'''
20210923
R. Dawes
'''

import tkinter as tk

window = tk.Tk()
window.title("Compare two numbers")
window.geometry("1200x800")


label_1 = tk.Label(window,text="Enter x in this box")
#add an entry box to accept input
entry_1 = tk.Entry(window, width = 10)

label_2 = tk.Label(window,text="Enter y in this box")
#add an entry box to accept input
entry_2 = tk.Entry(window, width = 10)


#add a text box to show output
text_1 = tk.Text(window,height = 10, width = 30)

#add a button - a clickable object

#add a function to react to button_1

def button_1_clicked():
   x = entry_1.get()                      # this is how we get input the user entered in the 
   y = entry_2.get()                      # Entry boxes on the screen
   text_1.delete(1.0, tk.END)       # tk.END is a special object that always reaches the 
                                                    # last occupied location in a Text widget
                                                    # This instruction clears the Text box
                                                    
# In class I mentioned that I did not know why the first occupied location in a Text
# widget is referenced by "1.0" ....  but now I do know!   In a Text widget, the lines are
# numbered starting at 1, and the columns are numbered starting at 0.   So the "1.0" is 
# not a floating point number.  The number before the decimal point indicates the line
# number, and the number after the decimal point indicates the column number.  So
# "1.0" means "row 1, column 0", which in this case - unlike almost EVERY other 
# instance of indexing in Python, including the tkinter layout grid - means the 
# first position in the first row.

# This is the strangest thing I have seen in a long time.  First, why would you start
# line numbers at 1 and column numbers at 0?  Second, why would you use a decimal point
# instead of a comma to separate the row and column values?

   if (x < y):
      text_1.insert(tk.END, x + " < " + y)
   elif (x > y):
      text_1.insert(tk.END, x + " > " + y)
   else:
      text_1.insert(tk.END, x + " = " + y)

# This function gives the expected output when the input is 8 and 9, but 
# if the input is 8 and 10, it seems to get the comparison wrong.  Why?  See the
# next example to find out.


button_1 = tk.Button(window, text = "Compare Them", command = button_1_clicked)


label_1.grid(row = 0, column = 0)
entry_1.grid(row = 0, column = 1)
label_2.grid(row = 1, column = 0)
entry_2.grid(row = 1, column = 1)
button_1.grid(row = 2, column = 0)
text_1.grid(row = 2, column = 2)

window.mainloop()