برمجة لغة سي بلص بلص pptx - ندى شندالة

What Is Programming and Program Development Life Cycle ?

Programming is a process of problem solving

Step 1: Analyze the problem

Outline the problem and its requirements
Design steps (algorithm) to solve the problem

Step 2: Implement the algorithm

Implement the algorithm in code
Verify that the algorithm works

Step 3: Maintenance

Use and modify the program if the problem domain changes

Algorithm:

Step-by-step problem-solving process
1

The Problem Analysis–Coding–Execution Cycle
Understand the Overall problem

Understand problem requirements

Does program require user interaction?
Does program manipulate data?
What is the output?

If the problem is complex, divide it into subproblems

Analyze each subproblem as above
2

The Problem Analysis–Coding–Execution Cycle (cont'd.)

Run code through compiler

If compiler generates errors

Look at code and remove errors
Run code again through compiler

If there are no syntax errors

Compiler generates equivalent machine code

Linker links machine code with system resources

3

The Problem Analysis–Coding–Execution Cycle (cont'd.)

Once compiled and linked, loader can place program into main memory for execution

The final step is to execute the program

Compiler guarantees that the program follows the rules of the language
Does not guarantee that the program will run correctly
C++ Programming: From Problem Analysis to Program Design, Fifth Edition
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The Language of a Computer

Machine language: language of a computer

Binary digit (bit):

The digit 0 or 1

Binary code:

A sequence of 0s and 1s

Byte:
A sequence of eight bits
5

The Evolution of Programming Languages

Early computers were programmed in machine language

To calculate wages = rates * hours in machine language:

100100 010001 //Load
100110 010010 //Multiply
100010 010011 //Store
C++ Programming: From Problem Analysis to Program Design, Fifth Edition
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The Evolution of Programming Languages

Assembly language instructions are mnemonic

Assembler: translates a program written in assembly language into machine language

C++ Programming: From Problem Analysis to Program Design, Fifth Edition
7

The Evolution of Programming Languages
Using assembly language instructions, wages = rates • hours can be written as:

LOAD rate

MULT hour
STOR wages
8

The Evolution of Programming Languages

High-level languages include Basic, FORTRAN, COBOL, Pascal, C, C++, C#, and Java

Compiler: translates a program written in a high-level language machine language

The equation wages = rate • hours can be written in C++ as:
wages = rate * hours;
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The Problem Analysis–Coding–Execution Cycle

10
Errors
Errors
Using Any Programming Language
Translate Code To Machine Language

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Then

Think

Write Code

Basic Definitions
12
Programming language:
a set of rules, symbols, and special words used to write computer programs.

Computer program

Sequence of statements whose objective is to accomplish a task.

Syntax:

rules that specify which statements (instructions) are legal

Computer System

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Input
Output

Processing

Example 1

Write a program to find the Area of a rectangle

The area of the Rectangle are given by the following formula:

Area = Rect Length * Rect Width.

Input :

Rectangle Length , Rectangle Width.

Processing :

Area = Rect Length * Rect Width.

Output :

Print Out The area.

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Example 2

Write a program to find the perimeter and area of a square

The perimeter and area of the square are given by the following formulas:
perimeter = Side Length * 4
area = Side Length * Side Length
Input:
Square Side Length
Processing:
perimeter = Side Length * 4
area = Side Length * Side Length
• Output:
Print Out The Perimeter and Area.

15

Your First C++ Program

#include <iostream>
using namespace std;
int main()
{
// This program is written by ahmad

cout << "My first C++ program." << endl;

return 0;
}

Sample Run:
My first C++ program.
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Processing a C++ Program (cont'd.)

To execute a C++ program:
Use an editor to create a source program in C++

Preprocessor directives begin with # and are processed by a the preprocessor

Use the compiler to:
Check that the program obeys the rules
Translate into machine language (object program)

Linker:

Combines object program with other programs provided by the SDK to create executable code

Loader:

Loads executable program into main memory

The last step is to execute the program

Processing a C++ Program (cont'd.)

Interacting With User: Displaying Messages on Screen

In C++ , we use Cout << “ Text To be Displayed on The screen “ ;
To use Cout << , we must use
#include <iostream> ;
using namespace std;

#include <iostream> notifies the preprocessor to include the contents of the input/output stream header file <iostream> in the program
We can use the Escape Sequence to format the Displayed Text.

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We can put comment on our programs using

// to comment a single line
// this progrm is written by mohamed El desouki

/*
Mulitple Lines
*/ to comment multiple lines

/* This program is written by ahmad

On Monday */
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Interacting With User: Comments

Example 1

Write a program to find the Area of a rectangle

The area of the Rectangle are given by the following formula:

Area = Rect Length * Rect Width.

Input :

Rectangle Length , Rectangle Width.

Processing :

Area = Rect Length * Rect Width.

Output :
Print Out The area.

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Central Processing Unit and Main Memory

C++ Programming: From Problem Analysis to Program Design, Fifth Edition
22

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Interacting With User: Accept Input From User
In C++ , we use Cin >> Variable; To accept an input from the user.
To use Cin >>, we must use #include <iostream> ;
#include <iostream> notifies the preprocessor to include in the program the contents of the input/output stream header file <iostream>.

