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Solutions for Computer Applications, Class 9, ICSE
What are logical operators? Give an example of each.
Logical operators operate only on boolean operands and are used to construct complex decision-making expressions. Some of the logical operators are given below:
| Operator | Symbol |
|---|---|
| Logical AND | && |
| Logical OR | || |
| Logical NOT | ! |
What is an assignment operator? Give an example.
Assignment operator is used to assign the value of an expression to a variable. It has the following syntax:
variable = expression;For example,
totalMarks = 780;The above statement assigns the value of 780 to the variable totalMarks. Any previous value stored in totalMarks variable is overwritten by this new value.
Explain the shorthand assignment operator with an example.
Java provides shorthand assignment operators for all the arithmetic binary operators. Shorthand assignment operators follow the below syntax:
variable = variable operation expression;Taking the example of shorthand addition operator, the expression x = x + 3 can be rewritten as x += 3;
What is the use and syntax of a ternary operator?
Ternary operator is used to check if a condition is true and false. Depending on whether the condition tests true or false, expression 1 or expression 2 is evaluated. Its syntax is:
boolean-expression ? expression1 : expression2;State the difference between = and ==.
| = | == |
|---|---|
| It is the assignment operator used for assigning a value to a variable. | It is the equality operator used to check if a variable is equal to another variable or literal. |
| E.g. int a = 10; assigns 10 to variable a. | E.g. if (a == 10) checks if variable a is equal to 10 or not. |
If a = 5, b = 9, calculate the value of:
a += a++ - ++b + a
a += a++ - ++b + a
⇒ a = a + (a++ - ++b + a)
⇒ a = 5 + (5 - 10 + 6)
⇒ a = 5 + 1
⇒ a = 6
a++ first uses the current value of a (which is 5) in the expression and then increments it to 6. ++b first increment the current value of b to 10 and uses this incremented value in the expression.
If x = 3, y = 7, calculate the value of:
x -= x++ - ++y
x -= x++ - ++y
⇒ x = x - (x++ - ++y)
⇒ x = 3 - (3 - 8)
⇒ x = 3 - (-5)
⇒ x = 3 + 5
⇒ x = 8
What will be the output of the following if x=5?
i. 5 * ++x
ii. 5 * x++
i. 5 * ++x
⇒ 5 * 6
⇒ 30
ii. 5 * x++
⇒ 5 * 5
⇒ 25
What is type conversion? How is an implicit type conversion different from explicit type conversion?
Type conversion is a process that converts a value of one data type to another data type.
In an implicit conversion, the result of a mixed mode expression is obtained in the higher most data type of the variables without any intervention by the user. For example:
int a = 10;
float b = 25.5f, c;
c = a + b;In case of explicit type conversion, the data gets converted to a type as specified by the programmer. For example:
int a = 10;
double b = 25.5;
float c = (float)(a + b);What do you understand by type conversion?
Type conversion is a process that converts a value of one data type to another data type.
What is typecasting in Java? Give an example.
The process of converting a value of one data type to another data type is called typecasting. For example:
int a = 10;
double b = 25.5;
float c = (float)(a + b);What are precedence and associativity?
Precedence of operators refers to the order in which the operators are applied to the operands in an expression.
Associativity of operators refers to the direction of execution of operators ("Left to Right" or "Right to Left") when operators in an expression have the same precedence.
Evaluate the following expressions, if the values of the variables are a = 2, b = 3 and c = 3
i. a - (b++) * (--c)
ii. a * (++b) %c
i. a - (b++) * (--c)
⇒ 2 - 3 * 2
⇒ 2 - 6
⇒ -4
ii. a * (++b) %c
⇒ 2 * 4 % 3
⇒ 8 % 3
⇒ 2
Write the Java expressions for the following:
i. (a + b)2 + b
Math.pow(a+b, 2) + b
ii. a2 + b2
a * a + b * b
iii. z = x3 + y3 + (xy) / 3
z = Math.pow(x, 3) + Math.pow(y, 3) + x * y / 3
iv. f = a2 + b2 / a2 - b2
f = (a * a + b * b) / (a * a - b * b)
v. z = ab + bc + ca / 3abc
z = (a * b + b * c + c * a) / (3 * a * b * c)
vi. 0 <= x <= 50
x >= 0 && x <= 50
Rewrite the following statements without using shorthand operators.
a. p /= q
b. p -= 1
c. p *= q + r
d. p -= q - r
a. p = p / q
b. p = p - 1
c. p = p * (q + r)
d. p = p - (q - r)
Determine the output of the following program.
public class Test
{
public static void main(String[] args)
{
int a = 1, b = 2;
System.out.println("Output1: " + a + b);
System.out.println("Output2: " + (a + b));
}
}What is the difference between the following two statements? Explain the results.
x -= 5;
x =- 5;
The first statement, x -= 5; subtracts 5 from x and assigns the result back to x. It is equivalent to x = x - 5;
The second statement, x =- 5; assigns the value of -5 to x.
What is concatenation? On which data type is concatenation performed?
Concatenation means joining two strings together. It is performed on String data type.
Determine the output of the following program.
public class PredictOutput1
{
public static void main(String args[])
{
int a = 4, b = 2, c = 3;
System.out.println("Output 1: " + (a = b * c));
System.out.println("Output 2: " + (a = (b * c)));
}
}Determine the output of the following program.
public class PredictOutput2
{
public static void main(String args[])
{
int a = 6, b = 2, c = 3;
System.out.println("Output 1: " + (a == b * c));
System.out.println("Output 2: " + (a == (b * c)));
}
}Determine the output of the following program.
public class PredictOutput3
{
public static void main(String args[])
{
int a = 2, b = 2, c = 2;
System.out.println("Output 1: " + (a + 2 < b * c));
System.out.println("Output 2: " + (a + 2 < (b * c)));
}
}An operator taking only single operand for its operation is called ...........
Which one of the following is not a binary operator?
Which one of the following is not a valid operator in Java?
The statement i = i + 1 is equivalent to ...........
For x = 5, the statement sum = ++x + 8 evaluates to ...........
The statement (1>0) && (1<0) evaluates to ...........
The statement (1>0) || (1<0) evaluates to ...........
The statement (1==1)? 1: 0 evaluates to ...........
The expression 13 % 3 gives the output ...........
The expression 13 / 3 gives the output ...........
The statement System.out.println("six " + 3 + 3); gives the output ...........
The expression 4 + 8 % 2 gives the output ...........
Arithmetic operators + and - also have a unary form.
True
Operators = and == perform the same operation in Java.
False
The expression 10 % 4 evaluates to 2.
True
The expression 3 / 4 evaluates to 0.
True
The expressions 3 + 4 and "3" + "4" evaluate to the same value.
False
The expression x = x + 7 is same as x =+ 7.
False
The new operator allocates memory during runtime.
True
The statements x = 7 and x == 7 are same.
False
The expression z =- 7 is same as z = z-7.
False
The assignment operator (=) is a binary operator.
True