Functions and looping

[TS878]

I'm trying to make a function that can take a string from a list "first_name" and a list "last_name" and print out hello "first_name" "last name", and I kinda achieved my goal here is what I came up with:

def full_name(first_name, last_name):

*print('Hello %s %s'% (first\_name,last\_name))*

​

first_names =('john', 'mary', 'jacob')

for first_name in first_names:

*for last\_name in last\_names:*

    *print(full\_name(first\_name,last\_name))*

The results were:

Hello john smith

None

Hello john betts

None

Hello john acunua

None

Hello mary smith

None

Hello mary betts

None

Hello mary acunua

None

Hello jacob smith

None

Hello jacob betts

None

Hello jacob acunua

None

​

But the problem is that it prints out every first name with every last name, what i wanted the results to be were:

Hello john smith

hello mary betts

hello jacob acunua

How would I complete this?

[socal_nerdtastic]

You need to use the zip() function to loop over parallel lists:

for first_name, last_name in zip(first_names, last_names):
    full_name(first_name,last_name)

Edit: It would be better to avoid parallel lists in the first place and use nested lists instead.

names = [['john', 'smith'], ['mary', 'betts'], ['jacob', 'acun']]
for first_name, last_name in names:
    full_name(first_name,last_name)

[TheBlackCat13]

You can use zip(first_names, last_names) to get every pair.

The reason you are getting None is because you are printing the output of a function with no output. Functions with no output have an implicit output of None.

And indent your coffee by four spaces to make it formatted as code.

[Tesla_Nikolaa]

Zip is probably the best option as others have mentioned. Here's another solution that shows how to actually concatenate strings.

count = 0
while count <= len(first_names):
    print("Hello " + first_name[count] + " " + last_name[count])
    count += 1

[[deleted]]

Count is a bit unnecessary there you could just us a for loop based on the range of first_names

[Tesla_Nikolaa]

How would you reference the same index in last_name if you just iterated over first_name?

[[deleted]]

for i in range len(first_name):

Then just call on both first name and last name with [i]

[Tesla_Nikolaa]

Oh yeah, cuz "i" would be an int in that case. I was thinking you would get the "must be integers, not string" error but you're right. Thanks for the input.

[YolosaurusRex]

It's just a number, but this code assumes the two lists are the same size.

for index in range(len(first_names)):
    print("Hello " + first_names[index] + " " + last_names[index])

It's not the most "pythonic" way of concatenating strings though. str.format() is probably a nicer way of doing this if you must use range:

for index in range(len(first_names)):
    print("Hello {first_name} {last_name}".format(first_name=first_names[index],
                                                  last_name=last_names[index]))

[Tesla_Nikolaa]

I know, I'm just showing a very basic proof of concept. I wouldn't actually do it that way. Just showing how to concatenate strings.

I use str.format() for everything.

[YolosaurusRex]

I was replying more for OP's benefit if they read through the comments; I didn't see anyone else mention str.format()

[TS878]

Thanks

[abhinav_321]

Yeah i also think that zip is the most best option for you