add: func exercises

25-functions/exercises/README.md

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+# Function Exercises
+
+1. **[Refactor the Game Store to Funcs - Step #1](https://github.com/inancgumus/learngo/tree/master/25-functions/exercises/refactor-to-funcs-1)**
+
+    Remember the game store program from the structs exercises? Now, it's time to refactor it to funcs.
+
+2. **[Refactor the Game Store to Funcs - Step #2](https://github.com/inancgumus/learngo/tree/master/25-functions/exercises/refactor-to-funcs-2)**
+
+    Let's continue the refactoring from the previous exercise. This time, you're going to refactor the command handling logic.

25-functions/exercises/refactor-to-funcs-1/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/
+//
+
+// ---------------------------------------------------------
+// EXERCISE: Refactor the game store to funcs - step #1
+//
+//  Remember the game store program from the structs exercises?
+//  Now, it's time to refactor it to funcs.
+//
+//  Create games.go file
+//
+//     1- Move the structs there
+//
+//     2- Add a func that creates and returns a game.
+//
+//        Name  : newGame
+//        Inputs: id, price, name and genre
+//        Output: game
+//
+//     3- Add a func that adds a `game` to `[]game` and returns `[]game`:
+//
+//        Name  : addGame
+//        Inputs: []game, game
+//        Output: []game
+//
+//     4- Add a func that uses newGame and addGame funcs to load up the game
+//        store:
+//
+//        Name  : load
+//        Inputs: none
+//        Output: []game
+//
+//     5- Add a func that indexes games by ID:
+//
+//        Name  : indexByID
+//        Inputs: []game
+//        Output: map[int]game
+//
+//     6- Add a func that prints the given game:
+//
+//        Name  : printGame
+//        Inputs: game
+//
+//
+//  Go back to main.go and change the existing code with
+//  the new funcs that you've created. There are hints
+//  inside the code.
+//
+// ---------------------------------------------------------
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	type item struct {
+		id    int
+		name  string
+		price int
+	}
+
+	type game struct {
+		item
+		genre string
+	}
+
+	// load()
+	games := []game{
+		{
+			item:  item{id: 1, name: "god of war", price: 50},
+			genre: "action adventure",
+		},
+		{item: item{id: 2, name: "x-com 2", price: 40}, genre: "strategy"},
+		{item: item{id: 3, name: "minecraft", price: 20}, genre: "sandbox"},
+	}
+
+	// indexByID()
+	byID := make(map[int]game)
+	for _, g := range games {
+		byID[g.id] = g
+	}
+
+	fmt.Printf("Inanc's game store has %d games.\n", len(games))
+
+	in := bufio.NewScanner(os.Stdin)
+	for {
+		fmt.Printf(`
+  > list   : lists all the games
+  > id N   : queries a game by id
+  > quit   : quits
+
+`)
+
+		if !in.Scan() {
+			break
+		}
+
+		fmt.Println()
+
+		cmd := strings.Fields(in.Text())
+		if len(cmd) == 0 {
+			continue
+		}
+
+		switch cmd[0] {
+		case "quit":
+			fmt.Println("bye!")
+			return
+
+		case "list":
+			for _, g := range games {
+				// printGame()
+				fmt.Printf("#%d: %-15q %-20s $%d\n",
+					g.id, g.name, "("+g.genre+")", g.price)
+			}
+
+		case "id":
+			if len(cmd) != 2 {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			id, err := strconv.Atoi(cmd[1])
+			if err != nil {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			g, ok := byID[id]
+			if !ok {
+				fmt.Println("sorry. i don't have the game")
+				continue
+			}
+
+			// printGame()
+			fmt.Printf("#%d: %-15q %-20s $%d\n",
+				g.id, g.name, "("+g.genre+")", g.price)
+		}
+	}
+}

