Simple GUI calculator using Tkinter

Simple GUI calculator using Tkinter in Python

Here we will learn to build a simple GUI (Graphical User Interface) calculator using tkinter module in Python. You don't need to install tkinter externally, it comes with Python.

Python Tkinter

The tkinter package is the standard Python interface to the Tk GUI toolkit.

With this module we can build Python based GUI applications.

Simple GUI calculator using Tkinter

Program

#Simple Calculator

from tkinter import *

#Creating main window

root = Tk()

# Giving title to the window

root.title("Simple Calculator")

# Some useful functions

# Function used to display values on to the screen Entry box

def click(numChar):

if display.get() == "Invalid input":

display.delete(0, END)

display.insert(END, numChar)

# Function executes when '=' button is pressed

# Evaluates the value and gives out the result

def EVAL():

try:

value = eval(display.get())

except:

value = "Invalid input"

display.delete(0, END)

display.insert(0, value)

#Creating Buttons

display = Entry(root, width=45, borderwidth=6)

c0 = Button(root, text="0", padx=30, pady=30, command= lambda: click(0))

c1 = Button(root, text="1", padx=30, pady=30, command= lambda: click(1))

c2 = Button(root, text="2", padx=30, pady=30, command= lambda: click(2))

c3 = Button(root, text="3", padx=30, pady=30, command= lambda: click(3))

c4 = Button(root, text="4", padx=30, pady=30, command= lambda: click(4))

c5 = Button(root, text="5", padx=30, pady=30, command= lambda: click(5))

c6 = Button(root, text="6", padx=30, pady=30, command= lambda: click(6))

c7 = Button(root, text="7", padx=30, pady=30, command= lambda: click(7))

c8 = Button(root, text="8", padx=30, pady=30, command= lambda: click(8))

c9 = Button(root, text="9", padx=30, pady=30, command= lambda: click(9))

add = Button(root, text="+", padx=30, pady=30, command= lambda: click('+'))

sub = Button(root, text="-", padx=30, pady=30, command= lambda: click('-'))

mul = Button(root, text="*", padx=30, pady=30, command= lambda: click('*'))

div = Button(root, text="/", padx=30, pady=30, command= lambda: click('/'))

# '=' button which will call EVAL function

equal = Button(root, text="=", padx=66, pady=30, command=EVAL)

# 'clear' button, which will clear all the values in the entry box

clear = Button(root, text="Clear", padx=95, pady=30, command=lambda: display.delete(0, END))

# Button to delete last value

cut = Button(root, text="<=", padx=30, pady=30, command= lambda: display.delete(len(display.get())-1, END))

#Providing position to the buttons

display.grid(row=0, column=0, columnspan=4, padx=10, pady=10)

c0.grid(row=4, column=0)

c1.grid(row=3, column=0)

c2.grid(row=3, column=1)

c3.grid(row=3, column=2)

c4.grid(row=2, column=0)

c5.grid(row=2, column=1)

c6.grid(row=2, column=2)

c7.grid(row=1, column=0)

c8.grid(row=1, column=1)

c9.grid(row=1, column=2)

add.grid(row=4, column=3)

sub.grid(row=3, column=3)

mul.grid(row=2, column=3)

div.grid(row=1, column=3)

equal.grid(row=4, column=1, columnspan=2)

clear.grid(row=5, column=0, columnspan=3)

cut.grid(row=5, column=3)

root.mainloop()

Output

        

Module and methods used in the program

• tkinter
• Tk()
• title()
• Entry()
• Button()