from tkinter import Tk, Label, Button, Entry, X

import tkinter
from tkinter import ttk
from tkinter import messagebox


class Root(Tk):

    def __init__(self):
        super().__init__()

        for x in [ttk.Label, ttk.Button, ttk.Entry, ttk.Checkbutton, ttk.Radiobutton]:
            x(self, text='Some ' + x.__name__).pack(fill=X)
        pb = ttk.Progressbar(self, length=100)
        pb.pack(fill=X)
        pb.step(33)

        ttk.Label(self, text='Select theme:').pack(pady=[50, 10])

        self.style = ttk.Style()
        self.combo = ttk.Combobox(self, values=self.style.theme_names())
        self.combo.pack(pady=[0, 10])
        button = ttk.Button(self, text='Apply')
        button['command'] = self.change_theme
        button.pack(pady=10)

    def change_theme(self):
        content = self.combo.get()
        try:
            self.style.theme_use(content)
        except:
            print("Failed to set theme " + content)


root = Root()
root.mainloop()

from tkinter import *
def btnClick(numbers):
   global operator
   operator = operator + str(numbers)
   text_input.set(operator)
def btnClearDisplay():
   global operator
   operator =""
   text_input.set("")
def btnEqualsInput():
   global operator
   sumup = str(eval(operator))
   text_input.set(sumup)
   operator=""
cal = Tk()
cal.title("your C")
operator = ""
text_input = StringVar()
txtDisplay = Entry(cal, font=('arial', 20, 'bold'), textvariable=text_input, bd=30,
                  insertwidth=4, bg='powder blue', justify='left').grid(columnspan=4)
btn7 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
              text='7', command=lambda:btnClick(7) ).grid(row=1, column=0)
btn8 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
              text='8', command=lambda:btnClick(8)).grid(row=1, column=1)
btn9 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
              text='9', command=lambda:btnClick(9)).grid(row=1, column=2)
addition = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
              text='+', command=lambda:btnClick('+')).grid(row=1, column=3)
btn4 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='4', command=lambda:btnClick(4)).grid(row=2, column=0)
btn5 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='5', command=lambda:btnClick(5)).grid(row=2, column=1)
btn6 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='6', command=lambda:btnClick(6)).grid(row=2, column=2)
subtraction = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='-', command=lambda:btnClick('-')).grid(row=2, column=3)
btn1 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
                text='1', command=lambda:btnClick(1)).grid(row=3, column=0)
btn2 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='2', command=lambda:btnClick(2)).grid(row=3, column=1)
btn3 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='3', command=lambda:btnClick(3)).grid(row=3, column=2)
multiply = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='*', command=lambda:btnClick('*')).grid(row=3, column=3)
btn0 = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='0', command=lambda:btnClick(0)).grid(row=4, column=0)
btnClear = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='C', command= btnClearDisplay).grid(row=4, column=1)
btnEquals = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='=', command=btnEqualsInput).grid(row=4, column=2)
division = Button(cal, padx=16, pady=16, bd=8, fg='black', font=('arial', 20, 'bold'),
             text='/', command=lambda:btnClick('/')).grid(row=4, column=3)
cal.mainloop()