25-functions/exercises/refactor-to-funcs-1/solution/games.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"
+
+type item struct {
+	id    int
+	name  string
+	price int
+}
+
+type game struct {
+	item
+	genre string
+}
+
+func load() (games []game) {
+	games = addGame(games, newGame(1, 50, "god of war", "action adventure"))
+	games = addGame(games, newGame(2, 40, "x-com 2", "strategy"))
+	games = addGame(games, newGame(3, 20, "minecraft", "sandbox"))
+	return
+}
+
+func addGame(games []game, g game) []game {
+	return append(games, g)
+}
+
+func newGame(id, price int, name, genre string) game {
+	return game{
+		item:  item{id: id, name: name, price: price},
+		genre: genre,
+	}
+}
+
+func indexByID(games []game) (byID map[int]game) {
+	byID = make(map[int]game)
+	for _, g := range games {
+		byID[g.id] = g
+	}
+	return
+}
+
+func printGame(g game) {
+	fmt.Printf("#%d: %-15q %-20s $%d\n",
+		g.id, g.name, "("+g.genre+")", g.price)
+}

25-functions/exercises/refactor-to-funcs-1/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 (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	games := load()
+	byID := indexByID(games)
+
+	fmt.Printf("Inanc's game store has %d games.\n", len(games))
+
+	in := bufio.NewScanner(os.Stdin)
+	for {
+		fmt.Printf(`
+  > list   : lists all the games
+  > id N   : queries a game by id
+  > quit   : quits
+
+`)
+
+		if !in.Scan() {
+			break
+		}
+
+		fmt.Println()
+
+		cmd := strings.Fields(in.Text())
+		if len(cmd) == 0 {
+			continue
+		}
+
+		switch cmd[0] {
+		case "quit":
+			fmt.Println("bye!")
+			return
+
+		case "list":
+			for _, g := range games {
+				printGame(g)
+			}
+
+		case "id":
+			if len(cmd) != 2 {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			id, err := strconv.Atoi(cmd[1])
+			if err != nil {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			g, ok := byID[id]
+			if !ok {
+				fmt.Println("sorry. i don't have the game")
+				continue
+			}
+
+			printGame(g)
+		}
+	}
+}

25-functions/exercises/refactor-to-funcs-2/games.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"
+
+type item struct {
+	id    int
+	name  string
+	price int
+}
+
+type game struct {
+	item
+	genre string
+}
+
+func load() (games []game) {
+	games = addGame(games, newGame(1, 50, "god of war", "action adventure"))
+	games = addGame(games, newGame(2, 40, "x-com 2", "strategy"))
+	games = addGame(games, newGame(3, 20, "minecraft", "sandbox"))
+	return
+}
+
+func addGame(games []game, g game) []game {
+	return append(games, g)
+}
+
+func newGame(id, price int, name, genre string) game {
+	return game{
+		item:  item{id: id, name: name, price: price},
+		genre: genre,
+	}
+}
+
+func indexByID(games []game) (byID map[int]game) {
+	byID = make(map[int]game)
+	for _, g := range games {
+		byID[g.id] = g
+	}
+	return
+}
+
+func printGame(g game) {
+	fmt.Printf("#%d: %-15q %-20s $%d\n",
+		g.id, g.name, "("+g.genre+")", g.price)
+}

25-functions/exercises/refactor-to-funcs-2/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/
+//
+
+// ---------------------------------------------------------
+// EXERCISE: Refactor the game store to funcs - step #2
+//
+//  Let's continue the refactoring from the previous
+//  exercise. This time, you're going to refactor the
+//  command handling logic.
+//
+//
+//  Create commands.go file
+//
+//     1- Add a func that runs the given command from the user:
+//
+//        Name  : runCmd
+//        Inputs: input string, []game, map[int]game
+//        Output: bool
+//
+//        This func returns true if it wants the program to
+//        continue. When it returns false, the program will
+//        terminate. So, all the commands that it calls need
+//        to return true or false as well depending on whether
+//        they want to cause the program to terminate or not.
+//
+//     2- Add a func that handles the quit command:
+//
+//        Name  : cmdQuit
+//        Input : none
+//        Output: bool
+//
+//     3- Add a func that handles the list command:
+//
+//        Name  : cmdList
+//        Inputs: []game
+//        Output: bool
+//
+//     4- Add a func that handles the id command:
+//
+//        Name  : cmdByID
+//        Inputs: cmd []string, []game, map[int]game
+//        Output: bool
+//
+//     5- Refactor the runCmd() with the cmdXXX funcs.
+//
+//  Go back to main.go and change the existing code with
+//  the new funcs that you've created. There are hints
+//  inside the code.
+//
+// ---------------------------------------------------------
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	games := load()
+	byID := indexByID(games)
+
+	fmt.Printf("Inanc's game store has %d games.\n", len(games))
+
+	in := bufio.NewScanner(os.Stdin)
+	for {
+		// menu()
+		fmt.Printf(`
+  > list   : lists all the games
+  > id N   : queries a game by id
+  > quit   : quits
+
+`)
+
+		if !in.Scan() {
+			break
+		}
+
+		// --- runCmd start ---
+		fmt.Println()
+
+		cmd := strings.Fields(in.Text())
+		if len(cmd) == 0 {
+			continue
+		}
+
+		switch cmd[0] {
+		case "quit":
+			// cmdQuit()
+			fmt.Println("bye!")
+			return
+
+		case "list":
+			// cmdList()
+			for _, g := range games {
+				printGame(g)
+			}
+
+		case "id":
+			// cmdByID
+			if len(cmd) != 2 {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			id, err := strconv.Atoi(cmd[1])
+			if err != nil {
+				fmt.Println("wrong id")
+				continue
+			}
+
+			g, ok := byID[id]
+			if !ok {
+				fmt.Println("sorry. i don't have the game")
+				continue
+			}
+
+			printGame(g)
+		}
+		// --- runCmd end ---
+	}
+}

