Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Basics (2015) Python Data Types String Formatting

Kevin Ryu
Kevin Ryu
1,286 Points
Posted by Kevin Ryu
Kevin Ryu
1,286 Points

Why does this code not work to assign the "name" to the subject string with the use of .format?

Please see code below. The goal is to have correctly use the .format to add name to subject placeholder. I don't understand why it does not work.

strings.py 
name = 'Kevin'
subject = "Treehouse loves {} "
subject.format(name)

1 Answer

Jon Mirow
Jon Mirow
9,864 Points

Hi there!

Ah I've made this mistake before too, don't worry. It's because the sting method format returns the value, but doesn't by itself assign it to the variable. You have to specify you want it to do that for you, because strings are immutable (they can't be changed), whilst it looks like you're just updating the string, what's actually happening is you're taking the value out of the variable, changing it and then overwriting the old value in the variable. So

bob = "Bob {}"
bob.format("Geldoff")

won't change it, but

bob = "Bob {}"
bob = bob.format("Geldoff")

will.

Hope it helps!