A variable is a location in the computer’s memory where a value can be stored for use by a program.
All variables must be declared with a name and a data type before they can be used in a program.

Declaration

DataType Identifier;

Int width ;
Float salary ;

C++ Data Types

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char
Character or small integer.
1byte
signed: -128 to 127unsigned: 0 to 255
int
Integer.
4bytes
signed: -2147483648 to 2147483647unsigned: 0 to 4294967295
short int (short)
Short Integer.
2bytes
signed: -32768 to 32767unsigned: 0 to 65535
long int (long)
Long integer.
4bytes
signed: -2147483648 to 2147483647unsigned: 0 to 4294967295
bool
Boolean value. It can take one of two values: true or false.
1byte
true or false
float
Floating point number.
4bytes
+/- 3.4e +/- 38 (~7 digits)
double
Double precision floating point number.
8bytes
+/- 1.7e +/- 308 (~15 digits)
long double
Long double precision floating point number.
8bytes
+/- 1.7e +/- 308 (~15 digits)

Working With Variable
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Int length ;

Int width;
Int area;

Cin>>Length;

Cin>>width;

Area = Length * width ;

Length
Width
area
5
10
50

Example 2

Write a program to find the perimeter and area of a square

Declaring & Initializing Variables

Initialization means to give a variable an initial value.

Variables can be initialized when declared:

int first=13, second=10;
char ch=' ';
double x=12.6;

All variables must be initialized before they are used in an arithmetic operatation

But not necessarily during declaration

Rules on Variable Names

DO NOT use reserved words as variable names
(e.g. if, else, int, float, case, for, …).

The first character has to be a letter or underscore. It can not be a numeric digit.

The second and the other characters of the name can be any letter, any number, or an underscore “_”.

Examples

Some valid names:
my_name, m113_1, salary, bluemoon , _at

Some invalid names:
my name, my-name , 1stmonth , salary! , guns&roses ,

Frequently used data types

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Data Types
Bytes Used
int
4 Bytes
short
2 Bytes
double
8 Bytes
unsigned
4 Bytes
• Float
• 4 Bytes
• Double
• 8 Bytes
• Char
• 1 Byte
The data type unsigned is used to represent positive integers.
float and double data types for storing real numbers.

The float data type has a precision of seven digits

This means after the decimal point you can have seven digits

Example: 3.14159 534.322344 0.1234567
The double data type has a precision of fifteen digits

Example :

-3738.7878787878 3.141592653589790
0.123456789123456

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We can use Scientific Notation to represent real numbers that are very large or very small in value.
The letters e or E is used to represent times 10 to the power.

Example:

1.23 x 10 5 is represented as 1.23e5 or 1.23e+5 or 1.23E5
1 x 10 -9 is represented as 1e-9

Frequently used data types

Arithmetic Operations
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Parentheses are used in C++ expressions in the same manner as in algebraic expressions.

For example, to multiply a times the quantity b + c

we write a * ( b + c ).

There is no arithmetic operator for exponentiation in C++,
so x2 is represented as x * x.

Precedence of arithmetic operations

For example,

2 + 3 * 5 and (2 + 3) * 5

both have different meanings

Precedence of arithmetic operations

Example :

? = 1 + 2 * (3 + 4)

Evaluated as 1 + (2 * (3+4)) and the result is 15
? = 5 * 2 + 9 % 4
Evaluated as (5*2) + (9 % 4) and the result is 11
? = 5 * 2 % ( 7 – 4)
Evaluated as (5 * 2) % (7 – 4) and the result is 1

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Precedence of arithmetic operations

Data Type of an Arithmetic Expression

Data type of an expression depends on the type of its operands
Data type conversion is done by the compiler

If operators are *, /, +, or – , then the type of the result will be:

integer, if all operands are integer.
Int A , B;
A+ B  Integer.
float, If at least one operand is float and there is no double
Int A ; Float B;
A + B  Float.
double, if at least one operand is double
Int A ; Float B; Double C;
A + B + C  double.

Data Type of an Arithmetic Expression

Example
int * int;

int + float;

Int + double / float;

int – double;

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result int
result float
result double
result double

Data Type of an Arithmetic Expression

The data type of the target variable is also important
If the result is a real number and the target variable is declared as integer, only the integer part of the result will be kept, and decimal part will be lost.

Example

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The result is calculated as 16.66667

But avg will be 16

int avg;
float sum=100.0, cnt = 6.0;
avg = sum / cnt;

Data Type of an Arithmetic Expression

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The result of the division will be 16
avg will be 16.0
• int sum=100, cnt = 6;
• avg = sum / cnt;
• Only the integer part of the result will be considered if two operands are integer Even when the target variable is float

Type Casting

int main()
{
int i=5, j=3;
float div;
div= i/j;
cout<< div;
}
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The div will be 1.0 and this is not write
• int main()
• {
• int i=5, j=3;
• float div;
• div=(float) i/j;
• cout<< div;
• }
Type cast: tells the compiler to treat i as a float

After type casting , The div will be 1.66667

Increment and Decrement Operators

Increment operator: increment variable by 1
Pre-increment: ++variable
Post-increment: variable++

Decrement operator: decrement variable by 1

Pre-decrement: --variable
Post-decrement: variable --
• Examples :
++K , K++  k= K+1
--K , K--  K= K-1

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Increment and Decrement Operators

If the value produced by ++ or – – is not used in an expression, it does not matter whether it is a pre or a post increment (or decrement).

