How do I use regular expressions to count the number of digits in python?

Answer 1

If you need to do it with regex:

import re

#number of words in a string
print(len(re.compile(r'\w+?\b').findall('your string goes here')))

# number of digits in a string
print(len(re.compile(r'\d').findall('your string goes here')))

Answer 2

Better question: Why?

You can easily do it without re, for example:

sum(s.isdigit() for s in your_str)

When you're confident the string only contains digits, you can just use len(your_str).

Answer 3

You can transform a string into a list of words and just count them.

len(your_string.split())

Answer 4

What of the regular expression for counting the number of words in a string?