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本课属于 Coddy Ruby 学习旅程的“基础知识”单元。第 81 课，共 88 课。

挑战

简单

在上一课的费用追踪器基础上，添加“Add Expense”功能。

你的程序应该：

初始化一个名为 expenses 的空数组
创建一个 loop do，用于显示菜单并读取用户输入
当用户输入 "1" 时，提示输入费用名称和金额，创建一个包含 :name 和 :amount 键的哈希，将它添加到 expenses 数组中，并输出 Expense added!
当用户输入 "5" 时，输出 Goodbye! 并退出循环

菜单应与之前完全一致：


--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option:

选择选项 "1" 时，显示以下提示：

Expense name:

读取名称后：

Amount:

所有提示都使用 print（这样光标会停留在同一行）。使用 to_f 将金额转换为浮点数。

程序会依次收到多个输入：菜单选项；如果选项是 "1"，接下来会输入费用名称和金额。

例如，如果输入依次为 1、Coffee、4.50，然后是 5，输出应为：


--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option: Expense name: Amount: Expense added!

--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option: Goodbye!

如果输入依次为 1、Lunch、12.99、1、Bus fare、2.50，然后是 5，输出应为：


--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option: Expense name: Amount: Expense added!

--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option: Expense name: Amount: Expense added!

--- Expense Tracker ---
1. Add Expense
2. View Expenses
3. Total & Average
4. Clear All
5. Exit
Choose an option: Goodbye!

亲手试试

expenses = []

loop do
  puts "\n--- Expense Tracker ---"
  puts "1. Add Expense"
  puts "2. View Expenses"
  puts "3. Total & Average"
  puts "4. Clear All"
  puts "5. Exit"
  print "Choose an option: "
  
  choice = gets.chomp
  
  if choice == "5"
    puts "Goodbye!"
    break
  end
end