用tkinter写一个简易计算器，只包含加、减、乘、除四种运算。

好的，下面是一个简单的计算器示例代码：

import tkinter as tk

# 创建主窗口
root = tk.Tk()
root.title("简易计算器")

# 创建显示框
display = tk.Entry(root, width=30, justify="right")
display.grid(row=0, column=0, columnspan=4, padx=5, pady=5)

# 定义按钮点击事件
def button_click(value):
    current = display.get()
    display.delete(0, tk.END)
    display.insert(0, str(current) + str(value))

def button_clear():
    display.delete(0, tk.END)

def button_add():
    first_number = display.get()
    global f_num
    global math
    math = "addition"
    f_num = int(first_number)
    display.delete(0, tk.END)

def button_subtract():
    first_number = display.get()
    global f_num
    global math
    math = "subtraction"
    f_num = int(first_number)
    display.delete(0, tk.END)

def button_multiply():
    first_number = display.get()
    global f_num
    global math
    math = "multiplication"
    f_num = int(first_number)
    display.delete(0, tk.END)

def button_divide():
    first_number = display.get()
    global f_num
    global math
    math = "division"
    f_num = int(first_number)
    display.delete(0, tk.END)

def button_equal():
    second_number = display.get()
    display.delete(0, tk.END)

    if math == "addition":
        display.insert(0, f_num + int(second_number))
    elif math == "subtraction":
        display.insert(0, f_num - int(second_number))
    elif math == "multiplication":
        display.insert(0, f_num * int(second_number))
    elif math == "division":
        display.insert(0, f_num / int(second_number))

# 创建按钮
button_1 = tk.Button(root, text="1", padx=30, pady=20, command=lambda: button_click(1))
button_2 = tk.Button(root, text="2", padx=30, pady=20, command=lambda: button_click(2))
button_3 = tk.Button(root, text="3", padx=30, pady=20, command=lambda: button_click(3))
button_4 = tk.Button(root, text="4", padx=30, pady=20, command=lambda: button_click(4))
button_5 = tk.Button(root, text="5", padx=30, pady=20, command=lambda: button_click(5))
button_6 = tk.Button(root, text="6", padx=30, pady=20, command=lambda: button_click(6))
button_7 = tk.Button(root, text="7", padx=30, pady=20, command=lambda: button_click(7))
button_8 = tk.Button(root, text="8", padx=30, pady=20, command=lambda: button_click(8))
button_9 = tk.Button(root, text="9", padx=30, pady=20, command=lambda: button_click(9))
button_0 = tk.Button(root, text="0", padx=30, pady=20, command=lambda: button_click(0))
button_add = tk.Button(root, text="+", padx=30, pady=20, command=button_add)
button_subtract = tk.Button(root, text="-", padx=30, pady=20, command=button_subtract)
button_multiply = tk.Button(root, text="*", padx=30, pady=20, command=button_multiply)
button_divide = tk.Button(root, text="/", padx=30, pady=20, command=button_divide)
button_clear = tk.Button(root, text="C", padx=30, pady=20, command=button_clear)
button_equal = tk.Button(root, text="=", padx=30, pady=20, command=button_equal)

# 将按钮添加到主窗口
button_1.grid(row=3, column=0)
button_2.grid(row=3, column=1)
button_3.grid(row=3, column=2)
button_add.grid(row=3, column=3)

button_4.grid(row=2, column=0)
button_5.grid(row=2, column=1)
button_6.grid(row=2, column=2)
button_subtract.grid(row=2, column=3)

button_7.grid(row=1, column=0)
button_8.grid(row=1, column=1)
button_9.grid(row=1, column=2)
button_multiply.grid(row=1, column=3)

button_clear.grid(row=4, column=0)
button_0.grid(row=4, column=1)
button_equal.grid(row=4, column=2)
button_divide.grid(row=4, column=3)

# 进入消息循环
root.mainloop()

这个计算器界面比较简单，只有一个显示框和16个按钮。代码中，我们使用了lambda表达式来将按钮的点击事件与对应的数字绑定起来，使用全局变量来记录当前的运算符和第一个数字，使用if-else语句来判断运算符并进行相应的计算，最后将结果显示在显示框中。