Revision

Basic Program Construction

#include <iostream>

using namespace std;

int main(){

-----------------

-----------------return 0;

}


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Quick Revision

Output Using cout

cout << “CECE Academic Team \n”;

Variables & Data types

Input with cin

int x;

cin >> x;

Arithmetic Operators

+ - * / % ++ -- += -=

Relational Operators

> < == != >= <=


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Quick Revision

Logical Operators

&& || !

Bitwise Operators

& | ^(xor) << >> ~

Ternary Operator

Y=x<10 ? a : b ;

Loops1. For Loop

2. While Loop

3. Do Loop


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For Loop


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While Loop


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Do Loop


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Quick Revision

Decisions

1. if Statement

2. if...else Statement

3. Switch Statement


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If Statement


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If .. Else Statement


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Switch Statement


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Structures


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Structures

Definition:

A structure is a collection of simple variables. Thevariables in a structure can be of different types.


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Defining the Structure


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Defining a Structure Variable


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Structures

Accessing Structure Members

//give values to structure members

part1.modelnumber = 6244;

part1.partnumber = 373;part1.cost = 217.55;

//display structure members

cout << “Model “ << part1.modelnumber; cout << “, part “ << part1.partnumber;

cout << “, costs $” << part1.cost << endl;


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Structures

Initializing Structure Members

part part1 = { 6244, 373, 217.55 };

Structure Variables in Assignment Statements

Part part2;part2 = part1;

Arithmatic & Relational Opeartions

part1+part2; //ILLEGAL Statementif( part1 == part2 ) //ILLEGAL Statement

part1.cost+part2.cost; //Legal Statement


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Structures

Structures Within Structures

struct Distance

{

int feet;

float inches;};

struct Room

{

Distance length;Distance width;

};


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Structures

Structures Within Structures

Int main()

{

Room dining;

dining.length.feet = 13;

dining.length.inches = 6.5;

dining.width.feet = 10;

dining.width.inches = 0.0;Return 0;

}


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Structures

Initializing Nested Structures

Room dining = { {13, 6.5}, {10, 0.0} };

Exercisewrite a program that obtains two time values from theuser in 12:59:59 format, stores them in struct timevariables, converts each one to seconds (type int), adds

these quantities, converts the result back to hours-minutes-seconds, stores the result in a time structure, andfinally displays the result in 12:59:59 format.


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Enumerations


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Enumerations

Enumerated types work when you know in advancea finite (usually short) list of values that a data typecan take on.


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Enumerations’ Declaration


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Enumerations

Example

enum days_of_week { Sun, Mon, Tue, Wed, Thu, Fri, Sat };

int main()

{

days_of_week day1, day2; //define variables of type days_of_week

day1 = Mon;

day2 = Thu;

int diff = day2 - day1; //can do integer arithmetic

cout << “Days between = “ << diff << endl;

if(day1 < day2) //can do comparisonscout << “day1 comes before day2 \n”;

return 0;

}


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Functions


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Functions

A function groups a number of program statements into aunit and gives it a name. This unit can then be invoked fromother parts of the program.

The most important reason to use functions is to aid in theconceptual organization & clarity of a program.

Another reason is to reduce program size. Any sequence ofinstructions that appears in a program more than once is a

candidate for being made into a function. The function’scode is stored in only one place in memory, even though thefunction is executed many times in the course of theprogram.


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Functions


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Functions

The Function Declaration

Just as you can’t use a variable without first tellingthe compiler what it is, you also can’t use a function

without telling the compiler about it.

Calling the Function

The Function Definition

The definition contains the actual code for the function.


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Functions


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Functions

Example:

void starline()

{

for(int j=0; j<45; j++)

cout << ‘*’;

cout << endl;}

int main()

{

starline(); //call to function

cout << “CECE” << endlstarline(); //call to function

return 0;

}


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Functions

Passing Arguments to Functions

An argument is a piece of data (an int value, for

example) passed from a program to the function.

1. Passing Constants

2. Passing Variables

a) Passing by Value

b) Passing Structuresc) Passing by Reference


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Functions

Passing Contstants

void repchar(char, int); //function declaration

int main()

{

repchar(‘-’, 43); //call to function

return 0;

}

void repchar(char ch, int n) //function declarator

{

for(int j=0; j<n; j++) //function bodycout << ch;

cout << endl;

}


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Functions

Passing Variables (by Value)

void repchar(char, int); //function declaration

int main()

{

char chin;

int nin;

cout << “Enter a character: “;

cin >> chin;

cout << “Enter number of times to repeat it: “;

cin >> nin;repchar(chin, nin);

return 0;

}


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Functions

Passing Variables (by Value)

void repchar(char ch, int n) //function declarator

{

for(int j=0; j<n; j++) //function body

cout << ch;

cout << endl;

}


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Passing by Value


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Functions

Returning Values from Functions

When a function completes its execution, it canreturn a single value to the calling program.


