Challenge 2 — Solution

Task: Define a struct Account with field Balance (float64). Write a
method (a *Account) Deposit(amount float64) using a pointer receiver
that adds amount to Balance. Create an account, call Deposit twice
with different amounts, and print Balance after each call to
confirm it actually changes.

package main

import "fmt"

type Account struct {
	Balance float64
}

func (a *Account) Deposit(amount float64) {
	a.Balance += amount
}

func main() {
	account := Account{Balance: 100}

	account.Deposit(50)
	fmt.Println(account.Balance)

	account.Deposit(25.50)
	fmt.Println(account.Balance)
}


Expected output:

150
175.5

Notes:
- Deposit MUST use a pointer receiver (*Account) — with a plain
  Account receiver, a.Balance += amount would only change a
  temporary copy, and account.Balance would still read 100 after
  both calls.
- account.Deposit(50) works even though account itself is a plain
  Account, not a pointer — Go automatically takes its address behind
  the scenes when calling a pointer-receiver method this way.
- Each call permanently updates the same underlying account, which
  is exactly why the second print shows 175.5, building on the first
  deposit rather than starting over from 100.