CHAPTER -4 Operators in Java

class - x

State whether the following statements are 'True' or 'False'

Question 1

The precedence of operators in Java follows BODMAS.

False

Question 2

The output of a++ will be 1, if int a = -1.

False

Question 3

The relational operators always result in terms of 'True' or 'False'.

True

Question 4

Given: int m=5; m*=5 then the value stored in m results in 55.
False

Question 5

The statement (a>b)&&(a>c) uses a logical operator.

True

Question 6

If int a=27,b=4,c=0; then c = a%b; results in 3.

True

Question 7

The statement p+=5 means p=p*5.

False

Question 8
In the precedence of logical operators; NOT is followed by AND.
True

Write the Java expressions for the following

Question 1

z = 5x3 + 2yx + y

Answer

z=5*x*x*x+2*y*x+y

Question 2

m = a2 + b2 / (a + b)

Answer

m = (a * a + b * b) / (a + b)

Question 3

s = ut + (1/2)at2

Answer

s = u * t + (1 / 2) * a * t * t

Question 4

f = uv / (u + v)

Answer

f = u * v / (u + v)

Question 5

d = √(3x + x2) / a + b

Answer

d = Math.sqrt(3 * x + x * x) / (a + b)

Question 6
p = a2 + b2 + 2ab

Answer

p=a*a+b*b+2*a*b

Question 7

y = 2(lb + bh + lh)

Answer

y = 2 * (l * b + b * h + l * h)

Question 8

p = a / b2 + b / a2

Answer

p = a / (b * b) + b / (a * a)

Question 9

z = x3 + y3 - y / z3

Answer

z = x * x * x + y * y * y - y / (z * z * z)

Question 10

q = 1 / √(a + b) + 3 / c2

Answer

q = (1 / Math.sqrt(a + b)) + 3 / (c * c)

Predict the output

Question 1

int c = (3<4)? 3*4:3+4;

Output
12

Explanation

As 3 is less than 4 so condition of ternary operator is true. Variable c is assigned the value of
expression 1 which is 3 * 4 = 12.

Question 2

int a = 14, b = 4;
boolean x = (a > b) ? true : false;

Output

true

Explanation

As 14 is greater than 4 so condition of ternary operator is true. Variable x is assigned the value of
expression 1 which is true.

Question 3

int x = 90;
char c = (x<=90)?'Z':'I';

Output

Explanation

As value of x is 90 so condition of ternary operator is true. Variable c is assigned the value of

expression 1 which is Z.

Question 4

int a = 18; int b = 12;

boolean t = (a > 20 && b < 15)? true : false;

Output

false

Explanation

The condition a > 20 is false as value of a is 18. So the logical AND operator — && returns
false. Variable t is assigned the value of expression 2 which is false.
Question 5

c = (val + 550 < 1700)? 200: 400;

if: (a) val = 1000 (b) val = 1500

Output

(a) 200
(b) 400

Explanation

When val = 1000, val + 550 = 1550. As 1550 is less than 1700 so condition of ternary operator is
true. Variable c is assigned the value of expression 1 which is 200.
When val = 1500, val + 550 = 2050. As 2050 is greater than 1700 so condition of ternary
operator is false. Variable c is assigned the value of expression 2 which is 400.

Answer the following questions

Question 1

What is an operator? What are the three main types of operators? Name them.

Answer

An operator is a symbol or sign used to specify an operation to be performed in Java

programming. The three main types of operators are Arithmetical, Logical and Relational.

Question 2

How is Java expression different from statement?

Answer

An expression is a set of variables, constants and operators i.e. an expression is a

combination of operators and operands. When an expression is assigned to a variable, the
complete set is referred to as a statement.

Question 3

Explain the following with one example each.

(a) Arithmetic operator

Answer
Arithmetic operators are used to perform mathematical operations on its operands.
Operands of arithmetic operators must be of numeric type. A few arithmetic operators
operate upon one operand. They are called Unary Arithmetic operators. Other arithmetic
operators operate upon two operands. They are called Binary Arithmetic operators. As an
example consider the below statement:
int a = 10 + 20;
Here, the addition arithmetic operator, represented by the symbol + will add 10 and 20. So
variable a will be 30.

(b) Relational operator

Answer

Relational operators are used to determine the relationship between the operands.
Relational operators compare their operands to check if the operands are equal to ( == ),
not equal to ( != ), less than ( < ), less than equal to ( <= ), greater than ( > ), greater than
equal to ( >= ) each other. The result of an operation involving relation operators is a
boolean value — true or false.
Example:
int a = 8;
int b = 10;
boolean c = a < b;
Here, as a is less than b so the result of a < b is true. Hence, boolean variable c becomes
true.

(c) Logical operator

Answer

Logical operators operate on boolean expressions to combine the results of these boolean
expression into a single boolean value.
Example:
int a = 7;
int b = 10;
boolean c = a < b && a % 2 == 0;
Here, the result of first boolean expression a < b is true and the result of second boolean
expression a % 2 is false. The logical AND operator ( && ) combines these true and false
boolean values and gives a resultant boolean value as false. So, boolean variable c
becomes false.

(d) Ternary operator

Answer

Ternary operator operates on three operands. Its syntax is:

condition ? expression 1 : expression 2
Ternary operator evaluates the condition. If the condition is true then result of ternary
operator is the value of expression 1. Otherwise the result is the value of expression 2.
Example:
boolean isLeapYear = true;
int febDays = isLeapYear ? 29 : 28;
Here, the ternary operator checks if the value of boolean variable isLeapYear is true or
false. As it is true, expression 1, which in this example is the value 29, is the result of the
ternary operator. So, int variable febDays becomes 29.

