查看所有开支

本课属于 Coddy Swift 学习旅程的“基础知识”单元。第 80 课，共 86 课。

挑战

简单

在上一课中，你实现了“Add expense”功能。现在，为选项 "2" 实现“View all expenses”功能。

修改代码以处理选项 "2"：

当用户输入 "2" 时，检查 expenses 数组是否为空
如果数组为空，打印 No expenses recorded.
如果数组中有支出，打印 Your expenses:，然后将每笔支出各占一行打印出来，格式为 - $ 后跟金额，金额格式与 Swift 打印 Double 的格式相同（例如，25.50 会打印为 - $25.5）
选项 "3" 和 "4" 仍应打印 Coming soon...
选项 "1" 和 "5" 应继续像以前一样工作

预期行为：

没有支出时输入 "2"，打印 No expenses recorded.
有支出时输入 "2"，打印标题，并用短横线和美元符号列出每笔支出

交互示例：

1. Add expense
2. View all expenses
3. Show total and average
4. Clear all expenses
5. Exit
2
No expenses recorded.
1. Add expense
2. View all expenses
3. Show total and average
4. Clear all expenses
5. Exit
1
Enter expense amount:
25.50
Expense added!
1. Add expense
2. View all expenses
3. Show total and average
4. Clear all expenses
5. Exit
1
Enter expense amount:
10.00
Expense added!
1. Add expense
2. View all expenses
3. Show total and average
4. Clear all expenses
5. Exit
2
Your expenses:
- $25.5
- $10.0
1. Add expense
2. View all expenses
3. Show total and average
4. Clear all expenses
5. Exit
5
Goodbye!

亲手试试

// Daily Expense Tracker - Menu Display

var expenses: [Double] = []

while true {
    // TODO: Write your code below to print the menu options
    // Each option should be on its own line with the format: "number. option text"
    print("1. Add expense")
    print("2. View all expenses")
    print("3. Show total and average")
    print("4. Clear all expenses")
    print("5. Exit")
    
    let choice = readLine()
    
    if choice == "1" {
        print("Enter expense amount:")
        if let input = readLine(), let amount = Double(input) {
            expenses.append(amount)
            print("Expense added!")
        }
    } else if choice == "2" {
        print("Coming soon...")
    } else if choice == "3" {
        print("Coming soon...")
    } else if choice == "4" {
        print("Coming soon...")
    } else if choice == "5" {
        print("Goodbye!")
        break
    } else {
        print("Coming soon...")
    }
}

基础知识中的所有课

自己练习： Swift 在线编辑器