Initial commit

06-variables/02-declarations/01-declaration-syntax/01-syntax/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var speed int
+
+	fmt.Println(speed)
+}

06-variables/02-declarations/01-declaration-syntax/02-naming-rules/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// VARIABLE NAMING RULES
+
+func main() {
+	// CORRECT DECLARATIONS
+	var speed int
+	var SpeeD int
+
+	// underscore is allowed but not recommended
+	var _speed int
+
+	// unicode letters are allowed
+	var 速度 int
+
+	// keep the compiler happy
+	_, _, _, _ = speed, SpeeD, _speed, 速度
+}

06-variables/02-declarations/01-declaration-syntax/03-order-of-declaration/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	// fmt.Println(speed)
+	// var speed int
+}

06-variables/02-declarations/02-example-declarations/01-int/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var nFiles int
+	var counter int
+	var nCPU int
+
+	fmt.Println(
+		nFiles,
+		counter,
+		nCPU,
+	)
+}

06-variables/02-declarations/02-example-declarations/02-float64/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var heat float64
+	var ratio float64
+	var degree float64
+
+	fmt.Println(
+		heat,
+		ratio,
+		degree,
+	)
+}

06-variables/02-declarations/02-example-declarations/03-bool/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var off bool
+	var valid bool
+	var closed bool
+
+	fmt.Println(
+		off,
+		valid,
+		closed,
+	)
+}

06-variables/02-declarations/02-example-declarations/04-string/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var msg string
+	var name string
+	var text string
+
+	fmt.Println(
+		msg,
+		name,
+		text,
+	)
+}

06-variables/02-declarations/03-zero-values/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+// EXERCISE: Let's run this to see the zero-values yourself
+
+func main() {
+	var speed int    // numeric type
+	var heat float64 // numeric type
+	var off bool
+	var brand string
+
+	fmt.Println(speed)
+	fmt.Println(heat)
+	fmt.Println(off)
+
+	// I've used printf to print an empty string
+	// EXERCISE: Use Println to see what happens
+	fmt.Printf("%q\n", brand)
+}

06-variables/02-declarations/04-unused-variables-and-blank-identifier/01-unused-variable/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// there's no warning for package-level vars
+var packageLevelVar string
+
+func main() {
+	// unused variable error
+	// var speed int
+
+	// if you use it, the error will be gone
+	// fmt.Println(speed)
+}

06-variables/02-declarations/04-unused-variables-and-blank-identifier/02-blank-identifier/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	var speed int
+
+	// let's assign the variable to the blank-identifier
+	// so that Go compiler won't get grumpy
+	_ = speed
+}

06-variables/02-declarations/05-multiple-declarations/01-multiple/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var (
+		speed int
+		heat  float64
+
+		off   bool
+		brand string
+	)
+
+	fmt.Println(speed)
+	fmt.Println(heat)
+	fmt.Println(off)
+	fmt.Printf("%q\n", brand)
+}

06-variables/02-declarations/05-multiple-declarations/02-parallel/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	// this is equal to:
+	//
+	//   var (
+	//     speed int
+	//     velocity int
+	//   )
+	//
+	// or:
+	//
+	//   var speed int
+	//   var velocity int
+	//
+	var speed, velocity int
+
+	fmt.Println(speed, velocity)
+}

06-variables/02-declarations/06-examples/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	// names are case-sensitive:
+	// MyAge, myAge, and MYAGE are different variables
+
+	// USE-CASE:
+	// When to use a parallel declaration?
+	//
+	// NOT GOOD:
+	// var myAge int
+	// var yourAge int
+	//
+	// SO-SO:
+	// var (
+	// 	myAge int
+	// 	yourAge int
+	// )
+	//
+	// BETTER:
+	var myAge, yourAge int
+	fmt.Println(myAge, yourAge)
+
+	var temperature float64
+	fmt.Println(temperature)
+
+	var success bool
+	fmt.Println(success)
+
+	var language string
+	fmt.Println(language)
+}

06-variables/02-declarations/exercises/01/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare and print a variable with an int type
+//  2- The declared variable's name should be: height
+//
+// EXPECTED OUTPUT
+//  0
+// ---------------------------------------------------------
+
+func main() {
+	// var ? ?
+	// ?
+}

06-variables/02-declarations/exercises/01/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	var height int
+
+	fmt.Println(height)
+}

