• \w – Word character. That’s any letters, numbers, and the underscore character.
• \W – Anything but word characters.
• \s – Whitespaces.
• \S – Anything but whitespaces.
• \d – Numbers from 0 to 9
• \D – Anything but numbers.
• \b – Boundaries of words, defined by white space or the edges of the string.
• \B – Anything but boundaries.
• \w{3} – 3 word characters.
• \w{,3} – 0 – 3 word characters.
• \w{3,} – 3 or more word characters. No upper limit.
• \w{3, 5} – 3 – 5 word characters in a row.
• \w? – 0 or 1 word characters.
• \w* – 0 or more word characters.
• \w+ – 1 or more word characters. Must occur at least once!

import re

names_file = open("names.txt", encoding="utf-8")
data = names_file.read()
names_file.close()

# Search for phone numbers with the following form: (555) 555-5555 
print(re.search(r'\(\d\d\d\) \d\d\d-\d\d\d\d', data))

# Search for phone numbers: (555) 555-5555, 555-555-5555, 555 555-5555
print(re.findall(r'\(?\d{3}\)?-?\s?\d{3}-\d{4}', data))

# Search for last names with or without first names, such as: 'Bashar, Ghadanfar'
print(re.findall(r'\w*, \w+', data))

.findall( )
Finds all non-overlapping occurrences of the pattern in the text.

Exercise

Write a function named first_number that takes a string as an argument. The function should search, with a regular expression, the first number in the string and return the match object.

Then, write a function named numbers() that takes two arguments: a count as an integer and a string. Return an re.search for exactly count numbers in the string.

import re


def first_number(my_str):
    return re.search(r'\d', my_str)

def numbers(integer, string):
    result = re.search(r'\d'*integer, string)
    return result