from tkinter import *
import sys
class Calculator:
    def __init__(self, master):
        self.master = master
        master.title("Simple Calculator")

        self.frame1 = Frame(master)
        self.frame1.option_add("*Font", "arial 20 bold")
        self.frame1.pack(expand = YES, fill = BOTH)

        self.result = StringVar()
        self.result.set("")

        self.entry = Entry(self.frame1, relief=FLAT, textvariable=self.result, justify="right", bd=5, bg="lightblue")
        self.entry.pack(side=TOP)


        self.frame2 = Frame(master, borderwidth = 10, bd = 1, bg='grey')
        self.frame2.pack(side=TOP, expand = YES, fill = BOTH)

        self.btnClear = Button(self.frame2, text = "C", width = 4, command = self.resetResult)
        self.btnClear.grid(column = 0, row = 0)
        self.btnCE = Button(self.frame2, text = "CE", width = 4, command = self.resetResult)
        self.btnCE.grid(column = 1, row = 0)
        self.btnSquare = Button(self.frame2, text = "x^2", width = 4, command = self.square)
        self.btnSquare.grid(column = 2, row = 0)
        self.btnDiv = Button(self.frame2, text = "/", width = 4, command = lambda:self.changeOp("/"))
        self.btnDiv.grid(column = 3, row = 0)

        for b in "123456789":
            btnNum = Button(self.frame2, text = b, width = 4, command = lambda:self.numberUpdate(b))
            btnNum.grid(column=(int(b)-1)%3, row=int((int(b)-1)/3)+1)

    def resetResult(self):
        pass

    def square(self):
        pass

    def changeOp(self, op):
        pass
    
    def printDemo(self):
        print("This is demo")

root = Tk()
my_gui = Calculator(root)
root.mainloop()