CALCULATOR_APP_USING _TINKTER.py

from tkinter import *
import ast
root = Tk()
 
#writing a function to get button clicked and add it to entry widget
i = 0
# this function gets the number to be added and ads it to input
def get_number(num):
    global i
    # insert the num at index i
    display.insert(i,num)
    # Increment the index
    i+=1
 
def get_operation(operator):
    global i
    length = len(operator)
    display.insert(i,operator)
    i+=length
 
def clear_all():
    display.delete(0, END)
 
 
def calculate():
    entire_string = display.get()
    try:
        #a = parser.expr(entire_string).compile()
        node = ast.parse(entire_string,mode="eval")
        result = eval(compile(node,'<string>','eval'))
        clear_all()
        display.insert(0, result)
    except Exception:
        clear_all()
        display.insert(0, "Error")
 
 
def undo():
    entire_string = display.get()
    if len(entire_string):
        new_string = entire_string[:-1]
        clear_all()
        display.insert(0, new_string)
    else:
        clear_all()
        display.insert(0, "")
 
 
#Let's first add an input field which will be Entry widget
display = Entry(root)
display.grid(row=1,columnspan=6,sticky=W+E)
 
#adding buttons form 1 to 9
numbers =[1,2,3,4,5,6,7,8,9]
counter=0
for x in range(3):
    for y in range(3):
        button_text = numbers[counter]
        button = Button(root,text=button_text,width=2,height=2,command=lambda text=button_text: get_number(text))
        button.grid(row=x+2,column=y)
        counter+=1
 
#adding zero on row 5
button = Button(root,text="0",width=2,height=2,command=lambda:get_number(0))
button.grid(row=5,column=1)
 
 
#adding AC and = button
Button(root, text="AC",width=2,height=2,command=lambda:clear_all()).grid(row=5, column=0)
Button(root, text="=",width=2,height=2,command=lambda :calculate()).grid(row=5, column=2)
 
#adding the delete / undo button
Button(root, text="<-", width=2,height=2, command=lambda: undo()).grid(row=5, column=4)
 
#now column 3 is empty, lets fill it up with operations
count = 0
operations =['+','-','*','/','*3.14',"%","(","**",")","**2"]
for x in range(4):
    for y in range(3):
        if count<len(operations):
            button = Button(root,text=operations[count],width=2,height=2,command= lambda text=operations[count] : get_operation(text))
            count+=1
            button.grid(row=x+2,column=y+3)
 
root.mainloop()