When ++ (or – –) is used before the variable name, the computer first increments (or decrements) the value of the variable and then uses its new value to evaluate the expression.

When ++ (or – –) is used after the variable name, the computer uses the current value of the variable to evaluate the expression, and then it increments (or decrements) the value of the variable.

There is a difference between the following

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x = 5;
Cout << ++x;
x = 5;
Cout << x++;

special assignment statements

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C++ has special assignment statements called compound assignments
+= , -= , *= , /= , %=
Example:
X +=5 ; means x = x + 5;
x *=y; means x = x * y;
x /=y; means x = x / y;

Control Statements

• Normally, statements in a program are executed one after the other in the order in which they’re written.
• This is called sequential execution.
• There are control statements enable you to specify that the next statement to be executed may be other than the next one in sequence.
• This is called transfer of control.
• The control statements are categorized in almost two groups:
• Selection control statements
• Repetition control statements

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1
2
3
6
4
5
7
9
8

Sequential Execution

Transfer of Control

Selection statements are used to choose among alternative courses of action.

For example, suppose the passing mark on an exam is 60. The pseudocode statement
If student’s marks is greater than or equal to 60 Then Print “Passed”
Selection Statements : If Statement

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if ( Expression) action statement ;
if ( Expression) {
action statement 1 ;
action statement 2 ;
.
.
action statement n ;
}
In C++ , The syntax for the If statement
if ( grade >= 60 ) cout <<"Passed\n“;
The Expression can be any valid expression including a relational expression and even arithmetic expression

In case of using arithmetic expressions , a non-zero value is considered to be true, whereas a 0 is considered to be false

Relational Expression and Relational Operators

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Operator
Means
==
Equal To
!=
Not Equal To
<
Less Than
<=
Less Than or Equal To
>
Greater Than
>=
Greater Than or Equal To
Relational expression is an expression which compares 2 operands and returns a TRUE or FALSE answer.
Example : a >= b , a == c , a >= 99 , ‘A’ > ‘a’

Relational expressions are used to test the conditions in selection, and looping statements.

Example : write a program that accept an integer from the user and in case this integer is even print out the following message
“This number is even “ .

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Selection Statements : If Statement

• The IF…Else selection statement allows you to specify that there is a course of actions are to be performed when the condition is true and another course of actions will be executed when the condition is false.
• For example, the pseudocode statement
• If student’s mark is greater than or equal to 60Print “Passed”elsePrint “Failed”
Selection Statements : If .. Else Statement

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if ( Expression) action statement ;
Else
action statement ;
if ( Expression) {
action statements 1 ;
.
action statement n ;
}
Else
{
action statements 1 ;
.
action statement n ;
}
In C++ , The syntax for the If…Else statement
if ( grade >= 60 ) cout <<"Passed\n“;
Else
cout <<“Failed\n”

Example : write a program that accept an integer from the user and

print out whether it is Positive or Negative number.
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Selection Statements : If – else Statement

Nested If

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Nested If : means to write an if statement within another if statement.

Example : write a program that accept an integer number from the user ,

in case the number is Positive , check and print out whether it is Even or Odd number.

int main()

{
int number;
cout <<"Please Enter any number \n";
cin >>number;

if ( number >=0)

if (number % 2 == 0)
cout <<" This is an Even number \n";
else
cout <<"This is an Odd number \n \n";

}

IF – Else IF statement

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• For example, write a program that ask the user to Enter 2 numbers and print out whether they are equal or there is one which is greater than the other.
int main()
{
int num1, num2;
cout <<"Enter Number 1 , Number2 \n";
cin >>num1>>num2;

if ( num1 == num2 )
cout << "Both Are Equal \n";
else if (num1 > num2 )
cout <<"Number 1 is greater than number 2 \n";
else
cout <<"Number 2 is greater than number 1 \n";

}

IF – Else IF

54
• For example, the following code will print
• A for exam grades greater than or equal to 90,
• B for grades greater than or equal to 80,
• C for grades greater than or equal to 70,
• D for grades greater than or equal to 60, and
• F for all other grades.
• if ( grade >= 90 ) cout << "A\n“ ;else if ( grade >= 80 ) cout << "B\n”;else if ( grade >= 70 ) cout << "C\n”;else if ( grade >= 60 ) cout << "D\n”;else cout << "F\n“ ;

Combining more than one condition
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Operator
Means
Description
&&
And
The Expression Value Is true If and Only IF both Conditions are true
• To combine more than one condition we use the logical operators.

Example : check whether num1 is between 0 and 100

IF ( (num1 >= 0) && (num1 <=100) )
Cout <<“The Number Is between 1 and 100” ;
Else
Cout <<“ The Number Is Larger Than 100”;

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• Example, print out the student grade according to the following formulas:
• A for exam marks greater than or equal 90 and less than or equal 100 ,
• B for exam marks greater than or equal 80 and less than 90 ,
• C for exam marks than or equal to 70 and less than 80 ,
• D for exam marks than or equal to 60, and less than 70 ,
• F for all other marks.
if ( marks >= 90 && marks <= 100) cout << "A\n“ ;else if (marks >= 80 && marks <90 ) cout << "B\n”;else if (marks >= 70 && marks <80 ) cout << "C\n”;else if (marks >= 60 && marks <70 ) cout << "D\n”;else cout << "F\n“ ;
Combining more than one condition

Example : A company insures its Employees in the following cases:
Employee is married.
Employee is an Single male above 30 years of age.
Employee is an Single female above 25 years of age.

