Added solution (#32)

Author: DennisVis

students/dennisvis/main.go

@@ -0,0 +1,155 @@
+package main
+
+import (
+	"bufio"
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"math/rand"
+	"os"
+	"strings"
+	"time"
+)
+
+type problem struct {
+	question string
+	answer   string
+}
+
+var (
+	problemsFile = flag.String("problems", "problems.csv", "A CSV file containing problems and their solutions")
+	quizTime     = flag.Int("time", 30, "The time in seconds this quiz will run")
+	shuffle      = flag.Bool("shuffle", false, "Wheteher or not to shuffle the problems")
+	osR          = bufio.NewReader(os.Stdin)
+)
+
+func readProblems(csvFile *os.File) []problem {
+	csvR := csv.NewReader(csvFile)
+
+	problems := make([]problem, 0)
+	for {
+		record, err := csvR.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			log.Fatal(err)
+		}
+		if record[0] != "" && record[1] != "" {
+			problems = append(problems, problem{record[0], strings.ToLower(record[1]})
+		}
+	}
+
+	return problems
+}
+
+func shuffleProblems(problems []problem) {
+	r := rand.New(rand.NewSource(time.Now().Unix()))
+	for i1 := 0; i1 < len(problems); i1++ {
+		i2 := r.Intn(len(problems))
+
+		problem1 := problems[i1]
+		problem2 := problems[i2]
+
+		problems[i1] = problem2
+		problems[i2] = problem1
+	}
+}
+
+func askQuestion(q string, tries int8) string {
+	fmt.Printf("\n%s: ", q)
+	input, err := osR.ReadString('\n')
+	if err != nil {
+		if tries < 5 {
+			log.Println("Your answer could not be processed, please try again")
+			return askQuestion(q, tries+1)
+		}
+		log.Fatal("Something is wrong with this program, going to exit...")
+	}
+	return strings.ToLower(strings.TrimSpace(strings.TrimRight(input, "\n")))
+}
+
+func askQuestions(problems []problem, timer, correctAnswersChan, done chan interface{}) {
+	index := 0
+	for {
+		select {
+		case <-timer:
+			fmt.Println("\nTime's up!")
+			return
+
+		default:
+			if index >= len(problems) {
+				close(done)
+				return
+			}
+
+			problem := problems[index]
+			answer := askQuestion(problem.question, 0)
+			if answer == problem.answer {
+				correctAnswersChan <- true
+				fmt.Println("Correct!")
+			} else {
+				fmt.Println("False...")
+			}
+			index = index + 1
+		}
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	if !strings.HasSuffix(*problemsFile, "csv") {
+		log.Fatalf("Provided problems file '%s' is not a CSV file", *problemsFile)
+	}
+
+	csvFile, err := os.Open(*problemsFile)
+	if err != nil {
+		log.Fatalf("Could not open '%s'", *problemsFile)
+	}
+
+	problems := readProblems(csvFile)
+	totalProblems := len(problems)
+	if *shuffle {
+		shuffleProblems(problems)
+	}
+
+	timer := make(chan interface{})
+	correctAnswersChan := make(chan interface{})
+	done := make(chan interface{})
+
+	fmt.Println("Press ENTER to start the quiz...")
+	osR.ReadString('\n')
+
+	correctAnswers := 0
+	go func() {
+		for {
+			select {
+			case _ = <-correctAnswersChan:
+				correctAnswers = correctAnswers + 1
+			case <-done:
+				return
+			}
+		}
+	}()
+
+	go askQuestions(problems, timer, correctAnswersChan, done)
+
+	time.Sleep(time.Duration(*quizTime) * time.Second)
+	close(timer)
+	close(done)
+
+	if totalProblems == correctAnswers {
+		fmt.Println("\nCongratulations! You answered all questions correctly!")
+	} else {
+		fmt.Printf(
+			"\nYou answered %d questions correctly but failed to do so for %d questions, try again",
+			correctAnswers,
+			totalProblems-correctAnswers,
+		)
+	}
+
+	os.Exit(0)
+}

students/dennisvis/problems.csv

@@ -0,0 +1,12 @@
+5+5,10
+1+1,2
+8+3,11
+1+2,3
+8+6,14
+3+1,4
+1+4,5
+5+1,6
+2+3,5
+3+3,6
+2+4,6
+5+2,7