Simple calculator using python gui tkinter

Question

I am trying to make a simple calculator that gives square and square root with using Python 2.7.10 with GUI but it doesn't work I can't figure out what is the problem. I receive this error:

> Exception in Tkinter callback Traceback (most recent call last): File
> "C:\Python27\lib\lib-tk\Tkinter.py", line 1536, in call return
> self.func(*args) File "C:/Users/Ali/Desktop/simplecalc.py", line 5, in
> do_sqrt root = x**0.5 TypeError: unsupported operand type(s) for ** or
> pow(): 'str' and 'float'

import Tkinter    
import tkMessageBox

def do_sqrt():
    root = x**0.5
    tkMessageBox.showinfo("Square Root = ", x)

def do_square():
    square = x**2
    tkMessageBox.showinfo("Square = ", x)

main_window = Tkinter.Tk()
main_window.title("Simple Calc")
number_input = (Tkinter.Entry(main_window))
x = number_input.get()
button_sqrt = Tkinter.Button(main_window, text = "Square Root", command = do_sqrt)
button_sqrt.pack()
button_square = Tkinter.Button(main_window, text = "Square", command =     do_square)
button_square.pack()
number_input.pack()

main_window.mainloop()

Welcome to Stack Overflow! Please add more details to clarify the question you are asking and provide necessary context. — intcreator
– intcreator, Commented Jan 29, 2016 at 21:47
Window pops and I enter a number to the box then click to square root button or square button but then I get this error. Exception in Tkinter callback Traceback (most recent call last): File "C:\Python27\lib\lib-tk\Tkinter.py", line 1536, in call return self.func(*args) File "C:/Users/Ali/Desktop/simplecalc.py", line 5, in do_sqrt root = x**0.5 TypeError: unsupported operand type(s) for ** or pow(): 'str' and 'float' — Ali Beyit
– Ali Beyit, Commented Jan 29, 2016 at 21:49
@AliBeyit Please edit your question to add those details. They're very hard to read in the comments. — intcreator
– intcreator, Commented Jan 29, 2016 at 21:50

midori · Accepted Answer · 2016-01-29 22:25:16Z

1

You are reading the string from the entry and trying to perform some math. And you are not using root and square variables.

import Tkinter
import tkMessageBox


def do_sqrt():
    root = float(number_input.get())**0.5
    tkMessageBox.showinfo("Square Root = ", root)


def do_square():
    square = float(number_input.get())**2
    tkMessageBox.showinfo("Square = ", square)

main_window = Tkinter.Tk()
main_window.title("Simple Calc")
number_input = Tkinter.Entry(main_window)
button_sqrt = Tkinter.Button(main_window, text="Square Root", command=do_sqrt)
button_sqrt.pack()
button_square = Tkinter.Button(main_window, text="Square", command=do_square)
button_square.pack()
number_input.pack()

main_window.mainloop()

edited Jan 29, 2016 at 22:25

answered Jan 29, 2016 at 22:14

midori

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2 Comments

Ali Beyit Over a year ago

Oh thanks god. I thought I tried this but forgot to write float around the number_input.get(). Thanks a lot for the help

midori Over a year ago

you are welcome. I would also suggest to stick with OOP approach in writing in tkinter, it's shorter and easier to reuse and structure the gui app.

Jared Goguen · Accepted Answer · 2016-01-29 21:49:10Z

1

The line x = number_input.get() will return a string, but you are trying to use it as a number. Use the line x = float(number_input.get()) instead. This would have been clear if you included the error printout:

TypeError: unsupported operand type(s) for ** or pow(): 'str' and 'float'

Also, it would be much better to avoid global variables, but that's another issue for another day.

answered Jan 29, 2016 at 21:49

Jared Goguen

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3 Comments

Ali Beyit Over a year ago

Thanks for the advice but I tried it also. It gives this error. ValueError: could not convert string to float:

Jared Goguen Over a year ago

Yeah, if your input is empty or has non-numeric values, it's not going to be able to be converted into a float.

Ali Beyit Over a year ago

But I input numeric values still gives the same error

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