Conditions :

• Marital status = ‘M’; OR
• Marital Status =‘S’ and Sex=‘M’ and Age >30 OR
• Marital Status =‘S’ and Sex=‘F’ and Age >25

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Selection statements: Switch Statement.

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The switch control statement that allows us to make a decision from the number of choices
Switch (Expression )
{
case constant 1 :
Action statements;
break ;
case constant 2 :
Action statements;
break ;
case constant 3 :
Action statements;
break ;
default :
Action statements;
}
Expression It could be an integer constant like 1, 2 or 3, or an expression that evaluates to an integer .
Constant : is a specific value.

Switch (10);

Int i ;

Switch (i);

switch ( i + j * k )

switch ( 23 + 45 % 4 * k )
Switch (10.0);

float i ;

Switch (i);

switch ( i + j * k )

switch ( 23 + 45 % 4 * k )

Case 50:

Case 40 +10;

Case >= 50;
Case a+ b;

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60
int i;
Cin>>I;
switch ( i )
{
case 10 :
Cout << "I am in case 1 \n“ ;
break ;
case 20 :
Cout << "I am in case 2 \n“ ;
break ;
case 30 :
Cout << "I am in case 3 \n“ ;
break ;
default :
Cout << "I am in default \n“ ;
}
char ch = 'x' ;

switch ( ch )
{
case 'v' :
Cout<< "I am in case v \n“ ;
break ;
case 'a' :
Cout<< "I am in case a \n“ ;
break ;
case 'x' :
Cout<< "I am in case x \n” ;
break ;
default :
Cout<< "I am in default \n„ ;
}
Expression Possible Forms

switch ( i + j * k )

switch ( 23 + 45 % 4 * k )

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switch (grade)
{
case 90 :
cout <<"You Got A \n"; break;

case 80 :
cout <<"You Got B \n"; break;

case 70 :

cout <<"You Got C \n"; break;

case 60 :

cout <<"You Got D \n"; break;

default :

cout <<" Sorry , You Got F \n";
}
if ( marks >= 90 && marks <= 100) cout << "A\n“ ;else if (marks >= 80 && marks <90 ) cout << "B\n”;else if (marks >= 70 && marks <80 ) cout << "C\n”;else if (marks >= 60 && marks <70 ) cout << "D\n”;else cout << "F\n“ ;

Switch Versus IF – Else IF

There are some things that you simply cannot do with a switch. These are:
A float expression cannot be tested using a switch
Cases can never have variable expressions (for example it is wrong to say case a +3 : )
Multiple cases cannot use same expressions.

switch works faster than an equivalent IF - Else ladder.

Control Statements : Repetition statements
Some times we need to repeat a specific course of actions either a specified number of times or until a particular condition is being satisfied.

For example :

To calculate the Average grade for 10 students ,
To calculate the bonus for 10 employees or
To sum the input numbers from the user as long as he/she enters positive numbers.

There are three methods by way of which we can repeat a part of a program. They are:

(a) Using a while statement
(b) Using a do-while statement
(C) Using a for statement

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1- The While Loop

1- loop counter is any numeric variable ( int , float ,….).
2- when using a counter , the while loop is called
counter –controlled loop.
3- The initial value of the loop counter is up to you,
but you have to increment it to avoid endless loops.
While ( continuation condition)
{

Action statement 1 ;
Action statement 2 ;
.
.
Action statement n ;
}

1- The While Loop

The condition being tested may be relational, logical or even numeric expression :

while ( i <= 10 )
while ( i >= 10 && j <= 15 )
While (3) , While (3 + 5)

• Example : Write a program that calculates and prints out the Average grade for 6 students .

int counter = 1;

int grade=0 , sum=0;
while (counter <=6)
{
cout <<"Enter grade for student no " << counter <<"\n";
cin >>grade;
sum += grade;
counter ++;
}
cout <<"Average Grade is " << sum/counter <<"\n";

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1- The While Loop

• Example : Write a program To print out the sum of the numbers entered from the user as long as he/she enters positive numbers.

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• int number=0 , sum=0;
• while (number >= 0)
• {
• cout <<" Enter Positive numbers to sum \n";
• cin>>number;
• sum += number;
• }
• Cout <<“ sum = “ << sum <<“\n”;
1- The While Loop

• Example : Write a program To print out the sum of the numbers entered from the user as long as he/she enters positive numbers.

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• int number=0 , sum=0;
• cout <<" Enter Positive numbers to sum \n";
• cin>>number;
• while (1)
• {
• sum += number;
• cout <<" Enter Positive numbers to sum \n";
• cin>>number;
• If (number < 0)
• break;
• }
1- The While Loop

• Example : Write a program that calculates and prints out the Average grade for 5 students or ends the program by entering -1.

