TTS Swift Notes: Basic Operators

Question 1

What is an operator?

Answer 1

A special symbol or phrase that one uses to check, change, or combine values. EX: +, &&, ++i, etc

Question 2

What are the arithmetic operators?

Answer 2

+, -, *, /, % (modulo)

• 1 + 2 // equals 3
• 5 - 3 // equals 2
• 2 * 3 // equals 6
  10. 0 / 2.5 // equals 4.0

Question 3

What are the two range operators?

Answer 3

a..<b></b>

Question 4

What are the three kinds of operators?

Answer 4

Unary, binary, and ternary.

Question 5

What do unary operators operate on?

Answer 5

A single target (EX: -a, !b, i++)

Question 6

What do binary operators operate on?

Answer 6

Two targets (EX: 2 + 3)

Question 7

What does the ternary operator operate on?

Answer 7

Three targets. (EX: a ? b : c)

Question 8

What is an operand?

Answer 8

A value that an operator affects.

Question 9

What does an assignment operator do?

Answer 9

The assignment operators (a = b) initializes or updates the value of a with the value of b.

• let b = 10
• var a = 5
• a = b
• // a is now equal to 10

Question 10

• What is the symbol for the increment operator?

Answer 10

++

Question 11

What is the symbol for the decrement operator?

Answer 11

–

Question 12

The increment and decrement operators change the value by how many?

Answer 12

One

Question 13

• ++i is shorthand for what?

Answer 13

i = i + 1

Question 14

–i is shorthand for what?

Answer 14

i = i - 1

Question 15

If the operator is written before the variable, it increments the variable _______ returning its value.

Answer 15

Before

Question 16

If the operator is written after the variable, it increments the variable_______ returning its value.

Answer 16

After

Question 17

What is a unary minus operator?

Answer 17

The (-) prepended directly before the value it operators on, without any white space.

Question 18

What are examples of compound assignment operators?

Answer 18

+=, -=, =

Question 19

The expression “a += 2” is shorthand for what?

Answer 19

a = a + 2

The addition and assignment are combined into one operator that performs both tasks at the same time.

Question 20

Does the compound assignment operator return a value?

Answer 20

No.

Question 21

What are the six comparison operators?

Answer 21

Equal to (a == b)
     Not equal to (a != b)
     Greater than (a > b)
     Less than (a = b)
     Less than or equal to (a

Question 22

What are the two identity operators?

Answer 22

===

!==

Question 23

What do you use identity operators to test?

Answer 23

Whether two object references both refer to the same object instance.

Question 24

What do comparison operators return?

Answer 24

A Bool value.

Question 25

What are the three parts of the ternary conditional operator?

Answer 25

question ? answer1 : answer 2

Question 26

In the case of (a ?? b), what does a nil coalescing operator do?

Answer 26

It unwraps an optional a if it contains a value, or returns a default value b if a is nil.

Question 27

The nil coalescing operator (a ?? b) is shorthand for what?

Answer 27

a != nil ? a! : b

Question 28

In the case of a nil coalescing operator, if the value of a is non-nil, the value of b is not what?

Answer 28

Evaluated.

Question 29

What does a closed range operator look like?

Answer 29

(a…b)

Question 30

What does a half-open range operator look like?

Answer 30

(a..<b></b>

Question 31

A closed range operator includes what values?

Answer 31

A through B (i.e., all values)

Question 32

A half-open range operator does not include what value?

Answer 32

B (ie, all values but the last one)

Question 33

What are the three logical operators?

Answer 33

Logical NOT (!a)
      Logical AND (a && b)
      Logical OR (a || b)

Question 34

What do logical operators do?

Answer 34

They modify or combine the Boolean logic values true and false.

Question 35

What does the logical NOT operator do?

Answer 35

It inverts a Boolean value so that true becomes false and vice versa.

Question 36

What does the logical AND operator do?

Answer 36

It creates logical expressions where both values must be true for the overall expression to also be true.

Question 37

What does the logical OR operator do?

Answer 37

It creates logical expressions in which only one of the two values has to be true for the overall expression to be true.

Question 38

Can you combine logical operators?

Answer 38

Yes.

• if enteredDoorCode && passedRetinaScan || hasDoorKey || knowsOverridePassword {
• print(“Welcome!”)
• } else {
• print(“ACCESS DENIED”)
• }

// prints “Welcome!”