Python re https://www.w3schools.com/
re
A RegEx, or Regular Expression, is a sequence of characters that forms a search pattern.
RegEx can be used to check if a string contains the specified search pattern.
Metacharacters are characters with a special meaning
| Character | Description | Example | Try it |
|---|---|---|---|
| [] | A set of characters | "[a-m]" | |
| \ | Signals a special sequence (can also be used to escape special characters) | "\d" | |
| . | Any character (except newline character) | "he..o" | |
| ^ | Starts with | "^hello" | |
| $ | Ends with | "world$" | |
| * | Zero or more occurrences | "aix*" | |
| + | One or more occurrences | "aix+" | |
| {} | Exactly the specified number of occurrences | "al{2}" | |
| | | Either or | "falls|stays" | |
| () | Capture and group |
A special sequence is a \ followed by one of the characters in the list below, and has a special meaning:
| Character | Description | Example | Try it |
|---|---|---|---|
| \A | Returns a match if the specified characters are at the beginning of the string | "\AThe" | |
| \b | Returns a match where the specified characters are at the beginning or at the end of a word (the "r" in the beginning is making sure that the string is being treated as a "raw string") | r"\bain" r"ain\b" | |
| \B | Returns a match where the specified characters are present, but NOT at the beginning (or at the end) of a word (the "r" in the beginning is making sure that the string is being treated as a "raw string") | r"\Bain" r"ain\B" | |
| \d | Returns a match where the string contains digits (numbers from 0-9) | "\d" | |
| \D | Returns a match where the string DOES NOT contain digits | "\D" | |
| \s | Returns a match where the string contains a white space character | "\s" | |
| \S | Returns a match where the string DOES NOT contain a white space character | "\S" | |
| \w | Returns a match where the string contains any word characters (characters from a to Z, digits from 0-9, and the underscore _ character) | "\w" | |
| \W | Returns a match where the string DOES NOT contain any word characters | "\W" | |
| \Z | Returns a match if the specified characters are at the end of the string | "Spain\Z" |
Sets
A set is a set of characters inside a pair of square brackets [] with a special meaning:
| Set | Description | Try it |
|---|---|---|
| [arn] | Returns a match where one of the specified characters (a, r, or n) are present | |
| [a-n] | Returns a match for any lower case character, alphabetically between a and n | |
| [^arn] | Returns a match for any character EXCEPT a, r, and n | |
| [0123] | Returns a match where any of the specified digits (0, 1, 2, or 3) are present | |
| [0-9] | Returns a match for any digit between 0 and 9 | |
| [0-5][0-9] | Returns a match for any two-digit numbers from 00 and 59 | |
| [a-zA-Z] | Returns a match for any character alphabetically between a and z, lower case OR upper case | |
| [+] | In sets, +, *, ., |, (), $,{} has no special meaning, so [+] means: return a match for any + character in the string |
import re
txt = "8 times before 11:45 AM"
#Check if the string has any characters from a to z lower case, and A to Z upper case:
x = re.findall("[a-zA-Z]", txt)
print(x)
if x:
print("Yes, there is at least one match!")
else:
print("No match")
Python RegEx
Reviewed by Uthid
on
พฤศจิกายน 24, 2563
Rating:
ไม่มีความคิดเห็น: