Tkinter calculator how to clear past answer when start a new calculation

user_12011419 0
Viewed 352

I have a simple calculator code but when i want to start a new calculation after pressing equal the answer from last calculation wont get clear unless i press the clear button (it starts behind the answer), so now i want to make it clear past answer when i start new calculation. Thanks in advance!

from tkinter import *

root = Tk()
root.title("Simple Calculator")
e = Entry(root, width=35, borderwidth=5)
e.grid(row=0, column=0, columnspan=3, padx=10, pady=1)

perhaps i need some kind of boolean here

def button_click(number):
    current = e.get()
    e.delete(0, END)
    e.insert(0, str(current) + str(number))

def button_clear():
    e.delete(0, END)


def button_add():
    first_number = e.get()
    global f_num
    f_num = int(first_number)
    e.delete(0, END)


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

    if math == "addition":
        e.delete(0, END)
        e.insert(0, f_num + int(second_number))

    if math == "subtraction":
        e.delete(0, END)
        e.insert(0, f_num - int(second_number))

    if math == "multiplication":
        e.delete(0, END)
        e.insert(0, f_num * int(second_number))

    if math == "division":
        e.delete(0, END)
        e.insert(0, f_num / int(second_number))


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


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


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


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


button_1 = Button(root, text="1", padx=40, pady=20, bg="white", command=lambda: button_click(1))
button_2 = Button(root, text="2", padx=40, pady=20, bg="white", command=lambda: button_click(2))
button_3 = Button(root, text="3", padx=40, pady=20, bg="white", command=lambda: button_click(3))
button_4 = Button(root, text="4", padx=40, pady=20, bg="white", command=lambda: button_click(4))
button_5 = Button(root, text="5", padx=40, pady=20, bg="white", command=lambda: button_click(5))
button_6 = Button(root, text="6", padx=40, pady=20, bg="white", command=lambda: button_click(6))
button_7 = Button(root, text="7", padx=40, pady=20, bg="white", command=lambda: button_click(7))
button_8 = Button(root, text="8", padx=40, pady=20, bg="white", command=lambda: button_click(8))
button_9 = Button(root, text="9", padx=40, pady=20, bg="white", command=lambda: button_click(9))
button_0 = Button(root, text="0", padx=40, pady=20, bg="white", command=lambda: button_click(0))

button_equal = Button(root, text="=", padx=90, pady=20, bg="white", command=button_equal)
button_clear = Button(root, text="clear", padx=80, pady=20, bg="white", command=button_clear)
button_add = Button(root, text="+", padx=40, pady=20, bg="white", command=button_add)
button_subtract = Button(root, text="-", padx=40, pady=20, bg="white", command=button_subtract)
button_multiply = Button(root, text="*", padx=40, pady=20, bg="white", command=button_multiply)
button_divide = Button(root, text="/", padx=40, pady=20, bg="white", command=button_divide)


button_1.grid(row=3, column=0)
button_2.grid(row=3, column=1)
button_3.grid(row=3, column=2)

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

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

button_0.grid(row=4, column=0)
button_clear.grid(row=4, column=1, columnspan=2)
button_add.grid(row=5, column=0)
button_equal.grid(row=5, column=1, columnspan=2)

button_subtract.grid(row=6, column=0)
button_multiply.grid(row=6, column=1)
button_divide.grid(row=6, column=2)

root.mainloop()
tkinter python
1 Answers

One way of doing it is by giving a signal. For example, set equals=False in the beginning, it should become True only if the user presses = button. You must keep checking if the equals become True in the button_click function, if it is True and the next inserted element is a digit then delete all the text in the text box.

Here is a demonstration. You may further improve this if you wish to.

from tkinter import *
import re

def _split(number):

    global lst
    global operation
    
    lst = re.split(r'[^\w]', number)
    lst = [x for x in lst if x!='']

    if len(lst)==1:
        return None, None
    
    lst = list(map(int, lst))

    operation = re.split(r'[\d]', number)
    
    operation = [x for x in operation if x != '']
    

    return lst, operation

def operate(numbers, operation):
    
    if operation == '+':
        return numbers[0] + numbers[1]

    elif operation == '-':
        return numbers[0] - numbers[1]

    elif operation == '*':
        return numbers[0] * numbers[1]

    elif operation == '/':
        try:
            return numbers[0]/numbers[1]

        except:
            print('ERROR')
            
    else:
        print('Invalid operation')

    
def button_click(number):
  
    global equals

    operand = []
    
    e.insert(END, str(number))
    
    if e.get()[-1:].isdigit() and equals:
        e.delete(0, END)
        e.insert(END, str(number))
    
    equals = False

    operand, operation = _split(e.get())

    if operation != None and len(operation)==2:
        value = operate(operand, operation[0])
        e.delete(0, END)
        e.insert(0, f'{value}{operation[1]}')
    
def button_clear():
    e.delete(0, END)


def button_equal():
    global equals
    number = e.get()
    operand, operation = _split(number)

    value = number
    
    if operand and operation:
        value = operate(operand, operation[0])
        equals = True 
    
    
    e.delete(0, END)
    e.insert(0, value)


root = Tk()
root.title("Simple Calculator")

e = Entry(root, width=35, borderwidth=5)
e.grid(row=0, column=0, columnspan=3, padx=10, pady=1)

equals = False
operation = None
lst = [0]

button_1 = Button(root, text="1", padx=40, pady=20, bg="white", command=lambda: button_click(1))
button_2 = Button(root, text="2", padx=40, pady=20, bg="white", command=lambda: button_click(2))
button_3 = Button(root, text="3", padx=40, pady=20, bg="white", command=lambda: button_click(3))
button_4 = Button(root, text="4", padx=40, pady=20, bg="white", command=lambda: button_click(4))
button_5 = Button(root, text="5", padx=40, pady=20, bg="white", command=lambda: button_click(5))
button_6 = Button(root, text="6", padx=40, pady=20, bg="white", command=lambda: button_click(6))
button_7 = Button(root, text="7", padx=40, pady=20, bg="white", command=lambda: button_click(7))
button_8 = Button(root, text="8", padx=40, pady=20, bg="white", command=lambda: button_click(8))
button_9 = Button(root, text="9", padx=40, pady=20, bg="white", command=lambda: button_click(9))
button_0 = Button(root, text="0", padx=40, pady=20, bg="white", command=lambda: button_click(0))

button_equal = Button(root, text="=", padx=90, pady=20, bg="white", command=button_equal)
button_clear = Button(root, text="clear", padx=80, pady=20, bg="white", command=button_clear)
button_add = Button(root, text="+", padx=40, pady=20, bg="white", command=lambda :button_click('+'))
button_subtract = Button(root, text="-", padx=40, pady=20, bg="white", command=lambda :button_click('-'))
button_multiply = Button(root, text="*", padx=40, pady=20, bg="white", command=lambda :button_click('*'))
button_divide = Button(root, text="/", padx=40, pady=20, bg="white", command=lambda :button_click('/'))


button_1.grid(row=3, column=0)
button_2.grid(row=3, column=1)
button_3.grid(row=3, column=2)

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

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

button_0.grid(row=4, column=0)
button_clear.grid(row=4, column=1, columnspan=2)
button_add.grid(row=5, column=0)
button_equal.grid(row=5, column=1, columnspan=2)

button_subtract.grid(row=6, column=0)
button_multiply.grid(row=6, column=1)
button_divide.grid(row=6, column=2)

root.mainloop()
user_121985020
Related