FP 201 Unit 2 - Part 3

FP 201 – Programming
Fundamentals
Operators & Expressions

Learning outcome
By the end of the course, students should be able to:
Define the following operators:
a. Arithmetic operator
b. Assignment operator
c. Increment and decrement operator
d. Relational operator
e. Logical operator
Explain operators’ precedence
Explain type conversion
Write expression using operator
Use expression in program

Operators
Operator Action
- subtraction (also unary minus)
+ addition
* multiplication
/ division
% modulus division
-- decrement
++ increment
&& AND
|| OR
! NOT

Operators
Is a symbol that instructs compiler to perform an operation
or action.

Arithmetic Operators
Perform four fundamental operations which are addition,
subtraction, multiplication and division.
Operator Description Example Result
* Multiplication 2*8 16
/ Division 8/2 4
+ Addition 2+8 10
- Subtraction 8-2 6
() Parentheses. For grouping (8+2) 10
% Modulus. Divides two number and 4%3 1
returns just the remainder portion

Arithmetic Operators
arithmetic expressions are evaluated with some rule called
operator precedence.
multiplications (*) and divisions (/) are evaluated first
additions (+) and subtractions (-) are performed last.

Activity 1

Write the resultant value of the following expressions.

Expression Result
14-4
14+4
14* 4
14/4
14%4

ACTIVITY 2
Calculate the total marks for the given five subjects.
Declare appropriate variables, assign values as given
below:
English = 85
Maths = 100
History = 75
Geography = 70
Art = 85

 calculate the total marks
 calculate the average

#include<iostream>

using namespace std;
int main()
{
int english = 85, maths = 100, history = 75, geography = 70, art = 85;
int sum=0;

sum=english+maths+history+geography+art;
cout<<"Sum is: "<<sum<<endl;;

return 0;
}

#include<iostream>

int main()
{
int english = 85, maths = 100, history = 75, geography = 70, art = 85;
int sum=0, average=0;

sum=english+maths+history+geography+art;
average=sum/5;

cout<<"Sum is: "<<sum<<endl;
cout<<"Average is:"<<average<<endl;

return 0;
}

Assignment Operator
variables are given a value through the use of assignment
operator (=)
general form:
variable = expression;
eg:
int x, y;
x = 2;
y = 5*x; // y = 10
x = x + 4; // x = 6
y = y/2; // y = 5

Assignment Operator
The value of an assignment can be used in another
assignment.

This is a chained assignment.
Eg:
m = (n = 66) + 9; // n = 66 and m = 75
x = y = 22; // x = 22 and y = 22

Compound Assignment Operators
(+=), (-=), (*=), (/=), (%=)

allow us to use assignment and an arithmetic operator
together.

general form is:
variable operator= expression;

Compound Assignment Operators
Operator Description Example Equivalent to

+= add and assign x += 3 x=x+3

-= subtract and assign x -= 5 x=x-5

*= multiply and assign x *= 4 x=x*4

/= divide and assign x /= 2 x=x/2

%= find reminder and assign x %= 9 x=x%9

In Class Exercise
 Given the following declaration and initial assignment:

int i = 4, j = 21, k;
float x = 94.55, y;
char a = ‘z’, b = ‘t’, c =‘ ‘;

Determine the value for the following assignments:
 k=i*j
y = x + i
y = k = j
 a = b =c
 i += i

Increment & Decrement Operator
increment operator (++) and decrement operator (--)
increase or reduce by one the value stored in a variable.
the following are equivalent in functionality.
x++;
x += 1;
x = x + 1;
characteristic of this operator:
can be used both as a prefix and as a postfix.
eg: a++ or ++a
the results is different

Prefix
When a prefix expression (++x or --x) is used as part
of an expression, the value returned is the value
calculated after the prefix operator is applied

int x = 0;
int y = 0;
y = ++x;
// result: y=1, x=1 x is incremented by 1 and the result is
assigned to y

Postfix
When a postfix expression (x++ or x--) is used as part
of an expression, the value returned is the value
calculated before the postfix operator is applied

int x = 0;
int y = 0;
y = x++;
// result: y=0, x=1 original value of x is stored, x is
incremented, original value of x is assigned to y

Increment & Decrement Operator
eg:
a = 5; // a = 5
b = a++; // b = a = 5, then a = 5+1 = 6
c = ++a; // a = 6+1 = 7, then c = a = 7

Relational Operator
 Control statements use relation operators in order to compare two objects,
which results in a value that is either true (1) or false (0).
 There are six relational operators as follows:

Operator Description Example Value
< less than x<y 6<9 1

<= less than or equal to x <= y 12 <= 13 1

> greater than x>y 7 > 10 0

>= greater than or equal to x >= y 9 >= 5 1

== equal to x == y 7 ==5 0

!= not equal to x != y 6 != 5 1

Logical Operator
Operator Description Example

logical AND, conjunction.
&& Both sides must be true for the result to x > 2 && y == 3
be true

logical OR, disjunction.
|| The result is true if either side or both x > 2 || x <= 9
sides are true.

