Chapter 5 PDF

Question 1

Describe sequence in the flow of control

Answer 1

Execute instructions in order

Question 2

Describe method calls in the flow of control

Answer 2

Transfer control to method, execute instructions in method, then return with or without a value

Question 3

Describe selection in the flow of control

Answer 3

Execute different instructions depending on the data

Question 4

Describe looping in the flow of control

Answer 4

Repeat a set of instructions for different data

Question 5

Describe equality operators

Answer 5

They’re used to determine if the values of two expressions are equal or not equal

Question 6

What is special about equality operators

Answer 6

Must be used with a primitive data type and object references, not to compare object data

Question 7

What is a common error made with equality operators

Answer 7

Equality operators (==) and easily confused with the assignment operator (=)

Question 8

What is relational operators used for

Answer 8

Relational Operators are used to compare the values of two expressions

Question 9

What is the result for relational operators

Answer 9

The result for relational operators is either true or false

Question 10

What is ! used for in programming

Answer 10

! is the NOT operator

Question 11

What is the ! (NOT OPERATOR) used for

Answer 11

The NOT operator is used to evaluate to the inverse of the value of its operand. (EX: If the operand is true the result will be the opposite)

Question 12

What is && used for in programming

Answer 12

&& is the AND operator

Question 13

What is the && (AND OPERATOR) used for

Answer 13

The AND operator takes two boolean expressions as operands, if both operands are true then the result is true. Otherwise the result is false.

Question 14

What is || used for in programming

Answer 14

|| is the OR operator

Question 15

What is the OR operator used for

Answer 15

The OR operator takes two boolean expressions as operands. If both operands are false, the result will be false and otherwise it’ll be true.

Question 16

In any logical operator, how are the operands evaluated?

Answer 16

Operands are evaluated left to right for any logical operator

Question 17

What occurs if the result of the logical operator can be determined after evaluating the first operand

Answer 17

Only the first operand will be evaluated and the second one will be ignored

Question 18

What is the result if the first operand of an OR statement is true

Answer 18

The result of the statement will be TRUE

Question 19

What is the result if the first operand of an AND statement is false

Answer 19

The result of the statement will be FALSE

Question 20

What is a common error when testing three ints

Answer 20

Each operand of a logical operator must be a boolean expression or else you will have a compiler error

Question 21

What are DeMorgans Laws

Answer 21

1. NOT( A AND B ) = ( NOT A ) OR ( NOT B )

2. NOT( A OR B ) = ( NOT A ) AND ( NOT B )

Question 22

How would you find an equivalent expression using DeMorgans Laws

Answer 22

1. Change AND to OR
2. Change OR to AND
3. NEGATE EACH OPERAND EXPRESSION

Question 23

What is an if statement used for

Answer 23

If statements are used when the program should perform an operation for one set or data but do nothing for all other data

Question 24

What is special about curly brackets if the true block of an if statement only contains one statement

Answer 24

Curly braces are optional if the true block contains only one statement

Question 25

Describe a simple IF Flow of Control

Answer 25

If the condition evaluates to true, the true block is executed.
If the condition evaluates to false, the true block is skipped

Question 26

What is a a common error with if statements

Answer 26

Do not put a semicolon after the condition in an if statement. Doing so would indicate that the true block is empty and will cause a logic error

Question 27

When is the if/else statement used

Answer 27

Used when Data falls into two mutually exclusive categories and the program should perform different operations for each set of data

Question 28

What is special about curly brackets if the true block of an if/else statement only contains one statement

Answer 28

Curly braces are optional if the true block contains only one statement

Question 29

Describe an id/else flow of control

Answer 29

If the condition is true, then the true block is executed.

If the condition is false then the false block is executed

Question 30

What is scope

Answer 30

The region within a program where an identifier can be referenced.

Question 31

Where does the scope of a variable end and begin

Answer 31

The scope of a variable extends from the point of declaration to the end of the block in which it is declared

Question 32

What are some examples of blocks

Answer 32

Classes
Methods
If statements true and false blocks

Question 33

When is an if/else if statement used

Answer 33

Used when data falls into multiple, mutually exclusive categories and the program should perform different operations for each set of data

Question 34

Describe the if/else if Flow of Control

Answer 34

• If the first condition is true, the first true block is executed. The rest of the if/else statement is skipped.
• If the n^th condition is true then the n^th true block is executed. The rest of the if/else statement is skipped.
• If no condition is true, the false block is executed.

Question 35

What are nested if statements

Answer 35

If statements can be written as part of the true or false block of another if statement.

Question 36

What is needed if you nest an if statement

Answer 36

If you nest an IF statement more information is required beyond the results of the first if condition

Question 37

What occurs if you don’t assign an else clause in a nested if statement

Answer 37

The compiler will match any else clause with the most previous if statements that doesn’t already have an else clause

Question 38

What can curly brackets be used for in a nested if/else statements

Answer 38

You can use curly brackets to force a desired if/else pairing

Question 39

What is a “Dangling Else”

Answer 39

A dangling else occurs when an else clause cannot be paid with an if condition

Question 40

What can occur with floating point representation

Answer 40

Minor rounding errors can occur in calculations, causing the equality operator not to consider the values equal.

Question 41

How do we solve the equality operator not being able to consider values equal (in relation to rounding errors)

Answer 41

Consider a small threshold value. If the absolute value of the difference between the two values is less than the threshold value, then the two floating point numbers will be considered equal.

Question 42

What does the equality operator compare

Answer 42

The equality operator compares object references. ie: compares that they point to the same object… doesn’t compare the data

Question 43

How would you compare object data instead of comparing the objects themselves

Answer 43

You would use the equals method

Question 44

What is the common error when using equality operators

Answer 44

You do not use equality operators to compare object data, instead use the equals method

Question 45

What are strings considered

Answer 45

Strings are objects (data)

Question 46

How would you compare two strings

Answer 46

Use the equals method since Strings are objects (data)

Question 47

What does a conditional operator do

Answer 47

A conditional operator contributes one of two values to an expression based on the value of the condition

Question 48

What are some uses of conditional operators

Answer 48

Handling invalid input

Outputting similar messages

Question 49

When is a switch statement used

Answer 49

In some selection operators, the switch statement can be used instead of an if/else/if statement

Question 50

What are the requirements for using a switch statement

Answer 50

Can be used when we are comparing the value of an expression to constant intergers (byte, short, int), characters (char) or Strings.

Question 51

How is the switch operation performed

Answer 51

The expression is evaluated, then its value is compared to the case constants in order. When a match is found, the statements following that case constant are executed in sequence until either a break statement or the end of a switch block is reached.

Question 52

What are some optional aspects when using a switch statement

Answer 52

The break statement is optional
The default label and its statements are also optional
The statements under the case constant are also optional

Question 53

Why is the break statement optional when using a switch statement

Answer 53

The break statement is optional when using a switch statement because the job of the break is to terminate execution of the switch statement

Question 54

Why is the default label and its statements optional when using the switch statement

Answer 54

The default label is optional because they are executed only when the value of the expression does not match any of the case constants

Question 55

Why are the statements under the case constant optional when using a switch statement

Answer 55

The statements under the case constant are also optional so multiple case constants can be written in sequence if identical operations will be performed for those values

Question 56

What are common errors with break statements

Answer 56

(Remember that once a match is found, all succeeding statements are executed until a break statement is encountered).
Be careful to code a break statement when you have finished the processing of a value, otherwise you may execute unintended statements