Create an Awesome Calculator using Python – Python Projects

eval(expression, globals=None, locals=None)

"""
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Developer: Krishna Kaushal
Youtube: https://youtube.com/xalgord
github: https://github.com/xalgord
Instagram: https://instagram.com/xalgord
website: https://xalgord.in
###################################
"""

# Importing necessary packages
import tkinter as tk
from tkinter import *

# Defining CreateWidgets() function to create necessary tkinter widgets
def CreateWidgets():
    CalcDisplay = Entry(root, bd=10, justify="right", font=("arial", 20, "bold"), textvariable=d_value, bg="cyan3")
    CalcDisplay.grid(row=0, column=0, columnspan=5)

    B_AllClear = Button(root, text="AC", bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=allclearEntry)
    B_AllClear.grid(row=1, column=0, padx=5, pady=5)

    B_Clear = Button(root, text="C", bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=clearEntry)
    B_Clear.grid(row=1, column=1, padx=5, pady=5)

    B_2 = Button(root, text='%', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('%'))
    B_2.grid(row=1, column=2, padx=5, pady=5)

    B_D = Button(root, text='/', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('/'))
    B_D.grid(row=1, column=3, padx=5, pady=5)

    B_7 = Button(root, text='7', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(7))
    B_7.grid(row=2, column=0, padx=5, pady=5)

    B_8 = Button(root, text='8', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(8))
    B_8.grid(row=2, column=1, padx=5, pady=5)

    B_9 = Button(root, text='9', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(9))
    B_9.grid(row=2, column=2, padx=5, pady=5)

    B_M = Button(root, text='*', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('*'))
    B_M.grid(row=2, column=3, padx=5, pady=5)

    B_4 = Button(root, text='4', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(4))
    B_4.grid(row=3, column=0, padx=5, pady=5)

    B_5 = Button(root, text='5', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(5))
    B_5.grid(row=3, column=1, padx=5, pady=5)

    B_6 = Button(root, text='6', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(6))
    B_6.grid(row=3, column=2, padx=5, pady=5)

    B_D = Button(root, text='-', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('-'))
    B_D.grid(row=3, column=3, padx=5, pady=5)

    B_1 = Button(root, text='1', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(1))
    B_1.grid(row=4, column=0, padx=5, pady=5)

    B_2 = Button(root, text='2', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(2))
    B_2.grid(row=4, column=1, padx=5, pady=5)

    B_3 = Button(root, text='3', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick(3))
    B_3.grid(row=4, column=2, padx=5, pady=5)

    B_A = Button(root, text='+', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('+'))
    B_A.grid(row=4, column=3, padx=5, pady=5)

    B_0 = Button(root, text='0', bd=5,  font=("arial", 20, "bold"), width=10, height=2, command=lambda : buttonClick(0))
    B_0.grid(row=5, column=0, padx=5, pady=5, columnspan=2)

    B_DP = Button(root, text='.', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=lambda : buttonClick('.'))
    B_DP.grid(row=5, column=2, padx=5, pady=5)

    B_E = Button(root, text='=', bd=5,  font=("arial", 20, "bold"), width=4, height=2, command=calculateResult)
    B_E.grid(row=5, column=3, padx=5, pady=5)

# Defining the buttonClick() function with c_input to fetch user pressed button's value
def buttonClick(c_input):
    # Declaring the c_expression variable as global
    global c_expression
    # Concatenating and storing the c_expression value with the user pressed button's value
    c_expression = c_expression + str(c_input)
    # Setting the Entry Widget value to that of the c_operatot value
    d_value.set(c_expression)

# Defining the Browse() to save the file
def calculateResult():
    global c_expression
    # Calling the eval() with c_expression as input which has expression to be evaluated
    # eval() parses the expression passed to it and run python expression within it
    result = str(eval(c_expression))
    # Setting the Entry Widget value to that of the result variable's value
    d_value.set(result)

# Defining the allclearEntry() to clear the inputs in the Entry Widget
def allclearEntry():
    global c_expression
    # Setting the c_expression variable to empty string and diplaying it in the Widget
    c_expression = ""
    d_value.set(c_expression)

# Defining the clearEntry() to clear one input entry from the Entry Widget
def clearEntry():
    # Declaring the c_expression & d_value variable as global
    global c_expression, d_value
    # Removing the last character from the Entry Widget Input
    cleared_value =  d_value.get()[:-1]
    # Setting the c_expression variable to the d_value variable's value
    c_expression = cleared_value
    d_value.set(c_expression)

# Creating object root of tk
root = tk.Tk()

# Setting the title, window size, background color and disabling the resizing property
root.title('PyCalculator')
root.resizable(False, False)
root.configure(background='cyan4')

# Creating tkinter variable
d_value = StringVar()
c_expression = ""

CreateWidgets()

# Defining infinite loop to run application
root.mainloop()