from tkinter import *

def conversion():
    n = int(x.get())
    nb = int(y.get())
    if not (-2 ** (nb-1) <= n < 2 ** (nb-1)):
        lab3.configure(text ="nombre de bits insuffisant")
        nombre.set("")
        nombre2.set("")
        return 
    if n < 0:
        n = n + 2 ** nb
    res = ""
    cpt = 0
    while n > 0:
        cpt += 1
        r = n % 2
        res = str(r) + res
        n = n // 2
    lab3.configure(text = "Le nombre "+x.get()+" s'écrit sur "+y.get()+" bits: "+(nb-cpt)*'0'+res)
    nombre.set("")
    nombre2.set("")

fenetre = Tk()
fenetre.title("Convertir un nombre entier relatif")

fenetre.geometry("400x100")

lab1 = Label(fenetre, text = 'Ecrire un nombre entier relatif: ')
lab1.grid(row = 0, column = 0)

nombre = StringVar()
x = Entry(fenetre, width = 10, textvariable = nombre)
x.grid(row = 0, column = 1)

lab2 = Label(fenetre, text = 'Choisir le nombre de bits: ')
lab2.grid(row = 1, column = 0)

nombre2 = StringVar()
y = Entry(fenetre, width = 10, textvariable = nombre2)
y.grid(row = 1, column = 1)

b1 = Button(fenetre, text = "OK", command = conversion)
b1.grid(row = 1, column = 2)

lab3 = Label(fenetre, text = "")
lab3.grid(row = 2, column = 0)

b2=Button(fenetre, text = "Quitter", command = fenetre.destroy)
b2.grid(row = 3,column = 2)

fenetre.mainloop()