正則表達(dá)式備忘單

這是開始使用正則表達(dá)式的快速備忘單。

• Python 中的正則表達(dá)式 
• JavaScript 中的正則表達(dá)式 
• PHP 中的正則表達(dá)式 
• Java 中的正則表達(dá)式 
• MySQL 中的正則表達(dá)式
• Vim 中的正則表達(dá)式
• Emacs 中的正則表達(dá)式 
• 在線正則表達(dá)式測(cè)試器 

• ^
• {
• +
• <
• [
• *
• )
• >
• .
• (
• |
• $
• \
• ?

轉(zhuǎn)義這些特殊字符 \

Lookaround 允許您在主模式之前 (lookbehind) 或之后 (lookahead) 匹配一個(gè)組，而不將其包含在結(jié)果中。

使用\搜索這些特殊字符：
[ \ ^ $ . | ? * + ( ) { }

當(dāng)備選方案重疊時(shí)，從長(zhǎng)到短排序

在[ ]總是逃避. \ ]有時(shí)^ - .

如果組后匹配失敗，解析器會(huì)嘗試每個(gè)替代方案。
可能導(dǎo)致災(zāi)難性的回溯。

盡可能使用非捕獲或原子組

“id”匹配，但\b在原子組之后失敗，解析器不會(huì)回溯到組以重試“身份”
如果替代品重疊，則從長(zhǎng)到短排序。

匹配 "Mr." 或者 "Ms."  如果單詞“her”在字符串后面

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

需要環(huán)視 ?if? 條件

導(dǎo)入正則表達(dá)式模塊

import re

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 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 QuickRef!
echo preg_replace($regex, "QuickRef", $str); 

$str = "Visit QuickRef";
$regex = "#quickref#i";

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

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

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

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])

還有更多的方法...

expr REGEXP pat 

例子

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]]])

例子

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]]])

例子

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])

例子

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]]]])

例子

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