Answer
code
Work Step by Step
# 14.6 (Tkinter: Count the occurrences of each letter) Rewrite Listing 14.5 using a GUI
# program to let the user enter the URL from an entry field, as shown in Figure 14.5.
# Clicking the Show Result button displays the result in a text widget. You need to
# display a message in a message box if the URL does not exist.
import urllib.request
from tkinter import *
from tkinter import messagebox
def showResult():
try:
filename = urllib.request.urlopen(url.get())
infile = filename.read().decode()
counts = 26 * [0] # Create and initialize counts
for line in infile:
# Invoke the countLetters function to count each letter
countLetters(line.lower(), counts)
# Display results
for i in range(len(counts)):
if counts[i] != 0:
text.insert(END, chr(ord('a') + i) + " appears " + str(counts[i])
+ (" time" if counts[i] == 1 else " times") + "\n")
except IOError:
messagebox.showwarning("Analyze URL",
"URL " + url.get() + " does not exist")
# Count each letter in the string
def countLetters(line, counts):
for ch in line:
if ch.isalpha():
counts[ord(ch) - ord('a')] += 1
window = Tk() # Create a window
frame1 = Frame(window) # Hold four labels for displaying cards
frame1.pack()
scrollbar = Scrollbar(frame1)
scrollbar.pack(side=RIGHT, fill=Y)
text = Text(frame1, width=40, height=10, wrap=WORD,
yscrollcommand=scrollbar.set)
text.pack()
scrollbar.config(command=text.yview)
frame2 = Frame(window) # Hold four labels for displaying cards
frame2.pack()
Label(frame2, text="Enter a URL: ").pack(side=LEFT)
url = StringVar()
Entry(frame2, width=30, textvariable=url).pack(side=LEFT)
Button(frame2, text="Show Result", command=showResult).pack(side=LEFT)
window.mainloop() # Create an event loop
