[Go] guess number demo.

package main

import (
    "bufio"
    "fmt"
    "math/rand"
    "os"
    "strconv"
    "time"
)

func main() {
    const MIN int = 1
    const MAX int = 100

    // Init a new rand object
    r := rand.New(rand.NewSource(time.Now().UnixNano()))

    // Init the state of our program
    answer := r.Intn(MAX) + MIN
    guess := -1
    min := MIN
    max := MAX

    // Build a scanner object which receives data from standard input
    scanner := bufio.NewScanner(os.Stdin)

    // Main game loop
OUTER_LOOP:
    for {
        // Receive user input
    INNER_LOOP:
        for {
            fmt.Print("Input a number between ", min, " and ", max, ": ")

            for scanner.Scan() {
                input := scanner.Text()

                n, err := strconv.ParseInt(input, 10, 0) // n is int64

                // Convert the number from int64 to int
                num := int(n)

                if err != nil {
                    fmt.Fprintf(os.Stderr, "Invalid number: %s\n", input)
                    break
                } else if num < min || num > max {
                    fmt.Fprintf(os.Stderr, "Number out of range: %d\n", num)
                    break
                } else {
                    guess = num
                    break INNER_LOOP
                }
            }
        }

        // Check our guess is correct
        if guess > answer {
            fmt.Println("Too large")
            max = guess
        } else if guess < answer {
            fmt.Println("Too small")
            min = guess
        } else {
            fmt.Println("You guess right")
            break OUTER_LOOP
        }
    }
}