Python Programming String Handling Functions

Question

So, I'm a beginner to programming. I am trying to create a program where the user can input a sentence and the program will tell the user how many letters are in that sentence.

counter=0
wrd=raw_input("Please enter a short sentence.")
if wrd.isalpha():
counter=counter+1
print "You have" + str(counter) +"in your sentence."

When I enter this, my output is blank. What is my mistake in this program?

• martianwars: You haven't indented counter=counter+1 I think. Besides this, you aren't exactly using a loop
• Chris: Can you use len()? That's the easiest and fastest way to do what you describe. Of course you'd still need to filter out the all the non-letters from your sentence.

Answer 1

You need to indent code inside if blocks. In the code you have provided, you've forgotten to indent counter = counter + 1.

You are missing a loop across all characters of wrd. Try this instead,

counter = 0
wrd = raw_input("Please enter a short sentence.")
# Iterate over every character in string
for letter in wrd:
 # Check if the letter is an alphabet
 if letter.isalpha():
 # Increment counter only in this condition
 counter += 1
print "You have " + str(counter) + " in your sentence."

Answer 2

First of all as @kalpesh mentioned, the statement counter=counter+1 should be indented.

Second of all, you need to iterate over the entire string entered and then count the number of characters or whatever the logic you need.

counter=0
wrd=raw_input("Please enter a short sentence.")
for i in wrd:
 if i.isalpha():
 counter = counter+1
print "You have " + str(counter) +"in your sentence."

Once you start learning more, then you can use the below code,

counter=[]
count = 0
wrd=raw_input("Please enter a short sentence.")
counter = [len(i) for i in wrd.split() if i.isalpha()]
print "You have " + str(sum(counter)) +"in your sentence."

I am just splitting the word and then checking if it is alpha or not and using the list comprehension to iterate over the string entered.

Answer 3

wrd.isalpha() returns a boolean (true or false). So if the function returns true, counter=counter+1 will be called once (and only once). You need to iterate through every letter of wrd and call isalpha() on each letter.

Answer 4

You could always remove the spaces from your sentence using replace() then use len() to get how many characters are in the sentence.

For example:

sentence = input("Type in a sentence: ") # Ask the user to input a sentence
sentence = sentence.replace(" ", "") # Replace the spaces in the sentence with nothing
print("Your sentence is " + str(len(sentence)) + " characters long") # Use len() to print out number of letters in the sentence