Why does this code give me an error?

Question

I have this code:

import re
with open("text2.txt", "r") as f:
 content = f.readlines()
numbers = re.findall(r'\b\d{3}\b', content)
with open("text3.txt", "w") as f:
 f.write(str(numbers))

When run, it's supposed to find all of the three digit numbers, and print them to a new text file.

When I run it, I get this error:

Traceback (most recent call last):
 File "C:\Users\Zach\Desktop\test3.py", line 4, in <module>
 numbers = re.findall(r'\b\d{3}\b', content)
 File "C:\Panda3D-1.7.2\python\lib\re.py", line 177, in findall
 return _compile(pattern, flags).findall(string)
TypeError: expected string or buffer

What am I doing wrong?

• bereal: file.readlines() returns list of string, re.findall() requires a string.
• devnull: Moreover, you're specifying a list instead of a string.
• bereal: @devnull indentation is not a problem here: the file is read and then closed.

Answer 1

re.findall expects a string as its second argument, but the readlines method of a file object returns a list. Perhaps you meant to use the read method instead (which returns a string):

with open("text2.txt", "r") as f:
 content = f.read()