The document provides an introduction and overview of conditions and loops in C++ programming. It covers arithmetic operations, relational expressions, if/else statements, while loops, do-while loops, and for loops. Examples are given for each concept to demonstrate their syntax and usage. Key topics covered include operators, increment/decrement, if/elseif statements, comparing values, and using loops to repeat blocks of code multiple times.

1. Introduction to
programming
with
C++
Day 2 (Conditions & Loops)
By : eng / Khaled ahmed

2. • Programming course :
• (C++ , problem solving) :
1- Introduction
2-Conditions & Loops
3-Arrays
4-Strings
5-Functions
6- struct & review
7- OOP in C++
8- INHERITANCE IN C++
9-files ( input & output )
10-General Review

3. ARITHMETIC OPERATIONS 3
▪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.

4. PRECEDENCE OF ARITHMETIC OPERATIONS
? = 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
4

5. 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
5

6. SPECIAL ASSIGNMENT STATEMENTS
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;
6

7. SELECTION STATEMENTS : IF
STATEMENT
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”
7

8. 8
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 <<"Passedn“;

9. RELATIONAL EXPRESSION AND
RELATIONAL OPERATORS
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.
9
Operator Means
== Equal To
!= Not Equal To
< Less Than
<= Less Than or Equal To
> Greater Than
>= Greater Than or Equal To

10. 10
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 <<"Passedn“;
Else
cout <<“Failedn”

11. IF – ELSE IF STATEMENT 11
• 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";
}

12. COMBINING MORE THAN ONE
CONDITION
12
Operator Means Description
&& And The Expression Value Is true If and Only IF both Conditions
are true
|| OR The Expression Value Is true If one Condition Is True
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”;


13. 13
Loops
■ Repetition is referred to the ability of
repeating a statement or a set of
statements as many times this is
necessary.

14. 14
Loops
while()
do – while()
for( ; ; )

15. 15
The while() Loop
while (<Condition>)
<Loop body> ;
Con
ditio
n
Loop
Body
true
false

16. 16
#include <iostream>
using namespace std;
int main()
{
cout << ” * n”;
cout << ” *** n”;
cout << ”*****n”;
cout << ” * n”;
cout << ” * n”;
cout << endl;
}
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*

17. 17
i
Variable
#include <iostream>
using namespace std;
int main()
{
int i = 1;
while (i <= 4)
{
cout << ” * n”;
cout << ” *** n”;
cout << ”*****n”;
cout << ” * n”;
cout << ” * n”;
cout << endl;
i++;
}
}
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
true
false
1
2
3
4
5
Screen

18. 18
i
Variable
#include <iostream>
using namespace std;
int main()
{
int i = 1;
while (i < 11)
{
i += 3;
cout << i << endl;
}
}
4
7
10
13
1
4
7
10
13
Screen

19. 19
Examples
int main()
{
int i = 1;
while (i<=5)
{
cout << i << ’ ’;
i++;
}
}
int main()
{
int i = 1;
while (i<=5)
{
cout << ’i’ << ’ ’;
++i;
}
}
1 2 3 4 5
i i i i i

20. 20
More Examples
int main()
{
int i = 1;
while (i<=5)
cout << i << ’ ’;
i++;
}
int main()
{
int i = 1;
while (i<=5)
cout << i++ << ’ ’;
}
1 1 1 1 1 1 …
1 2 3 4 5

21. 21
The do–while() Loop
do
<Loop body> ;
while (<Condition>); Con
ditio
n
Loop
Body
true
false

22. 22
The do – while() Loop
do
<Statement> ;
while (<Condition>) ;
do {
<Statement 1> ;
<Statement 2> ;
. . .
} while (<Condition>) ;

23. 23
i
Variable
#include <iostream>
using namespace std;
int main()
{
int i = 1;
do {
cout << ” * n”;
cout << ” *** n”;
cout << ”*****n”;
cout << ” * n”;
cout << ” * n”;
cout << endl;
i++;
} while(i <= 4);
}
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
*
***
*****
*
*
1
2
3
4
5
Screen

24. 24
i
Variable
#include <iostream>
using namespace std;
int main()
{
int i = 1;
do
{
i += 3;
cout << i << endl;
} while(i < 11);
}
4
7
10
13
1
4
7
10
13
Screen

25. 25
The for( ; ; ) Loop
for (<init> ; <condition> ; <change>)
<Loop body> ;
init is usually an assignment to give a loop counter an initial
value. Executed ONLY when entering the loop. Can also declare
variables.
condition is any statement returning an integral value and for
as long as it is true, the statement will be executed. Executed at
every pass.
change is a statement normally to modify the loop counter, so
that eventually it will make condition false and the loop will
terminate. Executed at every pass after the execution of the
loop body.

26. 26
Example 1
1 2 3 4 5 6
int main()
{
int i;
for(i=1; i<7; i++)
cout << i << ” ”;
}

27. 27
Example 2
1 2 3 4 5 6
int main()
{
int i;
for(i=1; i<7; ++i)
cout << i << ” ”;
}

28. 28
Example 3
9 8 7 6
int main()
{
int i;
for(i=9; i>5; --i)
cout << i << ” ”;
}