learngo/10-constants/questions/questions.md

What's a magic value?

1. A value which pops up from somewhere
2. Merlin the Wizard's spell
3. An unnamed constant value in the source code CORRECT
4. A named constant

What's a named constant?

1. A constant with a cool name
2. A constant value declared with a name CORRECT
3. A literal value converted to a name

How to declare a constant?

1. Const version int = 3
2. const version int := 3
3. const version int = 3 CORRECT

1: "C"onst should be just "c"onst.

Which code below is correct?

1. s := "pick me"; const length = len(s)
2. const message = "pick me!"; const length = len(message) CORRECT
3. const length = utf8.RuneCountInString("pick me")

1: s not a constant.

2: len function can be used as an initial value to a constant, when the argument to len is also a constant.

3: You cannot call functions while initializing a constant.

Which explanation below is correct for the following code?

const speed = 100
porsche := speed * 3

1. speed is typeless and porsche's type is int CORRECT
2. speed's type is int and porsche's type is also int
3. speed and porsche are typeless

2: speed has no type.

3: A variable cannot be typeless.

How to fix the following code?

const spell string
spell = "Abracadabra"

1. const spell = "Abracadabra" CORRECT
2. spell := "Abracadabra"
3. var spell = "Abracadabra"

1: A constant always have to be initialized to a value. And, sometimes the type declaration is not necessary.

2-3: That's a variable not a constant.

How to fix the following code?

const total int8 = 10
x := 5

fmt.Print(total * x)

// #1 - *CORRECT*
const total = 10
x := 5

fmt.Print(total * x)

// #2
const total int64 = 10
x := 5

fmt.Print(total * x)

// #3
const total int64 = 10
x := 5

fmt.Print(int64(total) * x)

1: Now, the total constant is typeless, so it can be used with the x variable.

2: There's still a type mismatch. x is int not int64.

3: total is already int64. No need to convert it again.

What are the values of the following constants?

const (
    Yes = (iota * 5) + 2
    No
    Both
)

1. Yes=0 No=1 Both=2
2. Yes=2 No=3 Both=4
3. Yes=7 No=12 Both=17
4. Yes=2 No=7 Both=12 CORRECT

3: iota starts at 0, not 1.