Initial commit

11-if/01-boolean-operators/01-comparison-operators/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() {
+	speed := 100 // #1
+	// speed := 10 // #2
+
+	fast := speed >= 80
+	slow := speed < 20
+
+	fmt.Printf("fast's type is %T\n", fast)
+
+	fmt.Printf("going fast? %t\n", fast)
+	fmt.Printf("going slow? %t\n", slow)
+
+	fmt.Printf("is it 100 mph? %t\n", speed == 100)
+	fmt.Printf("is it not 100 mph? %t\n", speed != 100)
+}

11-if/01-boolean-operators/02-comparison-and-assignability/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
+
+func main() {
+	var speed int
+	// speed = "100" // NOT OK
+
+	var running bool
+	// running = 50 // NOT OK
+
+	var force float64
+	// speed = force // NOT OK
+
+	_, _, _ = speed, running, force
+}

11-if/01-boolean-operators/02-comparison-and-assignability/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
+
+func main() {
+	var speed int
+	speed = 50 // OK
+
+	var running bool
+	running = true // OK
+
+	var force float64
+	speed = int(force)
+
+	_, _, _ = speed, running, force
+}

11-if/01-boolean-operators/02-comparison-and-assignability/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
+
+import (
+	"fmt"
+	"strings"
+)
+
+func main() {
+	speed := 100 // #1
+	// speed := 10 // #2
+
+	fast := speed >= 80
+	slow := speed < 20
+
+	fmt.Printf("going fast? %t\n", fast)
+	fmt.Printf("going slow? %t\n", slow)
+
+	fmt.Printf("is it 100 mph? %t\n", speed == 100)
+	fmt.Printf("is it not 100 mph? %t\n", speed != 100)
+
+	fmt.Println(strings.Repeat("-", 25))
+
+	// -------------------------
+	// #3
+	speedB := 150.5
+	faster := speedB > 100 // ok: untyped
+
+	fmt.Println("is the other car going faster?", faster)
+
+	// ERROR: Type Mismatch
+	// faster = speedB > speed
+	faster = speedB > float64(speed)
+	fmt.Println("is the other car going faster?", faster)
+
+	// #4
+	// ERROR:
+	// only numeric values are comparable with
+	// ordering operators: <, <=, >, >=
+
+	// fmt.Println(true > faster)
+}

11-if/01-boolean-operators/03-logical-operators/01-and-operator/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
+
+import "fmt"
+
+func main() {
+	// remove the comments and run
+	// i've commented the lines it's because of the warnings
+
+	// fmt.Println("true  && true  =", true && true)
+	fmt.Println("true  && false =", true && false)
+	fmt.Println("false && true  =", false && true)
+	// fmt.Println("false && false =", false && false)
+}

11-if/01-boolean-operators/03-logical-operators/01-and-operator/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
+
+import "fmt"
+
+func main() {
+	speed := 100
+	fmt.Println("within limits?",
+		speed >= 40 && speed <= 55,
+	)
+
+	speed = 20
+	fmt.Println("within limits?",
+		speed >= 40 && speed <= 55,
+		// ^- short-circuits in the first expression here
+		//    because, it becomes false
+	)
+
+	speed = 50
+	fmt.Println("within limits?",
+		speed >= 40 && speed <= 55,
+	)
+
+	// ERROR: invalid
+	// both operands should be booleans
+	// 1 && 2
+	fmt.Println(1 == 1 && 2 == 2)
+}

11-if/01-boolean-operators/03-logical-operators/02-or-operator/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
+
+import "fmt"
+
+func main() {
+	// remove the comments and run
+	// i've commented the lines it's because of the warnings
+
+	// fmt.Println("true  || true  =", true || true)
+	fmt.Println("true  || false =", true || false)
+	fmt.Println("false || true  =", false || true)
+	// fmt.Println("false || false =", false || false)
+}

11-if/01-boolean-operators/03-logical-operators/02-or-operator/02/main.go

@@ -0,0 +1,31 @@
+// 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() {
+	color := "red"
+
+	fmt.Println("reddish colors?",
+		// true || false => true (short-circuits)
+		color == "red" || color == "dark red",
+	)
+
+	color = "dark red"
+
+	fmt.Println("reddish colors?",
+		// false || true => true
+		color == "red" || color == "dark red",
+	)
+
+	fmt.Println("greenish colors?",
+		// false || false => false
+		color == "green" || color == "light green",
+	)
+}

11-if/01-boolean-operators/03-logical-operators/03-not-operator/01/main.go

@@ -0,0 +1,18 @@
+// 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() {
+	fmt.Println(
+		"hi" == "hi" && 3 > 2,    //   true  && true  => true
+		"hi" != "hi" || 3 > 2,    //   false || true  => true
+		!("hi" != "hi" || 3 > 2), // !(false || true) => false
+	)
+}

