运用GUI模拟ATM自动提款机，写出代码

以下是一个简单的 GUI 模拟 ATM 自动提款机的 Python 代码：

from tkinter import *
from tkinter import messagebox

class ATM:
    def __init__(self, master):
        self.master = master
        master.title("ATM")

        # 创建标签、输入框、按钮
        self.balance_label = Label(master, text="余额：")
        self.balance_label.grid(row=0, column=0)

        self.balance_entry = Entry(master)
        self.balance_entry.grid(row=0, column=1)

        self.withdraw_label = Label(master, text="取款金额：")
        self.withdraw_label.grid(row=1, column=0)

        self.withdraw_entry = Entry(master)
        self.withdraw_entry.grid(row=1, column=1)

        self.withdraw_button = Button(master, text="取款", command=self.withdraw)
        self.withdraw_button.grid(row=2, column=1)

    def withdraw(self):
        # 获取余额和取款金额
        balance = float(self.balance_entry.get())
        withdraw_amount = float(self.withdraw_entry.get())

        # 判断余额是否充足
        if balance >= withdraw_amount:
            balance -= withdraw_amount
            self.balance_entry.delete(0, END)
            self.balance_entry.insert(0, str(balance))
            messagebox.showinfo("成功", "取款成功！")
        else:
            messagebox.showerror("错误", "余额不足！")

# 创建主窗口
root = Tk()

# 创建 ATM 对象
atm = ATM(root)

# 进入事件循环
root.mainloop()

这个 GUI 程序包含一个余额标签、一个余额输入框、一个取款金额标签、一个取款金额输入框和一个取款按钮。当用户点击取款按钮时，程序会检查余额是否充足，如果充足则从余额中扣除取款金额，并更新余额输入框的显示。如果余额不足，则弹出错误消息框。