Exercise #6 from "Get Programming with Go" book by by Nathan Youngman and Roger Peppé

piggy.go

/*
Write a program that randomly places nickels ($0.05), dimes ($0.10),
and quarters ($0.25) into an empty piggy bank until it contains at least $20.00.
Display the running balance of the piggy bank after each deposit,
formatting it with an appropriate width and precision.
*/

package main

import (
	"fmt"
	"math/rand"
	"time"
)

const (
	bankThreshold = 20.0
)

var coinsValue = [...]float64{0.05, 0.1, 0.25}

// coin generates random coin from coinsValues
func coin() float64 {
	return coinsValue[rand.Intn(len(coinsValue))]
}

func main() {
	// set random numbers, otherwise it will produce the same results
	rand.Seed(time.Now().UnixNano())
	piggyBank := 0.0
	for piggyBank <= bankThreshold {
		coin := coin()
		piggyBank += coin
		fmt.Printf("Coin: %5.2f: Bank %5.2f\n", coin, piggyBank)
	}
	fmt.Printf("%4.2f or %v\n", piggyBank, piggyBank)
}