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• int grade=0, counter =1, sum=0;
• cout <<" Enter 5 grades or -1 To Exit \n";
• while (counter <=5 && grade !=-1)
• {
• cin>>grade;
• sum += grade;
• counter ++;
• }
• cout <<"The sum of grades is " << sum <<"\n";
1- The While Loop

2- The do-while Loop

1- loop counter is any numeric variable ( int , float ,….).

2- The initial value of the loop counter is up to you,
but you have to increment it to avoid endless loops.
3- The Loop Body is Executed at least one Time.

2- The do-while Loop

The condition being tested may be relational, logical or even numeric expression :

while ( i <= 10 )
while ( i >= 10 && j <= 15 )
While (3) , While (3 + 5)

• Example : Write a program that calculates and prints out the Average grade for 6 students .

int counter = 1;

int grade=0 , sum=0;
do
{
cout <<"Enter grade for student no " << counter <<"\n";
cin >>grade;
sum += grade;
counter ++;
}
while (counter <=6) ;

cout <<"Average Grade is " << sum/counter <<"\n";

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2- The do-While Loop

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2- The do-While Loop

Control Statements : Repetition statements
Some times we need to repeat a specific course of actions either a specified number of times or until a particular condition is being satisfied.

For example :

To calculate the Average grade for 10 students ,
To calculate the bonus for 10 employees or
To sum the input numbers from the user as long as he/she enters positive numbers.

There are three methods by way of which we can repeat a part of a program. They are:

(a) Using a while statement
(b) Using a do-while statement
(C) Using a for statement

3- The For Loop.

For Loop is probably the most popular looping instruction.

general form of for statement is

• The for allows us to specify three things about a loop in a single line:

• (a) Setting a loop counter to an initial value.
• (b) testing the loop counter to detect whether its value reached the number
• of repetitions desired.
• (c) increasing the value of loop counter each time the program segment
• within the loop has been executed.

• Example : Write a program that calculates and prints out the Average grade for 6 students .

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• int grade=0, sum=0;
• for (int counter =1 ; counter <=6 ; counter ++)
• {
• cout <<"Enter Grade \n";
• cin>>grade;
• sum += grade;
• }
• cout <<"The Average grades is “ << sum/6 <<"\n";
3- The For Loop.
int counter = 1;
int grade=0 , sum=0;
while (counter <=6)
{
cout <<"Enter grade for student \n“ ;
cin >>grade;
sum += grade;
counter ++;
}
cout <<"Average Grade is "
<< sum/6 <<"\n";

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• Example : Write a program that prints out numbers from 0 to 10;

• for (int i= 0 ; i <=10 ; i++)

• cout << i << "\n“;
• Example : Write a program that prints out the even numbers from 2 to 20;
• for (int i = 2 ; i <=20 ; i+=2 )
• cout << i << "\n“;
3- The For Loop.
• Example : Write a program that prints out numbers from 0 to 10 in descending order;
• for (int i = 10 ; i >=0 ; i-- )
• cout << i << "\n“;

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• Example : Write a program that accepts 10 numbers from the user and prints out the sum of even numbers and the sum of odd numbers.
3- The For Loop.

79
int i = 1 ;
for ( ; i <= 10 ; i + + )
cout<< i ;
int i = 1 ;
for ( ; i <= 10 ; )
{
cout<< i ;
i ++;
}
int i ;
for ( i = 0 ; i++ < 10 ; )
cout<< i ;
int i ;
for ( i = 0 ; ++ i < 10 ; )
cout<< i ;
3- The For Loop.

• Example : Write a program that calculates the Factorial for any given positive number.
• Ex : Factorial (5) = 5 * 4 * 3 * 2 * 1

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• int number, factorial=1;
• cout <<"Enter a positive number\n";
• cin >> number;
• if (number < 0 )
• cout <<" Enter Positive Numbers only\n";
• else
• for (int i= 1 ; I <=number ; i++)
• factorial = factorial * i;
• cout <<" Factorila = “ << factorial <<"\n";
3- The For Loop.

Nested Loops

• Example : Write a program that calculates the Factorial for numbers from 1 to 10;

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• for ( int number=1; number<=10 ; number++)
• {
• for ( int i= 1 ; i <=number ; i++)
• {
• factorial = factorial * i ;
• }
• cout <<" Factorila of " << number <<"=" << factorial <<"\n";
• }

*
**
***
****
*****
******

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• Example : Write a program that prints out the following pattern.
Nested Loops
• for (int i = 1; i <= 5; i++)
• {
• for (int j = 1; j <= i ; j++)
• cout << "*";
• cout << endl;
• }

Functions

Most computer programs that solve real-world problems include hundreds and even thousands of lines.

Experience has shown that the best way to develop and maintain a large program is to construct it from smaller pieces or modules, each of which is more manageable than the original program.

This technique is called divide and conquer.

A Function : is a self-contained block of statements that perform a specific task.

using a function is something like hiring a person to do a specific job for you.

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84

Task 1

Task 2
Task 3
Task 4
Function ( )
Function ( )
Function ( )
Function ( )
In Real Life
In Programming

Why to use Functions ?
Functions allows to write more manageable units of code.
Writing functions avoids rewriting the same code over and over.
Easy maintenance for programs.

Important Tips

1- Don’t try to cram the entire logic in one function. It is a very bad style of programming.

2- Instead, break a program into small units and write functions for each of these isolated subdivisions.

