Operators - ICSE Very Important

Operators

There are several operators available in Java and some of the important operators in Java are as follows:

Arithmetic Operators:

These operators are used for performing mathematical calculations such as Addition, subtraction, multiplication, division and remainder.

Arithmetic Operators	Operation
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus

Increment/Decrement Operators

Increment operator is represented as ++ and Decrement operator is represented as --. These operators work in two forms: 

Prefix form: When used in Prefix form, it follows the rule Change-then-use. For example, ++x

Postfix form: When used in Postfix form, it follows the rule Use-then-Change. For example, x++

Example:

int S = 5,a = 10; S = S + ++a;   Value of S will be 16.

int S = 5,a = 10; S = S + a++;   Value of S will be 15.

Relational Operators

These operators are also called comparison operators. They compare the values of two variables. They are:

Relational Operators	Description
>	Greater than
<	Less than
==	Equal to
>=	Greater than or equal to
<=	Less than or equal to
!=	Not Equal to

Logical Operators

These operators are used to combine relational operators to make complex expressions for decision making.

Logical Operators	Description
&&	AND
||	OR
!	NOT

Conditional Operator: Java offers a shortcut conditional operator (?:) that stores a value depending on a condition. This condition is also known as Ternary Operator, i.e., it requires three operands:

expression1? expression2: expression3

int marks = 56;

String result = marks>35? “Pass”:”Fail”;

Here, Answer will be Pass because test expression marks>35. Here, value stored within marks namely variable is 56 and it is clear that 56>35 and that is the reason due to which, the identifier result will have value “Pass” or else, result will have value “Fail”.

Practice 1:

Evaluate expression when value of X = 5

X+=X++ + ++X + --X +X

Solution:

X = 5+(5+7+6+6)

X = 5+(24)

X = 5+24

X = 29

Practice 2:

Evaluate expression when value of a = 7

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

Solution:

a = 7+(7+9+8+8)

a = 7+(32)

a = 7+32

a = 39

Practice 3:

Evaluate the value of n if value of p = 5, q = 19

int n = (q-p)>(p-q)?(q-p):(p-q)

Solution:

int n = (q-p)>(p-q)?(q-p):(p-q)

int n = (19-5)>(5-19)?(19-5):(5-19)

int n = 14>-14?14:-14

int n = 14

Practice 4:

Assume value of basic = 1500, what will be the value of tax after the following statement is executed?

tax = basic>1200? 200:100;

Solution: 200

Answer is 200 as test expression  is basic>1200. Here, value of basic is 1500 and it is clear that 1500>1200 due to which, the identifier tax will have value 200.

Practice 5:

Give the output of the following:

int x = 2, y = 4, z = 1;

int result = (++z)+y+(++x)+(z++);

Solution:

int result = (2)+4+(3)+(2)

int result = 2+4+3+2

int result = 6+5

int result = 11

Practice 6:

What is the value of x1 if x = 5?

x1 = ++x - x++ + --x

x1 = 6-6+6

x1 = 0+6

x1 = 6

Practice 7:

Evaluate the following if the value of x = 7, y = 5

x+ = x++ +x+ ++y

x = x+(x++ +x+ ++y)

x = 7 + (7+8+6)

x = 7+21

x = 28

Practice 8:

Give the output of the following:

int i = 10, m = 9;

String e = (m%i ==9)?"YES":"NO ";

System.out.println(e);

Answer is YES as test expression  is 9%10==9. Here, values of i and m are 10 and 9 respectively and it is clear that remainder value is coming to 9 due to which, the identifier e will have value YES.

Practice 9:

Rewrite the following using ternary operator:

if(bill>10000)

  discount = bill * 10.0/100;

else

   discount = bill * 5.0/100;

Solution:

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

Practice 10:

Rewrite the following using ternary operator:

if(n1>n2)
   r = true;
else
   r = false;

Solution:
r = (n1>n2)?true;false;

Practice 11:

What is the value of y after evaluating the expression given below?

y+ = ++y +y-- + --y, when int y = 8

Solution:

y = y+(++y + y-- +--y)

y = 8+(9+9+7)

y = 8 + (25)

y = 8+25

y = 33

Practice 12:

If int y = 10, then find

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

Solution:

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

           (11*(11+5))

           (11*16)

           176

Practice 13:

char ch = 'F';

int m = ch;

m = m+5;

System.out.println(m+ "" +ch);

Solution:

char ch = 'F' [ASCII code of F is 70]

int m = 70;

m = 70+5;

m = 75

Output will be:

75 F

Practice 14:

What is the output of the following program snippet?

char x = 'A';

int m;

m = (x=='a')?'A':'a';

System.out.println("m= "+m);

Solution:

m = 97

Practice 15:

What is the output of the following method?

public static void main(String[]args)

{

    int a = 5;

    a++;;

    System.out.println(a);

    a-=(a--)-(--a);

    System.out.println(a);

}

Solution:

First statement will produce 6

Second statement calculation is as follows:

a = a-(a--)-(--a)

a = 6-(6)-(4)

a = 6-6-4

a = 6-2

a = 4

Final output shall be

6

4

Practice 16:

Write a java expression for:

Solution:

u*t+0.5*f*Math.pow(t,2)

Practice 17:

Evaluate the expression:

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

where x = 20, y = 10

Solution:

z = 21*(10)-9

z = 21*10-9

z = 210-9

z = 201

Practice 18:

What will be the value of x after executing the following statement?

x=(x<y)?(y+x):(y-x);

If int x = 15, y = 20;

Solution:

x = (15<20)?35:5

As condition is correct, hence 2nd expression will be executed i.e. 35

Practice 19:

Write java expression for the following:

|x²+2xy|

Solution:

Math.abs(x*x+2*x*y)

Practice 20:

Give the output of the following code:

String A = "26", B = "100";

String D = A+B+"200";

int x = Integer.parseInt(A);

int y = Integer.parseInt(B);

int d = x+y;

System.out.println("Result 1 = "+D);

System.out.println("Result 2 = "+d);

Solution:

Result 1 = 26100200

Result 2 = 126

Practice 21:

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

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

Solution:

if(mark>=90)

{

    grade = "A";

}

else if(mark>=80)

{

    grade = "B";

}

else

{

    grade = "C";

}

Practice 22:

Evaluate the following expression. Given a=2,b=3,c=9.

a) a-(b++)*(--c)

Solution:

=2-(3)*(8)

=2-3*8

=2-24

=-22

b) a*(++b)%c

=2*(4)%9

=2*4%9

=8%9

=8

Practice 23:

Give value of x for the given expression:

a) int x = 50;

    x%=4

Solution:

x = x%4

x = 50%4

x = 2

b) int a = 10;b=20;

    boolean x;

    x=a>5 && b>5;

Solution:

x = 10>5 && 20>5;

As it is seen that both the expressions are correct and hence, answer will come to true.

c) int a =5, b = 10;

    boolean x;

    x = a>10!!(b+5>=15 && b-5<7)

Solution:

The output will be true.