06-variables/02-declarations/exercises/02/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// OPTIONAL EXERCISE
+//  1- Declare and print a bool variable
+//  2- The variable's name should be: isOn
+//
+// EXPECTED OUTPUT
+//  false
+// ---------------------------------------------------------
+
+func main() {
+	// var ? ?
+	// ?
+}

06-variables/02-declarations/exercises/02/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	var isOn bool
+	fmt.Println(isOn)
+}

06-variables/02-declarations/exercises/03/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare and print a variable with a float64 type
+//  2- The declared variable's name should be: brightness
+//
+// EXPECTED OUTPUT
+//  0
+// ---------------------------------------------------------
+
+func main() {
+	// var ? ?
+	// ?
+}

06-variables/02-declarations/exercises/03/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	var brightness int
+
+	fmt.Println(brightness)
+}

06-variables/02-declarations/exercises/04/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare a string variable
+//  2- Print that variable
+//
+// EXPECTED OUTPUT
+//  ""
+// ---------------------------------------------------------
+
+func main() {
+	// USE THE BELOW CODE
+	// You'll learn about Printf later
+
+	// var ?
+	// fmt.Printf("s (%T): %q\n", s, s)
+
+	// %T prints the type of the value
+	// %q prints an empty string
+}

06-variables/02-declarations/exercises/04/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var s string
+	fmt.Printf("s (%T): %q\n", s, s)
+}

06-variables/02-declarations/exercises/05/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare the variables below:
+//      3speed
+//      !speed
+//      spe?ed
+//      var
+//      func
+//      package
+//
+//  2- Observe the error messages
+//
+// NOTE
+//   The types of the variables are not important.
+// ---------------------------------------------------------
+
+func main() {
+	// var ? int
+	// var ? int
+	// var ? int
+	// var ? int
+	// var ? int
+	// var ? int
+}

06-variables/02-declarations/exercises/05/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	// var 3speed int
+	// var !speed int
+	// var spe?ed int
+	// var var int
+	// var func int
+	// var package int
+}

06-variables/02-declarations/exercises/06/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare a few variables using the following types
+//    int
+//    int8
+//    int16
+//    int32
+//    int64
+//    float32
+//    float64
+//    complex64
+//    complex128
+//    bool
+//    string
+//    rune
+//    byte
+//
+// 2- Observe their output
+// 3- After you've done, check out the solution
+//    and read the comments there
+//
+// EXPECTED OUTPUT
+//  0 0 0 0 0 0 0 false 0 0
+//  ""
+// ---------------------------------------------------------
+
+func main() {
+	// var i int
+	// var i8 int8
+
+	// CONTINUE FROM HERE....
+}

06-variables/02-declarations/exercises/06/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	// integer types
+	var i int
+	var i8 int8
+	var i16 int16
+	var i32 int32
+	var i64 int64
+
+	// float types
+	var f32 float32
+	var f64 float64
+
+	// bool type
+	var b bool
+
+	// string types
+	var s string
+	var r rune  // also a numeric type
+	var by byte // also a numeric type
+
+	fmt.Println(
+		i, i8, i16, i32, i64,
+		f32, f64,
+		b, r, by,
+	)
+
+	// You could do it with Println as well
+	fmt.Printf("%q\n", s)
+}

06-variables/02-declarations/exercises/07/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1. Declare two variables using
+//     multiple variable declaration statement
+//
+//  2. The first variable's name should be active
+//  3. The second variable's name should be delta
+//
+//  4. Print them all
+//
+// HINT
+//  You should declare a bool and an int variable
+//
+// EXPECTED OUTPUT
+//  false 0
+// ---------------------------------------------------------
+
+func main() {
+	// var (
+	//   ?
+	// )
+	// fmt.Println(active, delta)
+}

06-variables/02-declarations/exercises/07/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var (
+		active bool
+		delta  int
+	)
+	fmt.Println(active, delta)
+}

06-variables/02-declarations/exercises/08/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1. Declare and initialize two string variables
+//     using multiple variable declaration
+//
+//  2. Use the type once while declaring the variables
+//
+//  3. The first variable's name should be firstName
+//  4. The second variable's name should be lastName
+//
+//  5. Print them all
+//
+// EXPECTED OUTPUT
+//  "" ""
+// ---------------------------------------------------------
+
+func main() {
+	// ADD YOUR DECLARATION HERE
+	//
+
+	// REPLACE THE QUESTION-MARKS BELOW
+	// WITH THE NAME OF YOUR VARIABLES
+
+	// fmt.Printf("%q %q\n", ?, ?)
+}

