CODEWITHSUNDEEP
pythontkinterpython-3.4
rharper
rharper

Reputation: 565

Tkinter Entry widget float number

I'm making a BMI calculator just to get my head around tkinter. I am stuck on this one part- how do I make it so it gets a float number from the entry widget?

Here are some snippets of my code

Getting entry inputs (this is in a function called calculateBMI)

hgtval = float(height.get())
wgtval = float(weight.get())

Here is creating the variables and making the entry boxes.

hgt = StringVar()
wgt = StringVar()

height = Entry(root, stringvariable=hgt).grid(row=1, column=2)
weight = Entry(root, stringvariable=wgt).grid(row=2, column=2)

Running the whole program I am given this error:

C:\Python34\python.exe I:/programming/project/bmi.py
Traceback (most recent call last):
  File "I:/programming/project/bmi.py", line 35, in <module>
    height = Entry(root, stringvariable=hgt).grid(row=1, column=2)
  File "C:\Python34\lib\tkinter\__init__.py", line 2478, in __init__
    Widget.__init__(self, master, 'entry', cnf, kw)
  File "C:\Python34\lib\tkinter\__init__.py", line 2086, in __init__
    (widgetName, self._w) + extra + self._options(cnf))
_tkinter.TclError: unknown option "-stringvariable"

Upvotes: 2

Views: 3988

Answers (1)

Bryan Oakley
Bryan Oakley

Reputation: 386362

The option is textvariable, not stringvariable.

Unrelated to this problem, when you do height = Entry(...).grid(...), height will always be None since that is what .grid(...) returns. It is a best practice to separate widget creation from widget layout.

When you do that (separating creation from layout) you don't actually need to use StringVars, since you can get the value directly from the widget itself (eg: hgtval = float(height.get())

Upvotes: 4

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