Learning Unit 7 Programming Theory

Question 1

Coding Programs with If Statements

Answer 1

• If and else are reserved words, IDE may indicate this by putting them in a different color.
• Pseudocode
  begin
  _____________________
  if ____________________
  then_________________
  else_________________
  end if
  _____________________
  end

Question 2

Relational Operators

Answer 2

• Double equals in Java is used to check equality.
• Single equals sign is used to assign/store a value in a variable.
• ! used for Not.

Question 3

Important points on the If statement

Answer 3

• If…else is 1 statement in Java
• Condition in an if statement can either be:
  True
  False

Question 4

Important that the layout of an if statement

Answer 4

Makes it easy to read.

Question 5

If there is one statement in a block

Answer 5

Curly brackets can be left off.

Question 6

Objects of string data type cannot be compared using ==:

Answer 6

String is not a primitive data type

Question 7

Else is optional:

Answer 7

No else, program continues with the next instruction after the end of if statement block.

Question 8

When to use a Nested if:

Answer 8

• Use an else if only one of the conditions can be true at the same time, so the program doesn’t check every if statement unnecessarily.
• Do not use an else: there is more that one condition to be tested and the conditions are independent of each other.

Question 9

Why are ‘a’ and ‘A’ not the same in Java?

Answer 9

• When Java compares the 2 letters, it compares their Unicode code values and not the actual characters.
• Since ‘a’ and ‘A’ don’t have the same Unicode values, the computer sees them as 2 totally different characters.

Question 10

How are conditions evaluated in Java

Answer 10

Arithmetic and logical expressions are evaluated as sums by the Arithmetic Logic Unit (ALU) in the processor.

Question 11

The NOT(!) operator

Answer 11

&& makes your program more efficient.

Question 12

|| Conditional OR:

Answer 12

Java will always carry out logical operators in the following order:
- Brackets
- NOT
- AND
- OR

Question 13

A problem when using If Statement - A Valueless Variable

Answer 13

• When a variable is only given a value in the if statement blocks: if none of the if statement are true Java knows that the variable will not get a value.
• Any variable that is only assigned a value in if statements must be initialized before the if statement so that it definitely gets a value in the program.
• No.s are usually assigned to 0
• Strings are initialized to an empty string.
• Characters cannot be initialized to nothing: must be character.