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sure! regular expressions (regex) are a powerful tool for matching patterns in strings. in python, the `re` module provides support for working with regular expressions. here’s a comprehensive tutorial on using regular expressions in python.

what are regular expressions?

regular expressions are sequences of characters that define a search pattern. they are commonly used for string searching, manipulation, and validation.

importing the `re` module

to work with regular expressions in python, you need to import the `re` module:



basic functions in the `re` module

1. **re.match()**: checks for a match only at the beginning of the string.
2. **re.search()**: scans through the string and looks for a location where the regex pattern produces a match.
3. **re.findall()**: returns a list of all matches of the pattern in the string.
4. **re.finditer()**: returns an iterator yielding match objects for all matches.
5. **re.sub()**: replaces occurrences of a pattern with a replacement string.
6. **re.split()**: splits the string by the occurrences of the pattern.

common patterns

`.`: matches any character except a newline.
`^`: matches the start of the string.
`$`: matches the end of the string.
`*`: matches zero or more repetitions of the preceding re.
`+`: matches one or more repetitions of the preceding re.
`?`: matches zero or one repetition of the preceding re.
`{m,n}`: matches from `m` to `n` repetitions of the preceding re.
`[]`: matches any single character within the brackets.
`|`: acts like a logical or.
`\`: escapes special characters.

example usage

#### 1. matching a pattern



#### 2. searching for a pattern



#### 3. finding all matches



#### 4. replacing text



#### 5. splitting a string



using groups

you can use parentheses to create groups in your regex patterns. this allows you to extract specific parts of the match.



flags

you can modify the behavior of the regex with flags:

`re.ignorecase ...

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