add: if statement exercises

11-if/exercises/01-age-seasons/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: Age Seasons
+//
+//  Let's start simple. Print the expected outputs,
+//  depending on the age variable.
+//
+// EXPECTED OUTPUT
+//  If age is greater than 60, print:
+//    Getting older
+//  If age is greater than 30, print:
+//    Getting wiser
+//  If age is greater than 20, print:
+//    Adulthood
+//  If age is greater than 10, print:
+//    Young blood
+//  Otherwise, print:
+//    Booting up
+// ---------------------------------------------------------
+
+func main() {
+	// Change this accordingly to produce the expected outputs
+	// age := 10
+
+	// Type your if statement here.
+}

11-if/exercises/01-age-seasons/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() {
+	age := 10
+
+	if age > 60 {
+		fmt.Println("Getting older")
+	} else if age > 30 {
+		fmt.Println("Getting wiser")
+	} else if age > 20 {
+		fmt.Println("Adulthood")
+	} else if age > 10 {
+		fmt.Println("Young blood")
+	} else {
+		fmt.Println("Booting up")
+	}
+}

11-if/exercises/02-simplify-it/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: Simplify It
+//
+//  Can you simplify the if statement inside the code below?
+//
+//  When:
+//    isSphere == true and
+//    radius is equal or greater than 200
+//
+//    It will print "It's a big sphere."
+//
+//    Otherwise, it will print "I don't know."
+//
+// EXPECTED OUTPUT
+//  It's a big sphere.
+// ---------------------------------------------------------
+
+func main() {
+	// DO NOT TOUCH THIS
+	isSphere, radius := true, 100
+
+	var big bool
+
+	if radius >= 50 {
+		if radius >= 100 {
+			if radius >= 200 {
+				big = true
+			}
+		}
+	}
+
+	if big != true {
+		fmt.Println("I don't know.")
+	} else if !(isSphere == false) {
+		fmt.Println("It's a big sphere.")
+	} else {
+		fmt.Println("I don't know.")
+	}
+}

11-if/exercises/02-simplify-it/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() {
+	isSphere, radius := true, 200
+
+	if isSphere && radius >= 200 {
+		fmt.Println("It's a big sphere.")
+	} else {
+		fmt.Println("I don't know.")
+	}
+}

11-if/exercises/03-arg-count/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: Arg Count
+//
+//  1. Get arguments from command-line.
+//  2. Print the expected outputs below depending on the number
+//     of arguments.
+//
+// EXPECTED OUTPUT
+//  go run main.go
+//    Give me args
+//
+//  go run main.go hello
+//    There is one: "hello"
+//
+//  go run main.go hi there
+//    There are two: "hi there"
+//
+//  go run main.go i wanna be a gopher
+//    There are 5 arguments
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/03-arg-count/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"
+	"os"
+)
+
+func main() {
+	var (
+		args = os.Args
+		l    = len(args) - 1
+	)
+
+	if l == 0 {
+		fmt.Println("Give me args")
+	} else if l == 1 {
+		fmt.Printf("There is one: %q\n", args[1])
+	} else if l == 2 {
+		fmt.Printf(
+			`There are two: "%s %s"`+"\n",
+			args[1], args[2],
+		)
+	} else {
+		fmt.Printf("There are %d arguments\n", l)
+	}
+}

11-if/exercises/04-vowel-or-cons/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: Vowel or Consonant
+//
+//  Detect whether a letter is vowel or consonant.
+//
+// NOTE
+//  y or w is called a semi-vowel.
+//  Check out: https://en.oxforddictionaries.com/explore/is-the-letter-y-a-vowel-or-a-consonant/
+//
+// HINT
+//  + You can find the length of an argument using the len function.
+//
+//  + len(os.Args[1]) will give you the length of the 1st argument.
+//
+// BONUS
+//  Use strings.IndexAny function to detect the vowels.
+//  Search on Google for: golang pkg strings IndexAny
+//
+// EXPECTED OUTPUT
+//  go run main.go
+//    Give me a letter
+//
+//  go run main.go hey
+//    Give me a letter
+//
+//  go run main.go a
+//    "a" is a vowel.
+//
+//  go run main.go y
+//    "y" is sometimes a vowel, sometimes not.
+//
+//  go run main.go w
+//    "w" is sometimes a vowel, sometimes not.
+//
+//  go run main.go x
+//    "x" is a consonant.
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/04-vowel-or-cons/solution/main.go

