CODEWITHSUNDEEP
python
CNNC
CNNC

Reputation: 33

Python - Can't get "string.isalnum():" to work properly

I cannot get the code below to work properly. It works if the user enters numbers for the name and it prints the theName.isdigit. But if the user enters both numbers and letters, it accepts this and moves onto a welcome message that follows. Looking at this, is there a reason you can find why theName.isalnum is not working here but the one above is?

theName = raw_input ("What is your name?? ")

while theName.isdigit ():
    if theName.isdigit ():
        print "What kind of real name has just numbers in it?? Try again..."
    elif theName.isalnum ():
        print "What kind of name has any numbers in it?? Please try again..."
    elif theName.isalpha ():
        print "Ok, great"
        break
    theName = raw_input ("What is your name?? ")

Upvotes: 0

Views: 1950

Answers (2)

kdopen
kdopen

Reputation: 8215

As mentioned by others your code has a few problems.

First, if the theName contains anything other than digits, you will never enter the while loop, because isdigit() will return False.

Next, the order of your tests means that you will only reach the isalpha() test if the entered name contains something other than letters or digits.

However, it is also overly complex. Assuming your goal is to get the user to enter a name consisting only of letters (i.e. no spaces, digits, or special characters)

theName = "1" # preseed with invalid value
firstTime = True
while not theName.isalpha():
    if not firstTime:
        print "Your name should not contain anything other than letters"
    theName = raw_input("Please enter your name: ")
    firstTime = False

print "OK, great. Hi " + theName

This will repeatedly prompt until the user enters a valid name.

Upvotes: 0

dashiell
dashiell

Reputation: 812

theName = raw_input ("What is your name?? ")

while not theName.isalpha ():
    if theName.isdigit ():
        print "What kind of real name has just numbers in it?? Try again..."
    elif theName.isalnum ():
        print "What kind of name has any numbers in it?? Please try again..."
    theName = raw_input ("What is your name?? ")
print "Ok, great"

The while condition should tell you when to stop looping, that is, when the input isalpha. Then, because the while loop stops when the input is correct, you can move the logic for what to do in that case below the loop.

Looping on isdigit is problematic because the string abc123 doesn't meet that condition, so you break out of the loop even though the name doesn't meet your criteria.

Upvotes: 1

Related Questions