在Python 3中使用tkinter時，如何在每次按下函數時獲得一個按鈕來運行函數？

Question

import tkinter as tk
panel = tk.Tk()
num = 42
lbl1 = tk.Label(panel, text = str(num))

假設我有一個像這樣的功能和按鈕：

def increase():
    lbl1.configure(text = str(num+1))

btn = tk.Button(panel, text = 'Increase', command = increase)

panel.mainloop()

按下按鈕時，標簽上的數字將增加1。 但是，此操作僅在按鈕完全不起作用之前起作用一次。 如何使每次按下按鈕時數字增加1？

Answer 1

您從未保存過num的增量值。

def increase():
    global num # declare it a global so we can modify it
    num += 1 # modify it
    lbl1.configure(text = str(num)) # use it

Answer 2

因為num總是43

import tkinter as tk
num = 42

def increase():
    global num
    num += 1
    lbl1.configure(text = str(num))


panel = tk.Tk()

lbl1 = tk.Label(panel, text = str(num))
lbl1.pack()
btn = tk.Button(panel, text = 'Increase', command = increase)
btn.pack()
panel.mainloop()