@@ -0,0 +1,34 @@
+// 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) != 2 || len(args[1]) != 1 {
+		fmt.Println("Give me a letter")
+		return
+	}
+
+	// I didn't use a short-if here because, it's already
+	// hard to read. Do not make it harder.
+
+	s := args[1]
+	if s == "a" || s == "e" || s == "i" || s == "o" || s == "u" {
+		fmt.Printf("%q is a vowel.\n", s)
+	} else if s == "w" || s == "y" {
+		fmt.Printf("%q is sometimes a vowel, sometimes not.\n", s)
+	} else {
+		fmt.Printf("%q is a consonant.\n", s)
+	}
+}

11-if/exercises/04-vowel-or-cons/solution2/main.go

@@ -0,0 +1,39 @@
+// 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"
+	"strings"
+)
+
+func main() {
+	args := os.Args
+
+	if len(args) != 2 || len(args[1]) != 1 {
+		fmt.Println("Give me a letter")
+		return
+	}
+
+	s := args[1]
+	if strings.IndexAny(s, "aeiou") != -1 {
+		fmt.Printf("%q is a vowel.\n", s)
+	} else if s == "w" || s == "y" {
+		fmt.Printf("%q is sometimes a vowel, sometimes not.\n", s)
+	} else {
+		fmt.Printf("%q is a consonant.\n", s)
+	}
+
+	// Notice that:
+	//
+	// I didn't use IndexAny for the else if above.
+	//
+	// It's because, calling a function is a costly operation.
+	// And, this way, the code is simpler.
+}

11-if/exercises/05-movie-ratings/main.go

@@ -0,0 +1,55 @@
+// 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
+
+// ---------------------------------------------------------
+// STORY
+//
+//  Your boss wants you to create a program that will check
+//  whether a person can watch a particular movie or not.
+//
+//  Imagine that another program provides the age to your
+//  program. Depending on what you return, the other program
+//  will issue the tickets to the person automatically.
+//
+// EXERCISE: Movie Ratings
+//
+//  1. Get the age from the command-line.
+//
+//  2. Return one of the following messages if the age is:
+//     -> Above 17         : "R-Rated"
+//     -> Between 13 and 17: "PG-13"
+//     -> Below 13         : "PG-Rated"
+//
+// RESTRICTIONS:
+//  1. If age data is wrong or absent let the user know.
+//  2. Do not accept negative age.
+//
+// BONUS:
+//  1. BONUS: Use if statements only twice throughout your program.
+//  2. BONUS: Use an if statement only once.
+//
+// EXPECTED OUTPUT
+//  go run main.go 18
+//    R-Rated
+//
+//  go run main.go 17
+//    PG-13
+//
+//  go run main.go 12
+//    PG-Rated
+//
+//  go run main.go
+//    Requires age
+//
+//  go run main.go -5
+//    Wrong age: "-5"
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/05-movie-ratings/solution/main.go

@@ -0,0 +1,34 @@
+// 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 len(os.Args) != 2 {
+		fmt.Println("Requires age")
+		return
+	}
+
+	age, err := strconv.Atoi(os.Args[1])
+
+	if err != nil || age < 0 {
+		fmt.Printf(`Wrong age: %q`+"\n", os.Args[1])
+		return
+	} else if age > 17 {
+		fmt.Println("R-Rated")
+	} else if age >= 13 && age <= 17 {
+		fmt.Println("PG-13")
+	} else if age < 13 {
+		fmt.Println("PG-Rated")
+	}
+}

11-if/exercises/05-movie-ratings/solution2/main.go

@@ -0,0 +1,34 @@
+// 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"
+)
+
+// 🛑 DON'T DO THIS:
+//     It's hard to read.
+//     It's just an exercise.
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Requires age")
+		return
+	} else if age, err := strconv.Atoi(os.Args[1]); err != nil || age < 0 {
+		fmt.Printf(`Wrong age: %q`+"\n", os.Args[1])
+		return
+	} else if age > 17 {
+		fmt.Println("R-Rated")
+	} else if age >= 13 && age <= 17 {
+		fmt.Println("PG-13")
+	} else if age < 13 {
+		fmt.Println("PG-Rated")
+	}
+}

