RegEX Cheat Sheet

REGEXP\_INSTR(expr, pat[, pos[, occurrence[, return\_option[, match\_type]]]]) 

#Examples

mysql> SELECT regexp_instr('aa aaa aaaa', 'a{3}'); 2 mysql> SELECT regexp_instr('abba', 'b{2}', 2); 2 mysql> SELECT regexp_instr('abbabba', 'b{2}', 1, 2); 5 mysql> SELECT regexp_instr('abbabba', 'b{2}', 1, 3, 1); 7 

REGEXP\_LIKE(expr, pat[, match\_type]) 

#Examples

mysql> SELECT regexp_like('aba', 'b+') 1 mysql> SELECT regexp_like('aba', 'b{2}') 0 mysql> # i: case-insensitive mysql> SELECT regexp_like('Abba', 'ABBA', 'i'); 1 mysql> # m: multi-line mysql> SELECT regexp_like('a\nb\nc', '^b$', 'm'); 1 

REGEXP\_SUBSTR(expr, pat[, pos[, occurrence[, match\_type]]]) 

#Examples

mysql> SELECT REGEXP_SUBSTR('abc def ghi', '[a-z]+'); abc mysql> SELECT REGEXP_SUBSTR('abc def ghi', '[a-z]+', 1, 3); ghi 

REGEXP\_REPLACE(expr, pat, repl[, pos[, occurrence[, match\_type]]]) 

#Examples

mysql> SELECT REGEXP_REPLACE('a b c', 'b', 'X'); a X c mysql> SELECT REGEXP_REPLACE('abc ghi', '[a-z]+', 'X', 1, 2); abc X 

expr REGEXP pat 

#Examples

mysql> SELECT 'abc' REGEXP '^[a-d]'; 1 mysql> SELECT name FROM cities WHERE name REGEXP '^A'; mysql> SELECT name FROM cities WHERE name NOT REGEXP '^A'; mysql> SELECT name FROM cities WHERE name REGEXP 'A|B|R'; mysql> SELECT 'a' REGEXP 'A', 'a' REGEXP BINARY 'A'; 1 0 

#Pattern

• Pattern compile(String regex [, int flags])
• boolean matches([String regex, ] CharSequence input)
• String[] split(String regex [, int limit])
• String quote(String s)

#Matcher

• int start([int group | String name])
• int end([int group | String name])
• boolean find([int start])
• String group([int group | String name])
• Matcher reset()

#String

• boolean matches(String regex)
• String replaceAll(String regex, String replacement)
• String[] split(String regex[, int limit]) There are more methods …

#First way

Pattern p = Pattern.compile(".s", Pattern.CASE_INSENSITIVE); Matcher m = p.matcher("aS"); boolean s1 = m.matches(); System.out.println(s1); // Outputs: true 

#Second way

boolean s2 = Pattern.compile("[0-9]+").matcher("123").matches(); System.out.println(s2); // Outputs: true 

#Third way

boolean s3 = Pattern.matches(".s", "XXXX"); System.out.println(s3); // Outputs: false 

$str = "Jane\tKate\nLucy Marion"; $regex = "@\s@"; // Output: Array("Jane", "Kate", "Lucy", "Marion") print\_r(preg\_split($regex, $str)); 

$arr = ["Jane", "jane", "Joan", "JANE"]; $regex = "/Jane/"; // Output: Jane echo preg\_grep($regex, $arr); 

$regex = "/[a-zA-Z]+ (\d+)/"; $input\_str = "June 24, August 13, and December 30"; if (preg\_match\_all($regex, $input\_str, $matches\_out)) { // Output: 2 echo count($matches\_out); // Output: 3 echo count($matches\_out[0]); // Output: Array("June 24", "August 13", "December 30") print\_r($matches\_out[0]); // Output: Array("24", "13", "30") print\_r($matches\_out[1]); } 

$str = "Visit QuickRef"; $regex = "#quickref#i"; // Output: 1 echo preg\_match($regex, $str); 

$str = "Visit Microsoft!"; $regex = "/microsoft/i"; // Output: Visit QuickRef! echo preg\_replace($regex, "QuickRef", $str); 

let regex = /apples/gi; let text = 'Here are apples and apPleS'; // Output: Here are mangoes and mangoes let result = text.replaceAll(regex, "mangoes"); console.log(result); 

let text = 'Do you like aPPles?'; let regex = /apples/i // Output: Do you like mangoes? let result = text.replace(regex, 'mangoes'); console.log(result); 

let regex = /t(e)(st(\d?))/g; let text = 'test1test2'; let array = [...text.matchAll(regex)]; // Output: ["test1", "e", "st1", "1"] console.log(array[0]); // Output: ["test2", "e", "st2", "2"] console.log(array[1]); 

let text = 'This 593 string will be brok294en at places where d1gits are.'; let regex = /\d+/g // Output: [ "This ", " string will be brok", "en at places where d", "gits are." ] console.log(text.split(regex)) 

let text = 'Here are apples and apPleS'; let regex = /apples/gi; // Output: [ "apples", "apPleS" ] console.log(text.match(regex)); 

let text = 'Do you like apples?'; let regex= /apples/; // Output: apples console.log(regex.exec(text)[0]); // Output: Do you like apples? console.log(regex.exec(text).input); 

let text = 'I like APPles very much'; let regexA = /apples/; let regexB = /apples/i; // Output: -1 console.log(text.search(regexA)); // Output: 7 console.log(text.search(regexB)); 

let textA = 'I like APPles very much'; let textB = 'I like APPles'; let regex = /apples$/i // Output: false console.log(regex.test(textA)); // Output: true console.log(regex.test(textB)); 

#re.search()

>>> sentence = 'This is a sample string' >>> bool(re.search(r'this', sentence, flags=re.I)) True >>> bool(re.search(r'xyz', sentence)) False 

#re.findall()

>>> re.findall(r'\bs?pare?\b', 'par spar apparent spare part pare') ['par', 'spar', 'spare', 'pare'] >>> re.findall(r'\b0\*[1-9]\d{2,}\b', '0501 035 154 12 26 98234') ['0501', '154', '98234'] 

#re.finditer()

>>> m_iter = re.finditer(r'[0-9]+', '45 349 651 593 4 204') >>> [m[0] for m in m_iter if int(m[0]) < 350] ['45', '349', '4', '204'] 

#re.split()

>>> re.split(r'\d+', 'Sample123string42with777numbers') ['Sample', 'string', 'with', 'numbers'] 

#re.sub()

>>> ip_lines = "catapults\nconcatenate\ncat" >>> print(re.sub(r'^', r'\* ', ip_lines, flags=re.M)) * catapults * concatenate * cat 

#re.compile()

>>> pet = re.compile(r'dog') >>> type(pet) <class '\_sre.SRE\_Pattern'> >>> bool(pet.search('They bought a dog')) True >>> bool(pet.search('A cat crossed their path')) False 

Match "Mr." or "Ms." if word "her" is later in string

M(?(?=.*?\bher\b)s|r)\. 

requires lookaround for IF condition

If alternatives overlap, order longer to shorter.

Can lead to catastrophic backtracking.

• ^
• {
• +
• <
• [
• *
• )
• >
• .
• (
• |
• $
• \
• ? Escape these special characters with \

This is a quick cheat sheet to getting started with regular expressions.

• Regex in Python (quickref.me)
• Regex in JavaScript (quickref.me)
• Regex in PHP (quickref.me)
• Regex in Java (quickref.me)
• Regex in MySQL (quickref.me)
• Regex in Vim (quickref.me)
• Regex in Emacs (quickref.me)
• Online regex tester (regex101.com)