11-if/01-boolean-operators/03-logical-operators/03-not-operator/02/main.go

@@ -0,0 +1,22 @@
+// 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 on bool
+
+	on = !on
+	fmt.Println(on)
+
+	on = !!on
+	fmt.Println(on)
+}

11-if/02-if-statement/01-if-branch/main.go

@@ -0,0 +1,18 @@
+// 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() {
+	score, valid := 5, true
+
+	if score > 3 && valid {
+		fmt.Println("good")
+	}
+}

11-if/02-if-statement/02-else-branch/main.go

@@ -0,0 +1,20 @@
+// 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() {
+	score, valid := 3, true
+
+	if score > 3 && valid {
+		fmt.Println("good")
+	} else {
+		fmt.Println("low")
+	}
+}

11-if/02-if-statement/03-else-if-branch/01/main.go

@@ -0,0 +1,22 @@
+// 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() {
+	score := 3
+
+	if score > 3 {
+		fmt.Println("good")
+	} else if score == 3 {
+		fmt.Println("on the edge")
+	} else {
+		fmt.Println("low")
+	}
+}

11-if/02-if-statement/03-else-if-branch/02/main.go

@@ -0,0 +1,24 @@
+// 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() {
+	score := 2
+
+	if score > 3 {
+		fmt.Println("good")
+	} else if score == 3 {
+		fmt.Println("on the edge")
+	} else if score == 2 {
+		fmt.Println("meh...")
+	} else {
+		fmt.Println("low")
+	}
+}

11-if/02-if-statement/04-refactor-feet-to-meters/main.go

@@ -0,0 +1,42 @@
+// 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"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const usage = `
+Feet to Meters
+--------------
+This program converts feet into meters.
+
+Usage:
+feet [feetsToConvert]`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(strings.TrimSpace(usage))
+
+		// ALTERNATIVE:
+		// fmt.Println("Please tell me a value in feet")
+
+		return
+	}
+
+	arg := os.Args[1]
+
+	feet, _ := strconv.ParseFloat(arg, 64)
+
+	meters := feet * 0.3048
+
+	fmt.Printf("%g feet is %g meters.\n", feet, meters)
+}

11-if/02-if-statement/05-challenge-userpass/01-1st-challenge/01-challenge/main.go

@@ -0,0 +1,36 @@
+// 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
+
+// ---------------------------------------------------------
+// CHALLENGE #1
+//  Create a user/password protected program.
+//
+// EXAMPLE USER
+//  username: jack
+//  password: 1888
+//
+// EXPECTED OUTPUT
+//  go run main.go
+//    Usage: [username] [password]
+//
+//  go run main.go albert
+//    Usage: [username] [password]
+//
+//  go run main.go hacker 42
+//    Access denied for "hacker".
+//
+//  go run main.go jack 6475
+//    Invalid password for "jack".
+//
+//  go run main.go jack 1888
+//    Access granted to "jack".
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/02-if-statement/05-challenge-userpass/01-1st-challenge/02-solution/main.go

@@ -0,0 +1,32 @@
+// 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"
+	"os"
+)
+
+func main() {
+	args := os.Args
+
+	if len(args) != 3 {
+		fmt.Println("Usage: [username] [password]")
+		return
+	}
+
+	u, p := args[1], args[2]
+
+	if u != "jack" {
+		fmt.Printf("Access denied for %q.\n", u)
+	} else if p != "1888" {
+		fmt.Printf("Invalid password for %q.\n", u)
+	} else {
+		fmt.Printf("Access granted to %q.\n", u)
+	}
+}

11-if/02-if-statement/05-challenge-userpass/01-1st-challenge/03-solution-refactor/main.go

@@ -0,0 +1,41 @@
+// 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"
+	"os"
+)
+
+const (
+	usage    = "Usage: [username] [password]"
+	errUser  = "Access denied for %q.\n"
+	errPwd   = "Invalid password for %q.\n"
+	accessOK = "Access granted to %q.\n"
+	user     = "jack"
+	pass     = "1888"
+)
+
+func main() {
+	args := os.Args
+
+	if len(args) != 3 {
+		fmt.Println(usage)
+		return
+	}
+
+	u, p := args[1], args[2]
+
+	if u != user {
+		fmt.Printf(errUser, u)
+	} else if p != pass {
+		fmt.Printf(errPwd, u)
+	} else {
+		fmt.Printf(accessOK, u)
+	}
+}

11-if/02-if-statement/05-challenge-userpass/02-2nd-challenge/01-challenge/main.go