! logical NOT, negation !(x>0)

Condition1 Condition2 && ||

true true true true

true false false true

false true false true

false false false false

Logical Operator
using these operators, we can form a Boolean Expression that
can be either true or false.
Boolean expressions evaluate to integer values.
The value 0 means 'false' and all non-zero value means 'true'.
There are also two literal constants used with bool
variables: true and false.

In Class Exercise
What is the difference between x = 3 and x == 3?
Given a = 2, b = 5, c = 7 determine the value for the
following expressions either TRUE or FALSE: :
1. a < 2 && b > 5
2. c >= a
3. a < b || b > c
4. c != 10
5. a == 25

Operator Precedence
Determines the order in which mathematical computations
and operations are performed in an expression.

Operator Precedence

Given a=b = 5, c = 2; solve the following expression
a+b*2/c–5
=5+5*2/2–5
= 5 + 10 / 2 – 5
=5+5–5
= 10 – 5
=5

In Class Exercise
Given x = 10, y = 7, z = 2; solve the following expression
x + 2y – z
x / z – x * x + y
x * y % z
5 ( x + y + z ) – x / z
++x*y – y*z

Type conversion/Type Casting
Is the conversion of a value of one data type into another
data type.
Typecasting consist of two types:
 Implicit conversion
 Explicit conversion

Implicit conversion
A value of data type with lower range is assigned to a variable
of data type with higher range
Lower range to higher range

Example
#include<iostream>
OUTPUT
void main() Result: 4.2555
{
double x; // Size is 8 bytes
int y=2; //Size is 4 bytes
float z=2.2555f;
x=y+z; //Implicit conversion
cout<<"Result: "<<x;
}

Explicit conversion
A value of data type with higher range is assigned to a
variable of data type with lower range
Higher range to lower range

Explicit conversion leads to data loss.

Example
#include<iostream>

OUTPUT
void main() The total value is:300
{
int total_value;
double book1 = 300.46;
total_value=(int)book1; // Explicit conversion
cout<<"The total value is:"<<total_value;
}

Exercise
Write a program to declare a variable d of type double.
Assign the value 102.5789 to d. Declare a float variable fl.
Assign the value of d to fl by performing an explicit
conversion and print the value on the screen.

Answer
#include<iostream>
void main() OUTPUT
{ Value of the float variable fl = 102.579
double d=102.5789;
float fl;
fl=(float)d; // Explicit conversion
cout<<"Value of the float variable fl = "<<fl;
}

Summary
In this presentation, you learnt the following:
Operator is a symbol that instructs compiler to perform an
operation or action.
Typecasting is the conversion of data type of the value of a
variable into another.
There are two types of casting: implicit conversion and
explicit conversion.

FP 201 – Programming
Fundamentals with C++
Input Output Statements

Learning outcome
By the end of the course, students should be able to:

Identify the syntax use for input and output
Write program that use the input and output statements

Input/Output Statements
The standard C++ library includes the header file
iostream, where the standard input and output stream
objects are declared.

cout to output data to the screen and

cin to input data from the keyboard.

Standard Output
standard output:
need to use cout, followed by the insertion operator (<<)
eg:
cout << "Hello World!"; // Outputs "Hello World!"
on the screen
cout << 1299; // Outputs the number 1299 on the
screen
cout << x; // Outputs the content of x on the
screen
insertion operator (<<) may be used more than once in a
single statement:
cout << "Hi, " << "this is " << "a simple C++ statement";

Standard Output
Note that, cout does not add a line break.
For example:
cout << "Computer Programming ";
cout << "is important for engineers.";
will be output as:
Computer Programming is important for
engineers.

Standard Output
A line break can be added by inserting a 'n' character or a
using a endl manipulator.

cout << "Computer Programming n";

cout << "Computer Programming " << endl;

These two produce the following (same) output: Computer
Programming
is important for engineers.

Standard Input
 Handling the standard input is done by applying the
overloaded operator of extraction (>>) on the cin stream
 Value can be input from the keyboard and assigned to a
variable x as follows:
cin >> x;
 and two variables can assigned as any of the follows:
cin >> x;
cin >> y;
cin >> x >> y;

Code Example
// Calculates the sum of two integers
#include <iostream>

int main()
{
int a, b, total;
cout << "Enter two integers to be added: ";
cin >> a >> b;
total = a + b;
cout << "The sum is " << total << endl;
return 0;
}

Code Example
// Calculates the area of a triangle
// given an input of the triangle base and height.
#include <iostream>

int main()
{
float base, height, area;
std::cout << "Enter the base and height of the
triangle: ";
std::cin >> base >> height;
area = 0.5*base*height;
std::cout << "The area of the triangle is "
<< area << std::endl;
}

Q&A
Develop a program that can calculate the total and average of
four numbers that is input by user.

#include <iostream>

int main()
{
int a, b, c, d, total, average;
cout << "Enter four integers to be added: ";
cin >> a >> b>>c>>d;
total = a + b + c + d;
average = total/4;
cout << "The sum is " << total << endl;
cout<< "The average is "<< average << endl;

return 0;
}

Summary
In this presentation, you learnt the following:

cout to output data to the screen
cin to input data from the keyboard.
cout use insertion operator (<<)
cin use overloaded operator of extraction (>>)

FP 201 Unit 2 - Part 3

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