String processing issue using a Python intro text

Question

What's wrong with this bit of Python? Entering the names does not work.

def main():
    print("This program generates computer usernames.\n")

    # get user's first and last names
    first = input("Please enter your first name (all lowercase): ")
    last = input("Please enter your last name (all lowercase): ")

    # concatenate first initial with 7 chars of the last name
    uname = first[0] + last[:7]

    # output the username
    print("Your username is:", uname)

main()

Now, running the program results in this -- no idea what it's all about.

cd '/Users/ek/Desktop/' && '/usr/bin/pythonw'                     '/Users/ek/Desktop/fun.py'  && echo Exit status: $? && exit 1
EKs-Mac-mini:~ ek$ cd '/Users/ek/Desktop/' && '/usr/bin/pythonw'  '/Users/ek/Desktop/fun.py'  && echo Exit status: $? && exit 1


This program generates computer usernames.

Please enter your first name (all lowercase): Bob


Traceback (most recent call last):
File "/Users/ek/Desktop/fun.py", line 14, in <module>
main()
File "/Users/ek/Desktop/fun.py", line 5, in main
first = input("Please enter your first name (all lowercase): ")
File "<string>", line 1, in <module>
NameError: name 'Bob' is not defined
EKs-Mac-mini:Desktop ek$ 

Answer 1

In your code, change input (which works in Python 3) to raw_input (which works in Python 2) and see what happens.

And to confirm which Python version you're using, run this Terminal command: python --version

Answer 2

Instead of changing input to raw_input so your script will work in Python 2, you could add a shebang line so the Terminal shell will run your script in Python 3.

A shebang line tells the shell (1) that the file is a shell script, (2) which Python interpreter to use, and (3) where to find that interpreter (the file path).

Then you should just be able to run $ fun.py in Terminal. You shouldn't need to specify $ python3 fun.py.

---

Two ways to write the shebang line.

1) Put this line at the top of your fun.py file:

#! /usr/bin/env python3

That is the recommended way to write the shebang line. It works in UNIX-like operating systems (including Linux, Mac OS X, etc.)

2) Or, specify the complete absolute path to the location where Python 3 is installed. In your case:

#! /Library/Frameworks/Python.framework/Versions/3.5/bin/python3

If you don't know the absolute path, find it using the Terminal command $ which python3.

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P.S. As an alternative, changing the default version of Python on your system from Python 2 to Python 3 might also work. But it has other bad consequences so don't do it.