@@ -0,0 +1,72 @@
+// 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"
+	"os"
+)
+
+// ---------------------------------------------------------
+// CHALLENGE #2
+//  Add one more user to the PassMe program below.
+//
+// EXAMPLE USERS
+//  username: jack
+//  password: 1888
+//
+//  username: inanc
+//  password: 1879
+//
+// EXPECTED OUTPUT
+//  go run main.go
+//    Usage: [username] [password]
+//
+//  go run main.go hacker 42
+//    Access denied for "hacker".
+//
+//  go run main.go jack 1888
+//    Access granted to "jack".
+//
+//  go run main.go inanc 1879
+//    Access granted to "inanc".
+//
+//  go run main.go jack 1879
+//    Invalid password for "jack".
+//
+//  go run main.go inanc 1888
+//    Invalid password for "inanc".
+// ---------------------------------------------------------
+
+const (
+	usage    = "Usage: [username] [password]"
+	errUser  = "Access denied for %q.\n"
+	errPwd   = "Invalid password for %q.\n"
+	accessOK = "Access granted to %q.\n"
+	user     = "jack"
+	pass     = "1888"
+)
+
+func main() {
+	args := os.Args
+
+	if len(args) != 3 {
+		fmt.Println(usage)
+		return
+	}
+
+	u, p := args[1], args[2]
+
+	if u != user {
+		fmt.Printf(errUser, u)
+	} else if p != pass {
+		fmt.Printf(errPwd, u)
+	} else {
+		fmt.Printf(accessOK, u)
+	}
+}

11-if/02-if-statement/05-challenge-userpass/02-2nd-challenge/02-solution/main.go

@@ -0,0 +1,43 @@
+// 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"
+	"os"
+)
+
+const (
+	usage       = "Usage: [username] [password]"
+	errUser     = "Access denied for %q.\n"
+	errPwd      = "Invalid password for %q.\n"
+	accessOK    = "Access granted to %q.\n"
+	user, user2 = "jack", "inanc"
+	pass, pass2 = "1888", "1879"
+)
+
+func main() {
+	args := os.Args
+
+	if len(args) != 3 {
+		fmt.Println(usage)
+		return
+	}
+
+	u, p := args[1], args[2]
+
+	if u != user && u != user2 {
+		fmt.Printf(errUser, u)
+	} else if u == user && p == pass {
+		fmt.Printf(accessOK, u)
+	} else if u == user2 && p == pass2 {
+		fmt.Printf(accessOK, u)
+	} else {
+		fmt.Printf(errPwd, u)
+	}
+}

11-if/03-error-handling/01-itoa/main.go

@@ -0,0 +1,22 @@
+// 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"
+	"strconv"
+)
+
+func main() {
+	// Itoa doesn't return any errors
+	// So, you don't have to handle the errors for it
+
+	s := strconv.Itoa(42)
+
+	fmt.Println(s)
+}

11-if/03-error-handling/02-atoi/main.go

@@ -0,0 +1,24 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// Atoi returns an error value
+	// So, you should always check it
+
+	n, err := strconv.Atoi(os.Args[1])
+
+	fmt.Println("Converted number    :", n)
+	fmt.Println("Returned error value:", err)
+}

11-if/03-error-handling/03-atoi-error-handling/main.go

@@ -0,0 +1,44 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	age := os.Args[1]
+
+	// Atoi returns an int and an error value
+	// So, you need to handle the errors
+
+	n, err := strconv.Atoi(age)
+
+	// handle the error immediately and quit
+	// don't do anything else here
+
+	if err != nil {
+		fmt.Println("ERROR:", err)
+
+		// quits/returns from the main function
+		// so, the program ends
+		return
+	}
+
+	// DO NOT DO THIS:
+	// else {
+	//   happy path
+	// }
+
+	// DO THIS:
+
+	// happy path (err is nil)
+	fmt.Printf("SUCCESS: Converted %q to %d.\n", age, n)
+}

11-if/03-error-handling/04-challenge-feet-to-meters/01-challenge/main.go

@@ -0,0 +1,52 @@
+// 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"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// ---------------------------------------------------------
+// CHALLENGE
+//  Add error handling to the feet to meters program.
+//
+// EXPECTED OUTPUT
+//  go run main.go hello
+//    error: 'hello' is not a number.
+//
+//  go run main.go what
+//    error: 'what' is not a number.
+//
+//  go run main.go 100
+//    100 feet is 30.48 meters.
+// ---------------------------------------------------------
+
+const usage = `
+Feet to Meters
+--------------
+This program converts feet into meters.
+
+Usage:
+feet [feetsToConvert]`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(strings.TrimSpace(usage))
+		return
+	}
+
+	arg := os.Args[1]
+
+	feet, _ := strconv.ParseFloat(arg, 64)
+	meters := feet * 0.3048
+
+	fmt.Printf("%g feet is %g meters.\n", feet, meters)
+}

