For this assignment you will use Tkinter to build a simple graphical calculator.

Question

For this assignment you will use Tkinter to build a simple graphical calculator. The calculator should emulate a very simple cheap four function (+, -, x, /) calculator. It should be able to perform the four basic operations -- addition, subtraction, multiplication, and division -- on two values. The user would enter a number, then click on a math operator, enter another number, then click the equal sign. The user should be able to enter longer sequences of operations like "1 + 2 - 3 =" However, no algebraic manipulations are necessary -- operations can be performed immediately. There should be a +/- button to allow changes to the sign of a number and a clear button to erase a value. Examples: User types "1 + 2 =" -- the sum is displayed when the "=" key is clicked User types "10 - 4 + 2 =" -- the partial answer 6 is displayed when the "+" sign is clicked and the final answer 8 is displayed when the "=" is clicked User types "42 - 40 x 10 =" -- the partial answer of "42 - 40" is computed when the 'x" is clicked (not algebraic execution), then the answer 20 is displayed when the "=" is clicked Components of the calculator: -- numeric display -- number buttons (0-9) -- decimal pt button (.) -- +/- button -- four math operator buttons (+, -, x, /) -- an equals button (=) -- a clear button

Explanation / Answer

#-*-coding: utf-8-*-
from Tkinter import *
import math

class calc:
def getandreplace(self):
"""replace x with * and ÷ with /"""

self.expression = self.e.get()
self.newtext=self.expression.replace(self.newdiv,'/')
self.newtext=self.newtext.replace('x','*')

def equals(self):
"""when the equal button is pressed"""

self.getandreplace()
try:
  self.value= eval(self.newtext) #evaluate the expression using the eval function
except SyntaxError or NameErrror:
  self.e.delete(0,END)
  self.e.insert(0,'Invalid Input!')
else:
  self.e.delete(0,END)
  self.e.insert(0,self.value)



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
   
self.div='÷'
self.newdiv=self.div.decode('utf-8')

#Generating Buttons
Button(master,text="=",width=10,command=lambda:self.equals()).grid(row=4, column=4,columnspan=2)
Button(master,text='AC',width=3,command=lambda:self.clearall()).grid(row=1, column=4)
Button(master,text='C',width=3,command=lambda:self.clear1()).grid(row=1, column=5)
Button(master,text="+",width=3,command=lambda:self.action('+')).grid(row=4, column=3)
Button(master,text="x",width=3,command=lambda:self.action('x')).grid(row=2, column=3)
Button(master,text="-",width=3,command=lambda:self.action('-')).grid(row=3, column=3)
Button(master,text="÷",width=3,command=lambda:self.action(self.newdiv)).grid(row=1, column=3)
Button(master,text="%",width=3,command=lambda:self.action('%')).grid(row=4, column=2)
Button(master,text="7",width=3,command=lambda:self.action('7')).grid(row=1, column=0)
Button(master,text="8",width=3,command=lambda:self.action(8)).grid(row=1, column=1)
Button(master,text="9",width=3,command=lambda:self.action(9)).grid(row=1, column=2)
Button(master,text="4",width=3,command=lambda:self.action(4)).grid(row=2, column=0)
Button(master,text="5",width=3,command=lambda:self.action(5)).grid(row=2, column=1)
Button(master,text="6",width=3,command=lambda:self.action(6)).grid(row=2, column=2)
Button(master,text="1",width=3,command=lambda:self.action(1)).grid(row=3, column=0)
Button(master,text="2",width=3,command=lambda:self.action(2)).grid(row=3, column=1)
Button(master,text="3",width=3,command=lambda:self.action(3)).grid(row=3, column=2)
Button(master,text="0",width=3,command=lambda:self.action(0)).grid(row=4, column=0)
Button(master,text=".",width=3,command=lambda:self.action('.')).grid(row=4, column=1)
Button(master,text="(",width=3,command=lambda:self.action('(')).grid(row=2, column=4)
Button(master,text=")",width=3,command=lambda:self.action(')')).grid(row=2, column=5)

#Main
root = Tk()
obj=calc(root) #object instantiated
root.mainloop()

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.