Regex Cheat Sheet

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

import re

>>> 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(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']

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

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

>>> 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

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));

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 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 = "Here are apples and apPleS";
let regex = /apples/gi;

// Output: [ "apples", "apPleS" ]
console.log(text.match(regex));

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 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 = "Do you like aPPles?";
let regex = /apples/i;

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

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);

$str = "Visit Microsoft!";
$regex = "/microsoft/i";

// Output: Visit CheatSheets!
echo preg_replace($regex, "CheatSheets", $str);

$str = "Visit CheatSheets";
$regex = "#cheatsheets#i";

// Output: 1
echo preg_match($regex, $str);

$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]);
}

$arr = ["Jane", "jane", "Joan", "JANE"];
$regex = "/Jane/";

// Output: Jane
echo preg_grep($regex, $arr);

$str = "Jane\tKate\nLucy Marion";
$regex = "@\s@";

// Output: Array("Jane", "Kate", "Lucy", "Marion")
print_r(preg_split($regex, $str));

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

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

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

String regex = "[A-Z\n]{5}$";
String str = "I like APP\nLE";

Pattern p = Pattern.compile(regex, Pattern.MULTILINE);
Matcher m = p.matcher(str);

// Outputs: I like Apple!
System.out.println(m.replaceAll("pple!"));

String str = "She sells seashells by the Seashore";
String regex = "\\w*se\\w*";

Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
Matcher m = p.matcher(str);

List<String> matches = new ArrayList<>();
while (m.find()) {
    matches.add(m.group());
}

// Outputs: [sells, seashells, Seashore]
System.out.println(matches);

expr REGEXP pat

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

REGEXP_REPLACE(expr, pat, repl[, pos[, occurrence[, match_type]]])

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

REGEXP_SUBSTR(expr, pat[, pos[, occurrence[, match_type]]])

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

REGEXP_LIKE(expr, pat[, match_type])

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_INSTR(expr, pat[, pos[, occurrence[, return_option[, match_type]]]])

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