11-if/03-error-handling/04-challenge-feet-to-meters/02-solution/main.go

@@ -0,0 +1,42 @@
+// 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"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const usage = `
+Feet to Meters
+--------------
+This program converts feet into meters.
+
+Usage:
+feet [feetsToConvert]`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(strings.TrimSpace(usage))
+		return
+	}
+
+	arg := os.Args[1]
+
+	feet, err := strconv.ParseFloat(arg, 64)
+	if err != nil {
+		fmt.Printf("error: '%s' is not a number.\n", arg)
+		return
+	}
+
+	meters := feet * 0.3048
+
+	fmt.Printf("%g feet is %g meters.\n", feet, meters)
+}

11-if/04-short-if/01-without-short-if/main.go

@@ -0,0 +1,21 @@
+// 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"
+	"strconv"
+)
+
+func main() {
+	n, err := strconv.Atoi("42")
+
+	if err == nil {
+		fmt.Println("There was no error, n is", n)
+	}
+}

11-if/04-short-if/02-with-short-if/main.go

@@ -0,0 +1,23 @@
+// 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"
+	"strconv"
+)
+
+func main() {
+	if n, err := strconv.Atoi("42"); err == nil {
+		// n and err are available here
+		fmt.Println("There was no error, n is", n)
+	}
+
+	// n and err are not available here
+	// fmt.Println(n, err)
+}

11-if/04-short-if/03-scope/main.go

@@ -0,0 +1,44 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if a := os.Args; len(a) != 2 {
+
+		// only a is available here
+		fmt.Println("Give me a number.")
+
+		// no need to return on error
+		// return
+
+	} else if n, err := strconv.Atoi(a[1]); err != nil {
+
+		// a, n and err are available here
+		fmt.Printf("Cannot convert %q.\n", a[1])
+
+		// no need to return on error
+		// return
+
+	} else {
+		// all of the variables (names)
+		// are available here
+		fmt.Printf("%s * 2 is %d\n", a[1], n*2)
+	}
+
+	// a, n and err are not available here
+	// they belong to the if statement
+
+	// TRY:
+	// fmt.Println(a, n, err)
+}

11-if/04-short-if/04-scope-shadowing/01-shadowing/main.go

@@ -0,0 +1,37 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// UNCOMMENT THIS TO SEE IT IN ACTION:
+	// var n int
+
+	if a := os.Args; len(a) != 2 {
+		fmt.Println("Give me a number.")
+	} else if n, err := strconv.Atoi(a[1]); err != nil {
+		// else if here shadows the main func's n
+		// variable and it declares it own
+		// with the same name: n
+
+		fmt.Printf("Cannot convert %q.\n", a[1])
+	} else {
+		fmt.Printf("%s * 2 is %d\n", a[1], n*2)
+	}
+
+	// n here belongs to the main func
+	// not to the if statement above
+
+	// UNCOMMENT ALSO LINES BELOW TO SEE IT IN ACTION:
+	// fmt.Printf("n is %d. 👻 👻 👻 - you've been shadowed ;-)", n)
+}

11-if/04-short-if/04-scope-shadowing/02-shadowing-solution/main.go

@@ -0,0 +1,44 @@
+// 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"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// n and err belongs to the main function now
+	// not only to the if statement below
+	var (
+		n   int
+		err error
+	)
+
+	if a := os.Args; len(a) != 2 {
+		fmt.Println("Give me a number.")
+	} else if n, err = strconv.Atoi(a[1]); err != nil {
+		// here else if uses the main func's n and err
+		// variables instead of its own
+
+		fmt.Printf("Cannot convert %q.\n", a[1])
+	} else {
+		// assigns the result back into main func's
+		// n variable
+		n *= 2
+
+		fmt.Printf("%s * 2 is %d\n", a[1], n)
+	}
+
+	// if statement has calculated the result using
+	// the main func's n variable
+	//
+	// so, that's why it prints the correct result here
+	fmt.Println("n is", n)
+}

11-if/exercises/00/main.go

@@ -0,0 +1,22 @@
+// 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
+//  ?
+//
+// NOTE
+//  ?
+//
+// EXPECTED OUTPUT
+//  ?
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/00/solution/main.go

@@ -0,0 +1,11 @@
+// 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() {
+}

11-if/questions/questions.md

@@ -0,0 +1,3 @@
+## ?
+* text *CORRECT*
+* text