25-functions/exercises/refactor-to-funcs-2/solution/commands.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"
+	"strconv"
+	"strings"
+)
+
+func runCmd(input string, games []game, byID map[int]game) bool {
+	fmt.Println()
+
+	cmd := strings.Fields(input)
+	if len(cmd) == 0 {
+		return true
+	}
+
+	switch cmd[0] {
+	case "quit":
+		return cmdQuit()
+
+	case "list":
+		return cmdList(games)
+
+	case "id":
+		return cmdByID(cmd, games, byID)
+	}
+	return true
+}
+
+func cmdQuit() bool {
+	fmt.Println("bye!")
+	return false
+}
+
+func cmdList(games []game) bool {
+	for _, g := range games {
+		printGame(g)
+	}
+	return true
+}
+
+func cmdByID(cmd []string, games []game, byID map[int]game) bool {
+	if len(cmd) != 2 {
+		fmt.Println("wrong id")
+		return true
+	}
+
+	id, err := strconv.Atoi(cmd[1])
+	if err != nil {
+		fmt.Println("wrong id")
+		return true
+	}
+
+	g, ok := byID[id]
+	if !ok {
+		fmt.Println("sorry. i don't have the game")
+		return true
+	}
+
+	printGame(g)
+
+	return true
+}

25-functions/exercises/refactor-to-funcs-2/solution/games.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"
+
+type item struct {
+	id    int
+	name  string
+	price int
+}
+
+type game struct {
+	item
+	genre string
+}
+
+func load() (games []game) {
+	games = addGame(games, newGame(1, 50, "god of war", "action adventure"))
+	games = addGame(games, newGame(2, 40, "x-com 2", "strategy"))
+	games = addGame(games, newGame(3, 20, "minecraft", "sandbox"))
+	return
+}
+
+func addGame(games []game, g game) []game {
+	return append(games, g)
+}
+
+func newGame(id, price int, name, genre string) game {
+	return game{
+		item:  item{id: id, name: name, price: price},
+		genre: genre,
+	}
+}
+
+func indexByID(games []game) (byID map[int]game) {
+	byID = make(map[int]game)
+	for _, g := range games {
+		byID[g.id] = g
+	}
+	return
+}
+
+func printGame(g game) {
+	fmt.Printf("#%d: %-15q %-20s $%d\n",
+		g.id, g.name, "("+g.genre+")", g.price)
+}

25-functions/exercises/refactor-to-funcs-2/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 (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	games := load()
+	byID := indexByID(games)
+
+	fmt.Printf("Inanc's game store has %d games.\n", len(games))
+
+	in := bufio.NewScanner(os.Stdin)
+	for {
+		fmt.Printf(`
+  > list   : lists all the games
+  > id N   : queries a game by id
+  > quit   : quits
+
+`)
+
+		if !in.Scan() || !runCmd(in.Text(), games, byID) {
+			break
+		}
+	}
+}

25-functions/questions/README.md

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+## ?
+1. text *CORRECT*
+2. text
+
+> **1:**
+>
+