TKInter Python checkbutton state

Question

I am trying to do some work on a text file if certain checkbuttons are checked.

"Populate CheckBoxes"
Label(master, text="Pick at least one index:").grid(row=4, column=1)
Checkbutton(master, text="Short",variable=var1).place(x=5,y=60)
Checkbutton(master, text="Standard",variable=var2).place(x=60,y=60)
Checkbutton(master, text="Long",variable=var3).place(x=130,y=60)

Calling

print("Short: %d,\nStandard: %d,\nLong: %d" % (var1.get(), var2.get(), 
      var3.get()))

prints out 0 or 1 for each variable but when I am trying to use that value to do something it does'nt seem to call the code.

if var2.get(): <--- does this mean if = 1?
    Do something

In if something:, something will be considered True if it is not False, 0, [], '', {}, None, ... Most empty objects (list, dictionary, string, tuple, ...) are considered False, but everything else is considered True (not only 1) — j_4321
– j_4321, Commented Dec 19, 2017 at 10:13

Nae · Accepted Answer · 2017-12-19 10:17:40Z

1

In below example var.get()'s value is printed in command prompt if it's False and updates the lbl['text'] if it's True:

import tkinter

root = tkinter.Tk()

lbl = tkinter.Label(root)
lbl.pack()

var = tkinter.BooleanVar()

def update_lbl():
    global var
    if var.get():
        lbl['text'] = str(var.get())
    else:
        print(var.get())

tkinter.Checkbutton(root, variable=var, command=update_lbl).pack()

root.mainloop()

But below code never prints as "0" and "1" are both True:

import tkinter

root = tkinter.Tk()

lbl = tkinter.Label(root)
lbl.pack()

var = tkinter.StringVar()

def update_lbl():
    global var
    if var.get():
        lbl['text'] = str(var.get())
    else:
        print(var.get())

tkinter.Checkbutton(root, variable=var, command=update_lbl).pack()

root.mainloop()

edited Dec 19, 2017 at 10:17

answered Dec 19, 2017 at 10:13

Nae

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4 Comments

Jon Lavercombe Over a year ago

Thanks, what is the reason though that when i've clicked the var2 checkbox its not the completing the action of the if statement?

Nae Over a year ago

@JonLavercombe are they objects of StringVar?

Jon Lavercombe Over a year ago

No they are just exactly as listed above, so if i convert them to string... something like if str(var2.get()):

Nae Over a year ago

@JonLavercombe var1, var2, var3 should all be tkinter.BooleanVar or at worst tkinter.IntVar otherwise they may act unpredictably.

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