Prog-11 Create a graphical application that accepts user inputs, performs some operation on them, and then writes the output on the screen. For example, write a small calculator. Use the tkinter library.

Python | Simple GUI calculator using Tkinter

Prerequisite : Tkinter Introduction, lambda function

Python offers multiple options for developing GUI (Graphical User Interface). Out of all the GUI methods, tkinter is most commonly used method. It is a standard Python interface to the Tk GUI toolkit shipped with Python. Python with tkinter outputs the fastest and easiest way to create the GUI applications. Creating a GUI using tkinter is an easy task.

To create a tkinter :

1. Importing the module – tkinter
2. Create the main window (container)
3. Add any number of widgets to the main window
4. Apply the event Trigger on the widgets.

Let’s create a GUI based simple calculator using Python Tkinter module, which can perform basic arithmatic operations addition, subtraction, multiplication and division.

Below is the implementation :

# importing Tkinter and math
from tkinter import *
import math
 
# calc class
class calc:
 
    def getandreplace(self):
 
        """replace x with * and ÷ with /"""
        self.expression = self.e.get()
        self.newtext=self.expression.replace('/','/')
        self.newtext=self.newtext.replace('x','*')
 
 
    def equals(self):
        """when the equal button is pressed"""
        self.getandreplace()
        try:
            # evaluate the expression using the eval function
            self.value= eval(self.newtext) 
        except SyntaxError or NameError:
            self.e.delete(0,END)
            self.e.insert(0,'Invalid Input!')
        else:
            self.e.delete(0,END)
            self.e.insert(0,self.value)
 
    def squareroot(self):
        """squareroot method"""
        self.getandreplace()
        try:
            # evaluate the expression using the eval function
            self.value= eval(self.newtext) 
        except SyntaxError or NameError:
            self.e.delete(0,END)
            self.e.insert(0,'Invalid Input!')
        else:
            self.sqrtval=math.sqrt(self.value)
            self.e.delete(0,END)
            self.e.insert(0,self.sqrtval)
 
    def square(self):
        """square method"""
        self.getandreplace()
        try:
            #evaluate the expression using the eval function
            self.value= eval(self.newtext) 
        except SyntaxError or NameError:
            self.e.delete(0,END)
            self.e.insert(0,'Invalid Input!')
        else:
            self.sqval=math.pow(self.value,2)
            self.e.delete(0,END)
            self.e.insert(0,self.sqval)
 
    def clearall(self):
            """when clear button is pressed,clears the text input area"""
            self.e.delete(0,END)
 
    def clear1(self):
            self.txt=self.e.get()[:-1]
            self.e.delete(0,END)
            self.e.insert(0,self.txt)
 
    def action(self,argi):
            """pressed button's value is inserted into the end of the text area"""
            self.e.insert(END,argi)
 
    def __init__(self,master):
            """Constructor method"""
            master.title('Calulator')
            master.geometry()
            self.e = Entry(master)
            self.e.grid(row=0,column=0,columnspan=6,pady=3)
            self.e.focus_set() #Sets focus on the input text area
 
            # Generating Buttons
            Button(master,text="=",width=11,height=3,fg="blue",
                   bg="orange",command=lambda:self.equals()).grid(
                                     row=4, column=4,columnspan=2)
 
            Button(master,text='AC',width=5,height=3,
                          fg="red", bg="light green",
             command=lambda:self.clearall()).grid(row=1, column=4)
 
            Button(master,text='C',width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.clear1()).grid(row=1, column=5)
 
            Button(master,text="+",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action('+')).grid(row=4, column=3)
 
            Button(master,text="x",width=5,height=3,
                    fg="blue",bg="orange",
                    command=lambda:self.action('x')).grid(row=2, column=3)
 
            Button(master,text="-",width=5,height=3,
                    fg="red",bg="light green",
                    command=lambda:self.action('-')).grid(row=3, column=3)
 
            Button(master,text="÷",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action('/')).grid(row=1, column=3)
 
            Button(master,text="%",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.action('%')).grid(row=4, column=2)
 
            Button(master,text="7",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action('7')).grid(row=1, column=0)
 
            Button(master,text="8",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.action(8)).grid(row=1, column=1)
 
            Button(master,text="9",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action(9)).grid(row=1, column=2)
 
            Button(master,text="4",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.action(4)).grid(row=2, column=0)
 
            Button(master,text="5",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action(5)).grid(row=2, column=1)
 
            Button(master,text="6",width=5,height=3,
                   fg="white",bg="blue",
                   command=lambda:self.action(6)).grid(row=2, column=2)
 
            Button(master,text="1",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.action(1)).grid(row=3, column=0)
 
            Button(master,text="2",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action(2)).grid(row=3, column=1)
 
            Button(master,text="3",width=5,height=3,
                   fg="white",bg="blue",
                   command=lambda:self.action(3)).grid(row=3, column=2)
 
            Button(master,text="0",width=5,height=3,
                   fg="white",bg="blue",
                   command=lambda:self.action(0)).grid(row=4, column=0)
 
            Button(master,text=".",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.action('.')).grid(row=4, column=1)
 
            Button(master,text="(",width=5,height=3,
                   fg="white",bg="blue",
                   command=lambda:self.action('(')).grid(row=2, column=4)
 
            Button(master,text=")",width=5,height=3,
                   fg="blue",bg="orange",
                   command=lambda:self.action(')')).grid(row=2, column=5)
 
            Button(master,text="?",width=5,height=3,
                   fg="red",bg="light green",
                   command=lambda:self.squareroot()).grid(row=3, column=4)
 
            Button(master,text="x²",width=5,height=3,
                   fg="white",bg="blue",
                   command=lambda:self.square()).grid(row=3, column=5)
 
# Driver Code
root = Tk()
 
obj=calc(root) # object instantiated
 
root.mainloop()

output