How to make RegEx in Python
What is a regular expression?
A regular expression is a sequence of symbols that identifies a set of strings. They are made with special characters and sequences. In Python, a regular expression can be used through the re module.
In this shot, we will learn how to make a simple regex.
Common special characters
-
.: matches any text except a newline. -
^: matches the start of the string. -
＄: matches end of the string (before a newline). -
*: matches zero or more patterns of a certain regex. -
+: matches one or more patterns of a certain regex. -
?: matches zero or one repetition of the previous regex. -
{x}: matches exactlyxcopies of the previous regex. It can be extended specifyingnrepetitions with{x, y}and with?. -
\: escapes special characters. -
[]: matches a set of characters. -
|: work asORbetween two regexes. -
(): matches whatever regex is inside it and can be extended with?.
Common special sequences
A special sequence is identified by a \. For example, we can use:
-
\A: matches the start of the string. -
\b: matches an empty string only if it’s not at the beginning of the string. -
\S: matches any character which is not an empty string.
How to use it
The re module also provides different methods to interact with strings, such as:
find()search()match()split()escape()
More information about regex can be found in the official documentation here.
Code
import rex = re.search("lo", "Hello educative!")print(x)# split at every spacex = re.split("\s", "Hello educative! 2345aa 204 hellow")print(x)