Chapter 13: Problem 18

How can you use an intvar object to determine whether a checkbutton has been selected?

Short Answer

Expert verified

#Answer# To use an IntVar object to determine the state of a checkbutton in tkinter, first import the tkinter library and create an application window. Then, initialize the IntVar object and create a Checkbutton widget, linking it to the IntVar object using the "variable" parameter. Create a function that reads the value stored in the IntVar object and prints whether the checkbutton is selected or not. Add a button to trigger the function and run the application. The IntVar object holds value 1 if the checkbutton is selected, and 0 if not selected.

Step by step solution

Understand IntVar and Checkbutton

In Python, the tkinter library provides the functionality for creating GUI applications. IntVar is a variable class provided by the tkinter library that can hold integer values. A Checkbutton is a simple widget in tkinter, which allows users to select or deselect an option by ticking or unticking a box. The IntVar object can be linked to a checkbutton to track whether the button is selected or not. When linked, the IntVar object will hold the value 1 if the checkbutton is selected, and 0 if not selected.

Import Required Libraries

To create a simple tkinter application with Checkbutton and IntVar, you will need to import the tkinter library. You can do this by adding the following line in your code: ```python import tkinter as tk ```

Create Application Window

Now, you need to create the main application window for your program. You can do this by initiating the tk.Tk() class: ```python root = tk.Tk() ```

Initialize IntVar for Checkbutton

To track the state of the checkbutton, you should create an IntVar object before creating the Checkbutton widget. ```python checkbox_var = tk.IntVar() ```

Create the Checkbutton Widget

Create a Checkbutton widget using the `tk.Checkbutton` class and link it to the IntVar object by setting the "variable" parameter to the IntVar object you created earlier: ```python checkbox = tk.Checkbutton(root, text="Select option", variable=checkbox_var) ```

Position the Checkbutton

You need to position the Checkbutton on your application window using the pack() method: ```python checkbox.pack() ```

Create a Function to Determine Checkbutton State

Create a simple function that reads the value stored in the IntVar object and prints whether the checkbutton is selected or not: ```python def check_state(): if checkbox_var.get() == 1: print("Checkbutton is selected") else: print("Checkbutton is not selected") ```

Create a Button to Check the State

To trigger the check_state function, create a Button widget using the tk.Button class and connect it to the function using the "command" parameter: ```python button = tk.Button(root, text="Check state", command=check_state) button.pack() ```

Run the Application

Finally, run the application window's main event loop using the following line: ```python root.mainloop() ``` Now, run your code. If the checkbutton is selected, the terminal will print "Checkbutton is selected". If not, it will print "Checkbutton is not selected".

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How can you use an intvar object to determine whether a checkbutton has been selected?

Short Answer

Step by step solution

Understand IntVar and Checkbutton

Import Required Libraries

Create Application Window

Initialize IntVar for Checkbutton

Create the Checkbutton Widget

Position the Checkbutton

Create a Function to Determine Checkbutton State

Create a Button to Check the State

Run the Application

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