3- Don’t hesitate to write functions that are called only once.

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86

Task 1

Task 2
Task 3
Task 4
Get_Marks( )
Calc_sum( )
Calc_Average ( )
Print_out ( )
Calculate and print out The sum and the Average of 3 student marks.

Functions

87
Function Definition

return-value-type function-name( parameter-list )

{
Lines of code to be
executed
…
…
…
(Body)
}

Parameter-List : Is a list of data values supplied from the calling program as input to the function. It is Optional
return-value-type:
Is the data type for the returned value from the function to the calling program. It is Mandatory, if no returned value expected , we use keyword Void.

Function Types

• Built in Functions (Ready Made).
For Example : Math Library Functions <cmath> Like
88

Built in Functions

int abs (int number) ;

double pow (double base, double exponent) ;

Double floor (double number);

Double sqrt (double number);

89
To correctly use the built in functions we must know well its header (prortotype).
return-value-type function-name( parameter-list )

90
• #include <iostream>
• #include <cmath>
• using namespace std;
• int main ( )
• {
• int i = -5 ;
• double x = 5.0;
• double y = 2.0;
• double z = 5.21;
• cout << "The absolute value of i is " << abs (i) << "\n \n";
• cout << "The power of x to the power y is " << pow (x,y) << "\n \n";
• cout << "The Floor for Z is " << floor (z) <<"\n \n";
• cout << "The Ceil for Z is " << ceil (z) <<"\n \n";
• }

Function Types

91
• Working with user defined functions is done in three steps :
1- Function declaration (Prototype , in C++ written before Main ( ) ).
2- Function Definition (Body, in C++ written After Main ( ) ).
3- Invoking Function (Calling, From The Main ( ) ).

Building Functions
92
1- Function Declaration (Written before The main( ) )

return-value-type function-name( Formal parameter-list )

2- Function Definition (Written after The main( ) )

return-value-type function-name( Formal parameter-list )

{
Lines of code to be
executed
}

3- Invoking Function ( From The main( ) )

Function name ( Actual Parameter- List );

Formal Parameter-List : Is a list of input parameters with their data types .

Int abs ( int x );
Actual Parameter-List : Is a list of input parameters without their data types .
Cout << abs ( i );

User-Defined Functions
Value-returning functions: have a return type
Return a value of a specific data type using the return statement
the returned value can be used in one of the following scenarios:
Save the value for further calculation
Int result;
Result = sum ( x , y );

Use the value in some calculation

Result = sum(x , y) /2;

Print the value

Cout << sum(x , y);

Void functions: do not have a return type

Do not use a return statement to return a value

Flow of Execution

Execution always begins at the first statement in the function main

Other functions are executed only when they are called

Function prototypes appear before any function definition
The compiler translates these first

The compiler can then correctly translate a function call

Flow of Execution (cont'd.)
A function call results in transfer of control to the first statement in the body of the called function

After the last statement of a function is executed, control is passed back to the point immediately following the function call

A value-returning function returns a value

After executing the function the returned value replaces the function call statement

For Example : write a program that ask the user to Enter 2 integer numbers and print out the larger of them.
96
• int larger (int num1 , int num2);
• int main ()
• {
• int n1 , n2 , result;
• cout <<"Please Enter 2 integer numbers \n";
• cin >>n1 >> n2;
• result = larger(n1,n2);
• cout <<" The Larger number is " << result<<"\n";
• }
• int larger (int num1 , int num2)
• {
• int max;
• if (num1 >= num2)
• max = num1;
• else
• max = num2;
• return max;
• }

For Example: Write a program to calculate the Area and volume for a sphere.

The area of sphere = 4 * PI * Radius * Radius .

The Volume of sphere = 4/3 * PI * Radius * Radius * Radius .
Note : PI = 3.14

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98
• For Example : write a program that ask the user to Enter 3 integer numbers and print out their sum and Average.
• int sum (int num1 , int num2, int num3);
• float average (int num1,int num2, int num3 );
• int main ()
• {
• int n1 , n2 , n3 ;
• cout <<"Please Enter 3 integer numbers \n";
• cin >>n1 >> n2 >> n3;
• cout <<" The sum of the 3 number is " << sum (n1, n2,n3) <<"\n";
• cout <<" The average of the 3 number is " << average (n1, n2,n3) <<"\n";
• }
• int sum (int num1 , int num2, int num3)
• {
• return num1+num2+num3;
• }
• float average (int num1, int num2, int num3 )
• {
• return sum (num1 , num2 , num3)/3;
• }

99
Function Parameter’s Default Value
• int sum (int num1 , int num2, int num3 = 90);
• int main( )
• {
• int n1 , n2 ;
• cout <<"Please Enter 3 integer numbers \n";
• cin >>n1 >> n2 ;
• cout <<" The sum of the 3 number is " << sum (n1, n2) <<"\n";
• }
• int sum (int num1 , int num2, int num3 = 90)
• {
• return num1+ num2+ num3;
• }

Function Parameters Types

100
Value parameter: Reference parameter:
The value parameter has its own copy of the data
During program execution, The value parameter manipulates the data stored in its own memory space. So , the actual parameter not Affected with any change.

