Regex Flashcards
What import is needed to use regex?
import re
How does a basic regex in python looks like?
match = re.search(r’searchstring’,string)
Show an example of the following anchors?
- Beginning of a string
- End of a string
- Word boundary
re. search(‘^SearchString’,string)
re. search(‘SearchString$’,string)
re. search(‘\bSearchString\b’,string)
How to search for special characters?
re.search(‘\?’,string)
How to define the regex in a variable?
pattern = r'Yves' string1 = "Yves Sturzenegger" match1 = re.search(pattern, string1)
What are character classes for:
any lowercase letter
any uppercase letter
any letter
hexadecimal values
r’[a-z]’
r’[A-Z]’
r’[a-zA-Z]’
r’[a-fA-F0-9]’
Regex example to check if only one char was entered?
r’^[a-zA-Z]$’
Write a pattern that matches any word that begins with b, followed by a vowel, and ending with t.
\bb[aeiou]t\b
Match any digit or carat symbol
Match line that does not contain numbers
Match any line containing a digit
Match any line containing a minus, zero or nine
r’[0-9^]’
r’[^0-9]’
r’[0-9]’
r’[-09]
What are the special character classes for:
[0-9] (digits)
[\t\r\n] (whitespaces)
[A-Za-z0-9_]
\d
\s
\w
What are the special character classes for:
[^0-9] (digits)
[^\t\r\n] (whitespaces)
[^A-Za-z0-9_]
\D
\S
\W
Regex should check only one of the following words item0, item1….
^item\d$
Find any three character?
r’\b…\b’
Find any line that contains only one character?
r’^.$’
Match any word that contains three lowercase letters?
r’\b[a-z]{3}\b’
5 ‘a’ characters
5 or more ‘a’ characters
between 5 and 7 ‘a’ characters
between 3 and 5 lowercase characters
r’a{5}’
r’a{5,}’
r’a{5,7}’
r’[a-z]{3,5}’
What is the shorthand version of:
a{0,} - zero ore more
a{1,} - one or more
a{0,1} - zero or one
a*
a+
a?
Find any number, whether it’s a whole number or a decimal
r’\d+.?\d*’
Search for dog or cat or fish
r’dog|cat|fish’
Search for cat or bat?
r’cat|bat’
r’[cb]at’
Search for:
hack, crack, hacking, hacked, cracking, cracked
r’(hack|crack)(ing|ed)?’
Search for IP address?
r’(\d{1,3}.){3}\d{1,3}’
Search for credit card?
r’(\d{4} ){3}\d{4}’
How to match groups?
r’([A-Za-z]+), (0-9]+)
all = match.group(0)
all = match.group()
name = match.group(1)
number = match.group(2)
Replace occurrences of ‘H’ with ‘h’
text = re.sub(r’H’, r’h’, text)
What is the difference between re.search() and re.findall()
re. search: finds first occurrence
re. findall: finds all occurrences
