Regular (PHP and JS)

Warning: This is not an article detailing how to write regular rules.

One, regular expression

1. Time: hours 00-23
   '/(^[0-1][0-9]$)|(^2[0-3]$)/';
2. Time: minutes 00-59
   '/^[0-5][0-9]$/';
3. Mobile phone number: the beginning of 1, the second is 3 or 4 or 5 or 7 or 8, the last 9 digits end
   '/^1[3|4|5|7|8]\d{9}/';
4. mailbox
   '/^[\w-]{4,}@[\w]+\.(com|cn)$/';

Two, PHP regular method

1. preg_match() The return value matches 0 or 1, and the search stops after the first match.

   $str = 'abcdef';
   //用法一，根据返回值判断字符串是否符合正则
   echo preg_match('/abc/',$str); #输出1
   //用法二，传入第三个参数，取址生成一个数组。
   //一般来说，我们只关心匹配到的数组第0项,为正则匹配到的结果。
   //如果使用括号，会依次拆分匹配项。
   preg_match('/(bc)(de)/',$str,$match);
   print_r($match);
   //Array ( [0] => bcde [1] => bc [2] => de )
   

2. preg_match_all()Similar to the above, the return value matches 0 or n.

   $str = 'ABCdeABC';
   //用法一
   echo preg_match_all('/ABC/',$str);#输出2
   //用法二，match变成二维数组。
   preg_match_all('/ABC(de)?/',$str,$match);
   print_r($match);
   //[['ABCdeABC','ABC'],['de',null]]
   

3. preg_replace() Return the replaced string

   $str = 'ABCdeABC';
   echo preg_replace('/ABC/','abc',$str);# 输出abcdeabc
   

4. preg_grep() Return the matched array

   $arr1 = ['ABCdeABC','abc','ABC'];
   $arr2 = preg_grep('/ABC/',$arr1);
   print_r($arr2);
   //Array ( [0] => ABCdeABC [2] => ABC )
   

Three, JS regular writing

1. Grammatical directness/pattern/attributes

   var str = 'abc123de';
   /[a-z]/g; // 注意，
   

2. Syntax for creating RegExp objectsnew RegExp(pattern, attributes)

   var regexp = new RegExp(/[a-z]/,'g');
   

   Note 1: The regularity of JS does not need to be enclosed in single or double quotation marks.
   Note 2: Regarding attributes
   i, perform a case-insensitive matching.
   g Perform a global match (find all matches instead of stopping after the first match is found).
   m Perform multi-line matching.

Four, JS regular method

1. regexp.test() Retrieval, whether the string conforms to the regular expression, return true or false

   /abc/i.test('ABCdeABC'); //true
   

2. regexp.exec()Match, return if none null.

   var str = "ABCdeABC"; 
   var regexp = new RegExp("ABC","g");
   var result;
   
   while ((result = regexp.exec(str)) != null)  {
         
         
   	console.log(result,result.index,regexp.lastIndex);
   }
   

Five, the regularity in the JS string method

1. str.search() Search, return the position of the first substring that matches the regular, without returning -1.

   var str = 'ABCdeABC';
   str.search(/BC/);//返回1 
   //如果明确搜索什么，还是用indexOf('BC')吧...
   

2. str.match()Match, return the matched array, otherwise return null.

   str.match(/abc/ig);//返回 ['ABC','ABC']
   

3. str.replace()Replace, return the replaced string

   str.replace(/abc/i,"");//返回deabc
   str.replace(/abc/ig,"");//返回de
   //隐藏手机号中间四位
   '15388880131'.replace(/(\d{3})(\d{4})(\d{4})/,"$1****$3");
   //返回153****0131，这里$1,$2,$3分别代表3个()的匹配项。