• void swap( int x, int y )
• {
• int temp;
• temp= x;
• x = y;
• x = temp;
• }

x

y

Temp

10
20

Reference parameter:

A reference parameter stores the address of the corresponding actual parameter
During program execution to manipulate data, The address stored in the reference parameter directs it to the memory space of the corresponding actual parameter
Reference parameters are useful in three situations:
Returning more than one value
Changing the actual parameter
When passing the address would save memory space and time

101
Function Parameters Types

102
Function Parameters Types
• void swap( int &x, int &y )
• {
• int temp;
• temp= x;
• x = y;
• x = temp;
• }

Scope of a variable

scope is the context within a program in which a variable is valid and can be used.

Local variable: declared within a function (or block)

can be accessible only within the function or from declaration to the end of the block.
Within nested blocks if no variable with same name exists.
103
• int main ( )
• {
• {
• Int x ;
• }
• }
• int sum (int x , int y )
• {
• int result ;
• result = x + y;
• return result;
• }

Local

Scope of a variable
Global variable: declared outside of every function definition.
Can be accessed from any function that has no local variables with the same name. In case the function has a local variable with the same name as the global variable ,

104
• Int z ;
• int main ( )
• {
• {
• }
• }
• int sum (int x , int y )
• {
• }

Global

105
• int x = 100 ;
• int main ( )
• {
• int x= 10;
• int y = 50;
• cout << " Global X" << ::x << " Main X" << x << " " << y;
• {
• int z , x ;
• z=100;
• y=100;
• x= 250;
• cout <<" inner block " << x ;
• }
• }
• Scope of a variable

Global

Local

Local

106
Using global variables causes side effects

A function that uses global variables is not independent

If more than one function uses the same global variable and something goes wrong ,
It is difficult to find what went wrong and where Problems caused in one area of the program may appear to be from another area.
To prevent the global variable to be modified use the Const Keyword.

Const float pi = 3.14;

Scope of a variable

Static and Automatic Variables

Automatic variable:

memory is allocated at block entry and de-allocated at block exit

By default, variables declared within a block are automatic variables

107
• int issue_ticket (int x , int y )
• {
• int ticket_no = 0;
• cout <<"Flight No : " <<flight_no <<"\n";
• cout <<"Ticket no : " << ++ ticket_no <<"\n";
• cout <<"Issued For: " << pname <<"\n \n \n";
• }
0
Ticket No
1
Ticket No

Static and Automatic Variables
Automatic variable:

memory is allocated at block entry and de-allocated at block exit

By default, variables declared within a block are automatic variables

Static variable:

memory remains allocated as long as the program executes
Variables declared outside of any block are static variables
Declare a static variable within a block by using the reserved word static .

Static int x;

108

Arrays

Array : is a collection of fixed number of elements, wherein all of elements have same data type.

Array Basics:

Consecutive group of memory locations that all have the same type.

The collection of data is indexed, or numbered, and at starts at 0 and The highest element index is one less than the total number of elements in the array.

One-dimensional array:

elements are arranged in list form.
Multi-dimensional array:
elements are arranged in tabular form.

Syntax for declaring a one-dimensional array:

Datatype ArrayName [ArraySize] ;

ArraySize: any positive integer or constant variable.

110
• Example:
• int num[5];

Arrays

• Example: const int size = 5 ;
• int num[size];
num

Accessing array Elements
Arrayname [element index].

Arrays

• Example: int list[10];

• list[5] = 34;

• Cout << list [5];

112
Array Initialization
Consider the declaration

int list[10]; //array of size 10

After declaring the array you can use the For .. Loop to initialize it with values submmited by the user.

Using for loops to access array elements:

for (int i = 0; i < 10; i++)
//process list[i]
Example:

for (int i = 0; i < 10; i++)

cin >> list[i];

Example : Write a program that ask the user to enter 10 Employee salaries and store them , then add a bonus of 10 % for each employee and print out the average salary value.
113

Arrays can be initialized during declaration

In this case, it is not necessary to specify the size of the array
Size determined by the number of initial values in the braces

Example 1: int Items[] = {12, 32, 16, 23, 45};

Example 2: int items [10] = { 0 };

Example 3: int items [10] = { 5, 7, 10 };

114
Array Initialization

int Arr1[5];

int Arr2 [ 5 ] ;

Arr1 = Arr2 ;

115
Array Initialization

116
Array as a Parameter to Function
Arrays are passed by reference only
The symbol & is not used when declaring an array as a formal parameter
The size of the array is usually passed as a parameter to the function.

Float calc_Average ( Float marks [ ] , int size )

{
float sum =0 ;

for (int I =0 ; I <size ; I ++)

Sum += marks [ I ] ;

return sum / size;
}
• We may add keyword const before array name to
• Prevent the function from modifying the array elements.
Float calc_Average ( const Float marks [ ] , int size )

117
bool find_Item( int list[ ] , int searcheditem , int size)
{
int indx;
bool found = false;

for ( indx = 0 ; indx < size ; indx++)

if (list[indx] == searcheditem)
{
found =true ;
break ;
}
return found;
}
Example : Write a program that uses a function to search for an item within an array.

Two Dimensional Array
Used when data is provided in a table form.
For Example , to store 4 Marks for 6 students.

