Answers for "regex documentation"

python re compile

import re
#	Compile a regular expression pattern into a regular expression object, which can be used for matching using its match(), search() and other methods, described below.

prog = re.compile(pattern)
result = prog.match(string)

#	is equivalent to

result = re.match(pattern, string)

regex

Let regex;
/* shorthand character classes */
regex = /d/; // matches any digit, short for [0-9]
regex = /D/; // matches non-digits, short for [^0-9]
regex = /S/; // matches non-white space character
regex = /s/; // matches any white space character
regex = /w/; // matches character, short for [a-zA-Z_0-9]
regex = /W/; // matches non-word character [^w]
regex = /b/; // Matches a word boundary where a word character is [a-zA-Z0-9_]
These meta characters boast a pre-defined meaning and make various typical patterns easier to use.
/* matching using quantifiers */
regex= /X./; // matches any character
regex= /X*/; // Matches zero or several repetitions of letter X, is short for {0,}
regex= /X+-/; // matches one or more repetitions of letter X, is short for {1,}
regex= /X?/; // finds no or exactly one letter X, is short for is short for {0,1}.
regex= // d{3}; // matches three digits. {} describes the order of the preceding liberal
regex= // d{1,4} ; // means d must occur at least once and at a maximum of four
A quantifies helps developers to define how often an element occurs.
/* character ranges */
regex = /[a-z]/; // matches all lowercase letters
regex = /[A-Z]/; // matches all uppercase letters
regex = /[e-l]/; // matches lowercase letters e to l (inclusive)
regex = /[F-P]/; // matches all uppercase letters F to P (inclusive)
regex = /[0-9]/; // matches all digits
regex = /[5-9]/; // matches any digit from 5 to 9 (inclusive)
regex = / [a-d1-7]/; // matches a letter between a and d and figures from 1 to 7, but not d1
regex = /[a-zA-Z]/; // matches all lowercase and uppercase letters
regex = /[^a-zA-Z]/; // matches non-letters
/* matching using anchors */
regex = / ^The/; // matches any string that starts with “The”
regex = / end$/; // matches a string that ends with end
regex = / ^The end$/; // exact string match starting with “The” and ending with “End”
/* escape characters */
regex = / a/; // match a bell or alarm
regex = / e/; // matches an escape
regex = / f/; // matches a form feed
regex = / n/; // matches a new line
regex = / Q…E/; // ingnores any special meanings in what is being matched
regex = / r/; // matches a carriage return
regex = / v/; // matches a vertical tab
It is critical to note that escape characters are case sensitive
/* matching using flags */
regex = / i/; // ignores the case in pattern ( upper and lower case allowed)
regex = / m/; // multi-line match
regex = / s/; // match new lines
regex = / x/; // allow spaces and comments
regex = / j/; // duplicate group names allowed
regex = / U/; // ungreedy match

re.match() python

import re

pattern = '^a...s$'
test_string = 'abyss'
result = re.match(pattern, test_string)

if result:
  print("Search successful.")
else:
  print("Search unsuccessful.")

re python3

import re
>>> m = re.search('(?<=abc)def', 'abcdef')
>>> m.group(0)
'def'

regex /

// replaces all / in a String with _
str = str.replace(///g,'_');

regex

Regular expression