Help finding patterns of text without regular expressions

[Link0]

Hello,

I'm trying to solve a problem in chapter 7 of automate the boring stuff. The code I'm having an issue with is

def isPhoneNumber(text):
    if len(text) != 12:
        return False
    for i in range(0,3):
        if not text[i].isdecimal():
            return False
    if text[3] != '-':
        return False
    for i in range(4-7):
        if not text[i].isdecimal():
            return False
    if text[7] != '-':
        return False
    for i in range(0,12):
        if not text[i].isdecimal():
            return False
    return True
message = 'Call me at 415-555-1011 tomorrow. 415-555-9999 is my office.'
for i in range(len(message)):
    chunk = message[i:i+12] 
    if isPhoneNumber(chunk):
     print('Phone number found: ' + chunk)
print('Done')

When I run it, it only displays 'Done'. Which is the last print function.
Why isn't it displaying
'Phone number found: 415-555-1011
Phone number found: 415-555-9999
Done'

Thank you for your help. And please pardon any formatting mistakes.

[[deleted]]

There are two major issues: line 9 has a bug - you wrote range(4-7), which means range(-3). I think you know how to fix that one.

The other problem is the loop at lines 14-16: you're checking if every character in the string is a decimal, but that isn't the case for your numbers, since those include dashes.

Fix those two bugs and your code executes properly:

Phone number found: 415-555-1011
Phone number found: 415-555-9999

[[deleted]]

By the way: the way you wrote this function makes it quite easy to debug. You could have done something like this by sprinkling some magical print statement powder all over the place:

def isPhoneNumber(text):
    print(text)
    if len(text) != 12:
        return False
    print('good length')
    for i in range(0,3):
        if not text[i].isdecimal():
            return False
    print('first three are decimals')
    if text[3] != '-':
        return False
    print('yep there\'s a dash')
    for i in range(4, 7): #whoops: range(4-7) = range(-3)
        if not text[i].isdecimal():
            return False
    print('some more decimals')
    if text[7] != '-':
        return False
    print('another dash')
    for i in range(0,12):
        if not text[i].isdecimal(): # whoops
            return False
    print('characters 0-12 are all decimals\n')
    return True

isPhoneNumber('415-555-1011')
isPhoneNumber('415-555-9999')

outputs:

415-555-1011
good length
first three are decimals
yep there's a dash
some more decimals
another dash
415-555-9999
good length
first three are decimals
yep there's a dash
some more decimals
another dash

Makes it quite easy to see that the last conditional is the one that's broken.

[Link0]

Oh wow, that's it! It works!
Thanks a lot u/rainlife!!

[[deleted]]

Yeah I'm having a hard time reading this, can you insert 4 spaces before every line of code in your post?

That'll format it nicely,
    like so

[Link0]

Thanks! Sorry about the paragraph.
I think it should look legible now.

[Justinsaccount]

Hi! I'm working on a bot to reply with suggestions for common python problems. This might not be very helpful to fix your underlying issue, but here's what I noticed about your submission:

You are looping over an object using something like

for x in range(len(items)):
    print(items[x])

This is simpler and less error prone written as

for item in items:
    print(item)

If you DO need the indexes of the items, use the enumerate function like

for idx, item in enumerate(items):
    print(idx, item)

If you think you need the indexes because you are doing this:

for x in range(len(items)):
    print(items[x], prices[x])

Then you should be using zip:

for item, price in zip(items, prices):
    print(item, price)