118
• M3
• M2

M 1

Student 1

Student 2
Student 3
Student 4
Student 5
Student 6

119
Two dimensional Array declaration

Datatype ArrayName [ Rows] [Columns] ;

Example :

Float marks [6] [4] ;

1
2
3
4
5
0
1
2
3
20
marks [4][2]= 20 ;
0

120
Two dimensional Array Initialization
Consider the declaration

float marks[6][4];

After declaring the array you can use the For .. Loop to initialize it with values submmited by the user.

Using 2 nested for loops to access array elements:

for (int row = 0; row < 6; row++)
for (int col = 0; col < 4; col++)
cin >> marks[ row ][col];

Two dimensional Arrays can be initialized during declaration

Example 1: float marks[4][3] = {{20,30,35},
{40,45,65},
{60,65,75},
{80,65,45}};

121
Two dimensional Array Initialization

122
• Example : Write a program that build a matrix of 5 rows and 3 columns . As the use to enter the values for all the matrix items , print out the sum of all matrix items and print out the sum of the diagonal items.

void printMatrix( int matrix[ ][4], int Rows)
{
int row, col;
for (row = 0; row < Rows ; row++)
{
for (col = 0; col < 4; col++)
cout << setw(5) << matrix [row] [col] ;
}
cout <<“\n” ;
}
123
when declaring a two-dimensional array as a formal parameter, you can omit the size of the first dimension, but not the second;
that is, you must specify the number of columns.
Two dimensional Array as a Parameter to Function

Struct

Struct: collection of a fixed number of components (members), accessed by name
Members may be of different types.
For Example : to store a student record which includes different data items like (student_no , Fname, Lname , Total_Marks , GPA , …….).

Syntax for Defining Struct is :

124
Struct struct_name
{
Datatype identifier 1;
Datatype identifier 2;
.
.
.
Datatype identifier n;
} ;

For Example : To store an Employee data like ( emp_no , fname , lname , salary , bonus , net_salary );

125
Struct Employee
{
int emp_no ;
string fname ;
string lname;
float salary;
float bonus ;
float net_salary;
} ;
Struct

Once , a new struct is defined , we can use it as any other data type.

126
struct Employee
{
int emp_no ;
string fname ;
string lname;
float salary;
float bonus ;
float net_salary;
} ;

int main ()

{

Employee emp1 , emp 2;

}
Emp 1
Emp_no :
Fname :
Lname :
Salary :
Bonus :
Net_salary :
Emp 2
Emp_no :
Fname :
Lname :
Salary :
Bonus :
Net_salary :
Struct

To Access the Memebers of the struct , use the . Operator

127
struct Employee
{
int emp_no ;
string fname ;
string lname;
float salary;
float bonus ;
float net_salary;
} ;

int main ()

{
Employee emp1;
emp1.emp_no = 12;
emp1.fname="Ahmed";
emp1.lname="Ali";
emp1.salary=3000;
emp1.bonus=500;
emp1.net_salary= emp1.salary + emp1.bonus;
}
Emp 1
Emp_no :
Fname :
Lname :
Salary :
Bonus :
Net_salary :
12
Ahmed
Ali
3000
500
3500

Assignment and Comparison
Value of one struct variable can be assigned to another struct variable of the same type using an assignment statement
Example :
Employee emp1 , emp2 ;
emp2 = emp1;
copies the contents of emp1 into emp2 ;

128
• Compare struct variables member-wise
• No aggregate relational operations allowed
• To compare the values of emp1 and emp2

if ( emp1.emp_no == emp2.emp_no &&

emp1.fname == emp2.fname && emp1.salary == emp2.salary )
{

}

struct Variables and Functions

A struct variable can be passed as a parameter by value or by reference.
A function can return a value of type struct
129
struct distance_type
{
Int feet ;
float inches;
};

distance_type Add_distances (distance_type d1 , distance_type d2 );

int main ()

{
}
distance_type Add_distances (distance_type d1 , distance_type d2 )
{
distance_type result;
result.feet = d1.feet + d2.feet;
result.inches = d2.inches + d2.inches ;
return result;
}

130
Arrays in structs
struct Student
{
int student_no ;
string sname ;
float GPA;
float marks[3];
} ;

int main ()
{
Student s1;
s1.student_no = 120;
s1.sname="Ahmed Ibrahim";
s1.GPA= 3.56;
s1.marks[0] = 80;
s1.marks[1] = 70;
s1.marks[2] = 90;
}

131
structs in Arrays
struct Employee
{
int emp_no ;
string fname ;
string lname;
float salary;
float bonus ;
float net_salary;
} ;

int main ()
{
Employee arr[5];
arr[0].emp_no = 12;
arr[0].fname="Ahmed";
arr[0].lname="Ali";
arr[0].salary=3000;
arr[0].bonus=500;
arr[0].net_salary= arr[0].salary + arr[0].bonus;
}

structs within a struct

132



Revision
Write a program that used to manage The HR data of a department that has a team of 5 employees . The employee data like ( eno , ename , job ,salary , bonus). The program should have

• Function to accept the data of employees and automatically set the salary according to the following formulas In case the
job = ‘Manager’  salary = 5000
job = ‘Engineer’  salary = 3000
job = ‘Clerck’  salary = 2000
Otherwise  salary = 1000

• 2. Function to set the bonus value for a specific employee

• according to specific percent.

3. Function to print out the data of all employees.

133