Golang : Find change in a combination of coins example

If you are planning to build a vending machine, self-service cashier machine or any machines that deal with money. Chances are the machine will need to have the ability to find out how much change in coins needed to be given back to the customers. Before deciding how much change needs to be given back, first the program needs to breakdown or know the combination of coins of a given value.

For example, given a 50% value of a dollar, what is the combination of coins that will make up the 50% value of a dollar? Mathematically, it should be 2 quarters.

The code that follows is an example program that will take in an integer value from 1 to 100 and prints out the change combination.

Here you go!

---

 package main

 import (
 "fmt"
 "os"
 )

 var (
 amount, originalAmount, quarters, dimes, nickels, pennies int
 )

 func sanityCheck(input, min, max int) {

 if !((input >= min) && (input <= max)) {
 fmt.Printf("Input parameter must in between %d and %d.\n", min, max)
 os.Exit(-1)
 }

 }

 func main() {
 fmt.Println("Enter an integer value from 1 to 100 : ")
 fmt.Println("and I will show you a combination of coins")
 fmt.Println("that equals to the number.")

 _, err := fmt.Scanf("%d", &amount)

 if err != nil {
 fmt.Println(err)
 }

 sanityCheck(amount, 1, 100)

 fmt.Println("You have entered : ", amount)

 originalAmount = amount
 quarters = amount / 25
 amount = amount % 25
 dimes = amount / 10
 amount = amount % 10
 nickels = amount / 5
 amount = amount % 5
 pennies = amount

 fmt.Println("Original amount entered : ", originalAmount)
 fmt.Println("Has a combination in coins of : ")
 fmt.Println("Quarters : ", quarters)
 fmt.Println("Dimes : ", dimes)
 fmt.Println("Nickels : ", nickels)
 fmt.Println("Pennies : ", pennies)

 }

---

Sample output:

Enter an integer value from 1 to 100 :

and I will show you a combination of coins

that equals to the number.

You have entered : 100

Original amount entered : 100

Has a combination in coins of :

Quarters : 4

Dimes : 0

Nickels : 0

Pennies : 0

---

Enter an integer value from 1 to 100 :

and I will show you a combination of coins

that equals to the number.

2

You have entered : 2

Original amount entered : 2

Has a combination in coins of :

Quarters : 0

Dimes : 0

Nickels : 0

Pennies : 2

---

Enter an integer value from 1 to 100 :

and I will show you a combination of coins

that equals to the number.

88

You have entered : 88

Original amount entered : 88

Has a combination in coins of :

Quarters : 3

Dimes : 1

Nickels : 0

Pennies : 3

References:

https://socketloop.com/tutorials/golang-integer-is-between-a-range

https://www.socketloop.com/tutorials/golang-how-to-read-integer-value-from-standard-input

https://www.socketloop.com/tutorials/golang-how-to-check-if-input-from-os-args-is-integer