EASY Python Mistake!!

Here’s a Python mistake that’s very easy to make

Let’s say we have a list of domain names and we want to cycle through them and remove the www. at the beginning of each one.

links = [
      "www.amazon.com",
      "www.wikipedia.org",
      "www.reddit.com",
]

One way you might think to do this is to say

for link and links:
  print(link.lstrip("www."))

lstrip() essentially strips www. characters from the left side of the string

The problem is when we run this you’ll see that the w in www.wikipedia.org is gone

It’s because the input for lstrip() is actually a list of characters to remove.

It’s not looking to remove the substring www. so we could say w. and it would do the same thing.

It’s looking for all the W’s and . from the left side and removing them until it hits a character that’s not on this list.

Instead, we should use the removeprefix() method with an input of www.

for link and links:
  print(link.removeprefix("www."))

This method actually looks for the first instance of this substring from the left side and removes it