11-if/exercises/06-odd-even/main.go

@@ -0,0 +1,39 @@
+// 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: Odd or Even
+//
+//  1. Get a number from the command-line.
+//
+//  2. Find whether the number is odd, even and divisible by 8.
+//
+// RESTRICTION
+//  Handle the error. If the number is not a valid number,
+//  or it's not provided, let the user know.
+//
+// EXPECTED OUTPUT
+//  go run main.go 16
+//    16 is an even number and it's divisible by 8
+//
+//  go run main.go 4
+//    4 is an even number
+//
+//  go run main.go 3
+//    3 is an odd number
+//
+//  go run main.go
+//    Pick a number
+//
+//  go run main.go ABC
+//    "ABC" is not a number
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/06-odd-even/solution/main.go

@@ -0,0 +1,35 @@
+// 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 len(os.Args) != 2 {
+		fmt.Println("Pick a number")
+		return
+	}
+
+	n, err := strconv.Atoi(os.Args[1])
+	if err != nil {
+		fmt.Printf("%q is not a number\n", os.Args[1])
+		return
+	}
+
+	if n%8 == 0 {
+		fmt.Printf("%d is an even number and it's divisible by 8\n", n)
+	} else if n%2 == 0 {
+		fmt.Printf("%d is an even number\n", n)
+	} else {
+		fmt.Printf("%d is an odd number\n", n)
+	}
+}

11-if/exercises/07-leap-year/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
+
+// ---------------------------------------------------------
+// EXERCISE: Leap Year
+//
+//  Find out whether a given year is a leap year or not.
+//
+// EXPECTED OUTPUT
+//  go run main.go
+//    Give me a year number
+//
+//  go run main.go eighties
+//    "eighties" is not a valid year.
+//
+//  go run main.go 2018
+//    2018 is not a leap year.
+//
+//  go run main.go 2019
+//    2019 is not a leap year.
+//
+//  go run main.go 2020
+//    2020 is a leap year.
+//
+//  go run main.go 2024
+//    2024 is a leap year.
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/07-leap-year/solution/main.go

@@ -0,0 +1,46 @@
+// 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 len(os.Args) != 2 {
+		fmt.Println("Give me a year number")
+		return
+	}
+
+	year, err := strconv.Atoi(os.Args[1])
+	if err != nil {
+		fmt.Printf("%q is not a valid year.\n", os.Args[1])
+		return
+	}
+
+	// Notice that:
+	// I've intentionally created this solution as verbose
+	// as I can.
+	//
+	// See the next exercise.
+
+	var leap bool
+	if year%400 == 0 {
+		leap = true
+	} else if year%4 == 0 {
+		leap = true
+	}
+
+	if leap {
+		fmt.Printf("%d is a leap year.\n", year)
+	} else {
+		fmt.Printf("%d is not a leap year.\n", year)
+	}
+}

11-if/exercises/08-simplify-leap-year/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: Simplify the Leap Year
+//
+//  1. Look at the solution of "the previous exercise".
+//
+//  2. And simplify the code (especially the if statements!).
+//
+// EXPECTED OUTPUT
+//  It's the same as the previous exercise.
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/08-simplify-leap-year/solution/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
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Give me a year number")
+		return
+	}
+
+	year, err := strconv.Atoi(os.Args[1])
+	if err != nil {
+		fmt.Printf("%q is not a valid year.\n", os.Args[1])
+		return
+	}
+
+	if year%4 == 0 && (year%100 != 0 || year%400 == 0) {
+		fmt.Printf("%d is a leap year.\n", year)
+	} else {
+		fmt.Printf("%d is not a leap year.\n", year)
+	}
+}
+
+// Review the original source code here:
+// https://github.com/golang/go/blob/ad644d2e86bab85787879d41c2d2aebbd7c57db8/src/time/time.go#L1289