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Functions

Example

float lbstokg(float); //declaration

int main()

{

float lbs, kgs;cout << “\nEnter your weight in pounds: “;

cin >> lbs;

kgs = lbstokg(lbs);

cout << “Your weight in kilograms is “ << kgs << endl;return 0;

}


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Functions

Example

float lbstokg(float pounds)

{

float kilograms = 0.453592 * pounds;

return kilograms;

}


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Functions


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Functions

Passing by Reference

Passing arguments by reference uses a differentmechanism. Instead of a value being passed to thefunction, a reference to the original variable, in the

calling program, is passed. (It’s actually the memoryaddress of the variable that is passed)

An important advantage of passing by reference is thatthe function can access the actual variables in thecalling program. Among other benefits, this provides amechanism for passing more than one value from thefunction back to the calling program.


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Functions

Example

void order(int&, int&); //prototype

int main()

{

int n1=99, n2=11;

int n3=22, n4=88;order(n1, n2); //order each pair of numbers

order(n3, n4);

cout << “n1=” << n1 << endl; //print out all numbers

cout << “n2=” << n2 << endl;

cout << “n3=” << n3 << endl;cout << “n4=” << n4 << endl;

return 0;

}


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Functions

Example

void order(int& numb1, int& numb2) //orders two numbers

{

if(numb1 > numb2) //if 1st larger than 2nd,

{

int temp = numb1; //swap them

numb1 = numb2;

numb2 = temp;}

}


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Functions

Overloaded Functions

An overloaded function appears to performdifferent activities depending on the kind of data

sent to it.


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Functions

Example

void repchar(); //declarations

void repchar(char);

void repchar(char, int);

int main()

{

repchar();repchar(‘=’);

repchar(‘+’, 30);

return 0;

}

void repchar()

{for(int j=0; j<45; j++) // always loops 45 times

cout << ‘*’; // always prints asterisk

cout << endl;

}


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Functions

Example

void repchar(char ch)

{

for(int j=0; j<45; j++) // always loops 45 times

cout << ch; // prints specified character

cout << endl;

}

void repchar(char ch, int n)

{

for(int j=0; j<n; j++) // loops n times

cout << ch; // prints specified character

cout << endl;

}


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Overloaded Functions


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Functions

Default arguments

Surprisingly, a function can be called withoutspecifying all its arguments. This won’t work on just

any function: The function declaration must providedefault values for those arguments that are notspecified.


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Functions

Example

void repchar(char=’*’, int=45); //declaration with default arguments

int main()

{

repchar(); //prints 45 asterisks

repchar(‘=’); //prints 45 equal signs

repchar(‘+’, 30); //prints 30 plus signs

return 0;

}

void repchar(char ch, int n)

{

for(int j=0; j<n; j++) //loops n timescout << ch; //prints ch

cout << endl;

}


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Functions

Recursion Functions

Recursion involves a function calling itself.

Example (calculates factorials)

unsigned long factfunc(unsigned long); //declaration

int main()

{

int n; //number entered by user

unsigned long fact; //factorial

cout << “Enter an integer: “;

cin >> n;

fact = factfunc(n);cout << “Factorial of “ << n << “ is “ << fact << endl;

return 0;

}


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Functions

unsigned long factfunc(unsigned long n){

if(n > 1)

return n * factfunc(n-1); //self call

else

return 1;

}

Assume n =5 Call 5

Call 4

Call 3

Call 2

Call 1

Return 1Return 2

Return 6

Return 24

Return 120


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Functions

Inline Functions

This kind of function is written like a normal functionin the source file but compiles into inline code

instead of into a function. The source file remainswell organized and easy to read, since the functionis shown as a separate entity. However, when theprogram is compiled, the function body is actually

inserted into the program wherever a function calloccurs.


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Functions

Example

inline float lbstokg(float pounds)

{

return 0.453592 * pounds;

}

int main(){

float lbs;

cout << “\nEnter your weight in pounds: “;

cin >> lbs;

cout << “Your weight in kilograms is “ << lbstokg(lbs)<< endl;

return 0;

}


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Functions

Scope & Storage Class

There are two types of scope

• Variables with local scope are visible only within a block.

• Variables with file scope are visible throughout a file.

There are two storage classes: automatic and static.

• Variables with storage class automatic exist during the

lifetime of the function in which they’re defined. • Variables with storage class static exist for the lifetime of

the program.


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Functions

Scope & Storage Class

1. Local Variable

2. Global Variable

3. Static Local Variable


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Functions

Example For Static Local Variable

float getavg(float); //declaration

int main()

{

float data=1, avg;

while( data != 0 ){

cout << “Enter a number: “;

cin >> data;

avg = getavg(data);

cout << “New average is “ << avg << endl;}

return 0;

}


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Functions

Example For Static Local Variable

float getavg(float newdata)

{

static float total = 0; //static variables are initializedstatic int count = 0; // only once per program

count++; //increment count

total += newdata; //add new data to total

return total / count; //return the new average

}


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Reference

Object-Oriented Programming in C++ by Lafore


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THANK YOU!

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C++ ( Oop )