The code

Straight from labs/course-3-python/17_tkinter_input.py, unchanged.

"""Experiment 17: A Tkinter program with Label, Entry and Button widgets that
takes user input and displays it.

Syllabus: Course 3, Unit 5 -- GUI programming with Tkinter.

Run for the lab page under a virtual display (xvfb-run) by _drive_17_tkinter_input.py,
which types into the form, presses its buttons and asserts what the window shows. Run it
on your own machine with `python3 17_tkinter_input.py`; tkinter ships with the standard
Windows and macOS Python installers, and is `sudo apt install python3-tk` on Debian/Ubuntu.
"""

import tkinter as tk
from tkinter import messagebox


class GreetingApp:
    def __init__(self, root):
        self.root = root
        root.title("Student Input Form")
        root.geometry("420x260")

        # Step 1: Labels and Entry widgets
        tk.Label(root, text="Student Details", font=("Arial", 14, "bold")
                 ).grid(row=0, column=0, columnspan=2, pady=10)

        tk.Label(root, text="Name:").grid(row=1, column=0, sticky="e", padx=5,
                                          pady=5)
        self.name_entry = tk.Entry(root, width=25)
        self.name_entry.grid(row=1, column=1, padx=5, pady=5)

        tk.Label(root, text="Roll number:").grid(row=2, column=0, sticky="e",
                                                 padx=5, pady=5)
        self.roll_entry = tk.Entry(root, width=25)
        self.roll_entry.grid(row=2, column=1, padx=5, pady=5)

        tk.Label(root, text="Course:").grid(row=3, column=0, sticky="e",
                                            padx=5, pady=5)
        self.course_entry = tk.Entry(root, width=25)
        self.course_entry.grid(row=3, column=1, padx=5, pady=5)

        # Step 2: Buttons, bound to their handlers
        tk.Button(root, text="Submit", width=10, command=self.submit
                  ).grid(row=4, column=0, pady=15)
        tk.Button(root, text="Clear", width=10, command=self.clear
                  ).grid(row=4, column=1, pady=15)

        # Step 3: The output label
        self.output = tk.Label(root, text="", font=("Arial", 11), fg="darkblue",
                               wraplength=380, justify="left")
        self.output.grid(row=5, column=0, columnspan=2)

    # Step 4: The Submit handler
    def submit(self):
        """Event handler for the Submit button."""
        name = self.name_entry.get().strip()
        roll = self.roll_entry.get().strip()
        course = self.course_entry.get().strip()

        if not name or not roll:
            messagebox.showwarning("Missing data",
                                   "Name and roll number are required")
            return

        self.output.config(
            text=f"Name   : {name}\nRoll   : {roll}\nCourse : {course}")

    # Step 5: The Clear handler
    def clear(self):
        """Event handler for the Clear button."""
        for entry in (self.name_entry, self.roll_entry, self.course_entry):
            entry.delete(0, tk.END)
        self.output.config(text="")


if __name__ == "__main__":
    # Step 6: Start the event loop
    window = tk.Tk()
    GreetingApp(window)
    window.mainloop()          # starts the event loop; blocks until closed

Where this sits

One experiment from the Python Programming and Data Structures lab. The rest of them, and the theory behind this one, are on the lab page.