11-if/exercises/09-days-in-month/main.go

@@ -0,0 +1,90 @@
+// 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: Days in a Month
+//
+//  Print the number of days in a given month.
+//
+// RESTRICTIONS
+//  1. On a leap year, february should print 29. Otherwise, 28.
+//
+//     Set your computer clock to 2020 to see whether it works.
+//
+//  2. It should work case-insensitive. See below.
+//
+//     Search on Google: golang pkg strings ToLower
+//
+//  3. Get the current year using the time.Now()
+//
+//     Search on Google: golang pkg time now year
+//
+//
+// EXPECTED OUTPUT
+//
+//  -----------------------------------------
+//  Your solution should not accept invalid months
+//  -----------------------------------------
+//  go run main.go
+//    Give me a month name
+//
+//  go run main.go sheep
+//    "sheep" is not a month.
+//
+//  go run main.go january
+//    "january" has 31 days.
+//
+//  -----------------------------------------
+//  Your solution should handle the leap years
+//  -----------------------------------------
+//  go run main.go february
+//    "february" has 28 days.
+//
+//  go run main.go march
+//    "march" has 31 days.
+//
+//  go run main.go april
+//    "april" has 30 days.
+//
+//  go run main.go may
+//    "may" has 31 days.
+//
+//  go run main.go june
+//    "june" has 30 days.
+//
+//  go run main.go july
+//    "july" has 31 days.
+//
+//  go run main.go august
+//    "august" has 31 days.
+//
+//  go run main.go september
+//    "september" has 30 days.
+//
+//  go run main.go october
+//    "october" has 31 days.
+//
+//  go run main.go november
+//    "november" has 30 days.
+//
+//  go run main.go december
+//    "december" has 31 days.
+//
+//  -----------------------------------------
+//  Your solution should be case insensitive
+//  -----------------------------------------
+//  go run main.go DECEMBER
+//    "DECEMBER" has 31 days.
+//
+//  go run main.go dEcEmBeR
+//    "dEcEmBeR" has 31 days.
+// ---------------------------------------------------------
+
+func main() {
+}

11-if/exercises/09-days-in-month/solution/main.go

@@ -0,0 +1,58 @@
+// 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"
+	"strings"
+	"time"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Give me a month name")
+		return
+	}
+
+	// get the current year and find out whether it's a leap year
+	year := time.Now().Year()
+	leap := year%4 == 0 && (year%100 != 0 || year%400 == 0)
+
+	// setting it to 28, saves me typing it below again
+	days := 28
+
+	month := os.Args[1]
+
+	// case insensitive
+	if m := strings.ToLower(month); m == "april" ||
+		m == "june" ||
+		m == "september" ||
+		m == "november" {
+		days = 30
+	} else if m == "january" ||
+		m == "march" ||
+		m == "may" ||
+		m == "july" ||
+		m == "august" ||
+		m == "october" ||
+		m == "december" {
+		days = 31
+	} else if m == "february" {
+		// try a "logical and operator" above.
+		// like: `else if m == "february" && leap`
+		if leap {
+			days = 29
+		}
+	} else {
+		fmt.Printf("%q is not a month.\n", month)
+		return
+	}
+
+	fmt.Printf("%q has %d days.\n", month, days)
+}

11-if/exercises/README.md

@@ -0,0 +1,22 @@
+# If Statement
+
+1. **[Age Seasons](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/01-age-seasons)**
+
+2. **[Simplify It](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/02-simplify-it)**
+
+3. **[Arg Count](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/03-arg-count)**
+
+4. **[Vowel or Consonant](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/04-vowel-or-cons)**
+
+## Error Handling
+
+5. **[Movie Ratings](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/05-movie-ratings)**
+
+6. **[Odd or Even](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/06-odd-even)**
+
+7. **[Leap Year](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/07-leap-year)**
+
+8. **[Simplify the Leap Year](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/08-simplify-leap-year)**
+
+9. **[Days in a Month](https://github.com/inancgumus/learngo/tree/master/11-if/exercises/09-days-in-month)**
+

12-switch/exercises/README.md

@@ -0,0 +1,11 @@
+# Header
+
+What you will learn?
+
+1. **[text](https://github.com/inancgumus/learngo/tree/master/)**
+
+    text
+
+2. **[text](https://github.com/inancgumus/learngo/tree/master/)**
+
+    text