Question 4

Distinguish between:

(a) Unary & Binary arithmetic operator

Answer

Unary Arithmetic Operator Binary Arithmetic Operator

It operates on a single operand It operates on two operands
Increment (++) and Decrement (--) operators are Multiplication (*) and Division (/) are
examples of Unary Arithmetic Operators examples of Binary Arithmetic Operators

(b) Postfix increment and Prefix increment

Answer

Postfix Increment Prefix Increment

It works on the principle of CHANGE-
It works on the principle of USE-THEN-CHANGE.
THEN-USE.
The increment operator (++) is written after the The increment operator (++) is written
operand. before the operand.
Example:
int a = 99; Example:
int b = a++; int a = 99;
int b = ++a;
After the execution of these two statements, a will
After the execution of these two statements,
have the value of 100 and b will have the value of
both a and b will have the value of 100.
99.

(c) Postfix decrement and Prefix decrement

Answer

Postfix Decrement Prefix Decrement

It works on the principle of CHANGE-
It works on the principle of USE-THEN-CHANGE.
THEN-USE.
The decrement operator (--) is written after the The decrement operator (--) is written
operand. before the operand.
Example: Example:
 Postfix Decrement Prefix Decrement
int a = 100; int a = 100;
int b = a--; int b = --a;
After the execution of these two statements, a will After the execution of these two statements,
have the value of 99 and b will have the value of 100. both a and b will have the value of 99.

(d) (p != q) and !(p == q)

Answer

(p != q) !(p == q)
This expression uses the relational This expression first checks if values of p and q are equal
operator != (Not equal to) to using the relation operator == (equality). It then inverts the
determine if values of p and q are result of equality operator using the logical NOT (!) operator
different. to determine if values of p and q are different.

Question 5

What is the difference between

(a) / and % operator?

Answer

/ %
Division operator Modulus operator
Returns the quotient of division operation Returns the remainder of division operation
Example: int a = 5 / 2; Here a will get the value Example: int b = 5 % 2; Here b will get the value
of 2 which is the quotient of this division of 1 which is the remainder of this division
operation operation

(b) = and == ?

Answer

= ==
It is the assignment operator used for It is the equality operator used to check if a variable is
assigning a value to a variable. equal to another variable or literal.
Example:
Example: if (a == 10)
int a = 10;
This statement checks if variable a is equal to 10 or
This statement assigns 10 to variable a.
not.

Question 6(a)

What will be the output of the following code?

int k=5,j=9;
k+= k++ - ++j + k;
System.out.println("k="+k);
System.out.println("j="+j);

Output

k=6
j=10

Explanation

⇒ k = k + (k++ - ++j + k)
k+= k++ - ++j + k

⇒ k = 5 + (5 - 10 + 6)
⇒k=5+1
⇒k=6

Question 6(b)

If int y =10 then find int z = (++y*(y+++5));

Output

z = 176

Explanation

⇒ z = (11 * (11 + 5))

z = (++y*(y+++5))

⇒ z = (11 * 16)
⇒ z = 176

Question 6(c)

Give the output of the following expression:

a+= a++ + ++a + --a + a--; when a = 7;

Output

a = 39

Explanation

⇒ a = a + (a++ + ++a + --a + a--)

a+= a++ + ++a + --a + a--

⇒ a = 7 + (7 + 9 + 8 + 8)
⇒ a = 7 + 32
⇒ a = 39

Question 6(d)

What is the value of y after the execution?

y+= ++y + y-- + --y; when int y=8

Output

y = 33

Explanation

⇒ y = y + (++y + y-- + --y)

y+= ++y + y-- + --y

⇒ y = 8 + (9 + 9 + 7)
⇒ y = 8 + 25
⇒ y = 33

Question 7

Rewrite the following program segment using if-else statements instead of the ternary operator.

(a) String grade = (marks>=90)?"A": (marks>=80)? "B": "C";

Answer

String grade;
if (marks >= 90)
grade = "A";
else if (marks >= 80)
grade = "B";
else
grade = "C";

(b) commission = (sale > 5000) ? sale*10/100 : 0;

Answer

if (sale > 5000)

commission = sale * 10 / 100;
else
commission = 0;

(c) net = (salary > 10000) ? salary - (8.33/100)*salary : salary - (5/100)*salary

Answer
if (salary > 10000)
net = salary - (8.33/100) * salary;
else
net = salary - (5/100) * salary;

(d) s = (a + b < c || a + c <= b || b + c <= a) ? "Triangle is not possible": "Triangle is possible";

Answer

if (a + b < c || a + c <= b || b + c <= a)

s = "Triangle is not possible";
else
s = "Triangle is possible";

(e) c = (x >= 'A' && x<= 'Z') ? "Upper Case Letter" : "Lower Case Letter";

Answer

if (x >= 'A' && x <= 'Z')

c = "Upper Case Letter";
else
c = "Lower Case Letter";

Question 8

Rewrite the following using ternary operator.

(a)

if (x % 2 == 0)
System.out.println("Even");
else
System.out.println("Odd");

Answer

System.out.println(x % 2 == 0 ? "Even" : "Odd");

(b)

if (bill > 10000)

discount=bill*10.0/100;
else
discount=bill*5.0/100;

Answer

discount = bill > 10000 ? bill*10.0/100 : bill*5.0/100;

(c)
if(income < 10000)
tax = 0;
else
tax = 12;

Answer

tax = income < 10000 ? 0 : 12;

(d)

if(a > b)
{
if (a > c)
g = a;
else
g = c;
}
else if (b > c)
g = b;
else
g = c;

Answer

g = a > b ? a > c ? a : c : b > c ? b : c;

(e)

if (p >= 4750)
k = p * 5 / 100;
else
k = p * 10 / 100;

Answer

k = (p >= 4750) ? p * 5 / 100 : p * 10 / 100;