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10-constants/questions/questions.md

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+## 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`
+2. `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?
+```go
+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?
+```go
+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?
+```go
+const total int8 = 10
+x := 5
+
+fmt.Print(total * x)
+```
+
+```go
+// #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?
+```go
+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.