Simple calculator using python and tkinter

 from re import sub

from tkinter import *

#creating a window

root =  Tk()

#decale the default variable

calc = ""

#definig the function

def addi():

    global calc

    calc += "+"

    pop['text'] = calc

def subi():

    global calc

    calc += "-"

    pop['text'] = calc

def divi():

    global calc

    calc += "/"

    pop['text'] = calc

def multipl():

    global calc

    calc += "*"

    pop['text'] = calc

def ze():

    global calc

    calc += "0"

    pop['text'] = calc

def on():

    global calc

    calc += "1"

    pop['text'] = calc

def tw():

    global calc

    calc += "2"

    pop['text'] = calc

def th():

    global calc

    calc += "3"

    pop['text'] = calc

def fo():

    global calc

    calc += "4"

    pop['text'] = calc

def fi():

    global calc

    calc += "5"

    pop['text'] = calc

def si():

    global calc

    calc += "6"

    pop['text'] = calc

def se():

    global calc

    calc += "7"

    pop['text'] = calc

def ei():

    global calc

    calc += "8"

    pop['text'] = calc

def ni():

    global calc

    calc += "9"

    pop['text'] = calc

def decii():

    global calc

    calc += "."

    pop["text"] = calc

def evali():

    global calc

    try:

        calc = eval(calc)

        pop["text"] = calc

        calc = ""

    except:

        pop['text'] = "AN ERROR OCCURRED"

        calc = ""

def cleari():

    global calc

    calc = ""

    pop["text"] = calc

#naming the window

root.title("A SIMPLE CALCULATOR")

#label and entry field

m = Label(root, text="CALCULATOR", font=(25))

pop = Label(root, text='', font=(50))

#operators box

adding = Button(root, text="+",height=2, width=5, command=addi)

subtracting = Button(root, text="-",height=2, width=5, command=subi)

dividing = Button(root, text="/",height=2, width=5, command=divi)

multiplying = Button(root, text="*",height=2, width=5, command=multipl)

equating = Button(root, text="=", height=10, width=13, command=evali)

#numbers

nine = Button(root, text="9", height=2, width=5, command=ni)

eight = Button(root, text="8", height=2, width=5, command=ei)

seven = Button(root, text="7", height=2, width=5, command=se)

six = Button(root, text="6", height=2, width=5, command=si)

five = Button(root, text="5", height=2, width=5, command=fi)

four = Button(root, text="4", height=2, width=5, command=fo)

three = Button(root, text="3", height=2, width=5, command=th)

two = Button(root, text="2", height=2, width=5, command=tw)

one = Button(root, text="1", height=2, width=5, command=on)

zero = Button(root, text="0", height=2, width=5, command=ze)

ccc = Button(root, text="C", height=2, width=5, command=cleari)

deci = Button(root, text=".", height=2, width=5, command=decii)

#placing on screen

m.place(x=190, y=0)

pop.place(x=100, y=30)

#placiing operators

adding.place(x=100, y=60)

subtracting.place(x=150, y=60)

dividing.place(x=200, y=60)

multiplying.place(x=250, y=60)

equating.place(x=300, y=60)

#placing digits

nine.place(x=100, y=100)

eight.place(x=150, y=100)

seven.place(x=200, y=100)

six.place(x=250, y=100)

five.place(x=100, y=140)

four.place(x=150, y=140)

three.place(x=200, y=140)

two.place(x=250, y=140)

ccc.place(x=100, y=180)

one.place(x=150, y=180)

zero.place(x=200, y=180)

deci.place(x=250, y=180)

root.resizable(False, False)

root.geometry("500x500")

root.mainloop()

Problem 2 - Cafe menu

 Write a program that first displays a simple cafe menu (see example below), asks the user to enter the number of a choice, and either prints the appropriate action OR prints an error message that their choice was not valid.

Example output:

1. Soup and salad

2. Pasta with meat sauce

3. Chef's special

Which number would you like to order? 2

One Pasta with meat sauce coming right up!

Another example output:

1. Soup and salad

2. Pasta with meat sauce

3. Chef's special

Which number would you like to order? 5

Sorry, that is not a valid choice

Registration System

 You are making a registration form for a website.

The form has a name field, which should be more than 3 characters long.

Any name that has less than 4 characters is invalid.

Complete the code to take the name as input, and raise an exception if the name is invalid, outputting "Invalid Name". Output "Account Created" if the name is valid.

Sample Input

abc

Sample Output

Invalid Name