06-variables/02-declarations/exercises/08/solution/main.go

@@ -0,0 +1,15 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import "fmt"
+
+func main() {
+	var firstName, lastName string = "", ""
+	fmt.Printf("%q %q\n", firstName, lastName)
+}

06-variables/02-declarations/exercises/09/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare a variable
+//  2- Variable's name should be: isLiquid
+//  3- Discard it using a blank-identifier
+//
+// NOTE
+//  Do not print the variable
+// ---------------------------------------------------------
+
+func main() {
+}

06-variables/02-declarations/exercises/09/solution/main.go

@@ -0,0 +1,13 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	var isLiquid bool
+	_ = isLiquid
+}

06-variables/02-declarations/exercises/10/main.go

@@ -0,0 +1,19 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Declare a variable in the package-scope
+//
+//  2- Observe whether something happens when you don't
+//     use it
+// ---------------------------------------------------------
+
+func main() {
+}

06-variables/02-declarations/exercises/10/solution/main.go

@@ -0,0 +1,13 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+var isLiquid bool
+
+func main() {
+}

06-variables/02-declarations/exercises/11/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE
+//  1- Print a variable
+//  2- Then declare it
+//  (This means: Try to print it before its declaration)
+//  3- Observe the error
+// ---------------------------------------------------------
+
+func main() {
+	// First print it:
+	// fmt.Println(?)
+
+	// Then declare it:
+	// var ? ?
+}

06-variables/02-declarations/exercises/11/solution/main.go

@@ -0,0 +1,15 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	// UNCOMMENT THE CODE BELOW TO SEE THE ERROR
+
+	// fmt.Println(age)
+	// var age int
+}

06-variables/02-declarations/questions/01-what.md

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+# QUESTIONS: What's a variable?
+
+* **Where does a variable live?**
+* Hard Disk
+* Computer Memory - *CORRECT*
+* CPU
+
+* **What do you use a variable's name for?**
+* To be able to access it later - *CORRECT*
+* It's just a label
+* I don't need to use it
+
+* **How to change the value of a variable?**
+* By using its name - *CORRECT*
+* By using its value
+* By asking to Go
+ 
+* **After its declaration can you change the variable's type?**
+* Yes : Go is dynamically-typed
+* No  : Go is statically-typed - *CORRECT*
+* Both: Go supports both of them
+

06-variables/02-declarations/questions/02-declaration.md

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+## Which statement do you need to use for declaring variables?
+* name int
+* vars string name
+* var name integer
+* var width int *CORRECT*
+
+## Which sentence below is correct?
+* You can use a variable before declaring it
+* You have to declare a variable before using it *CORRECT*
+
+## What kind of language is Go?
+* Weakly-Typed
+* Dynamically-Typed
+* Strongly-Typed *CORRECT*
+* Freely-Typed
+
+## Which variable name below is correct?
+* int
+* four *CORRECT*
+* 2computers
+* one?there

06-variables/02-declarations/questions/03-unused-variables.md

@@ -0,0 +1,14 @@
+## What happens when you don't use a declared variable in the block scope?
+* Nothing, it will work fine
+* It will get removed automatically
+* The program won't compile *CORRECT*
+
+## What happens when you don't use a declared variable in the package scope?
+* Nothing, it will work fine *CORRECT*
+* It will get removed automatically
+* The program won't compile
+
+## How can you prevent unused variable error?
+* You can change the variable's name
+* You can use a blank-identifier to discard it *CORRECT*
+* You can change the variable's type

06-variables/02-declarations/questions/04-zero-values.md

@@ -0,0 +1,23 @@
+## Which type's zero value is 0?
+- bool
+- pointer
+- string
+- all numeric types *CORRECT*
+
+## Which type's zero value is false?
+- bool *CORRECT*
+- pointer
+- string
+- all numeric types
+
+## Which type's zero value is ""?
+- bool
+- pointer
+- string *CORRECT*
+- all numeric types
+
+## Which type's zero value is nil?
+- bool
+- pointer *CORRECT*
+- string
+- all numeric types