to create a button when pressed print the number on that button in the entry box in python 3.3

Question

i want to make a button on which \'2\' is written .... now when anyone click it , it will show the number \'2\' in the entry box... the error is: before clicking , it is a

Answer 1

Pass a function (used lambda in the following code) instead of return value of the function.

from tkinter import * 

root = Tk()  
e1 = Entry(root)  
e1.pack()

def add(x):  
    e1.insert(INSERT, x)  

a = Button(root, text='2', command=lambda: add(2))
a.pack()

root.mainloop()

In addition to that, extract Entry creation code out of the add function. Otherwise entry are create every time when the button is clicked.

Answer 2

When you do:

a=Button(root, text='2', command=add(2))  

it is the same as:

add(2)
a=Button(root, text='2', command=None)  

i.e. you are calling add and assigning its return value to command. Instead, you can use functools.partial to create a function that will call add with the argument 2:

from functools import partial

a=Button(root, text='2', command=partial(add, 2))