Regular expression learning and common regular validation rules (including username, password, phone number, URL, etc.)

Regular expression base syntax

1.1 match different types of characters

Character class	Matched characters
\d	Matches a numeric character. equivalent to [0-9].
\d	Matches a non-numeric character. equivalent to [^0-9].
\w	Matches any word character that includes an underscore. Equivalent to ' [a-za-z0-9_] '.
\w	Matches any non-word character. Equivalent to ' [^a-za-z0-9_] '.
\s	Matches any whitespace character, including spaces, tabs, page breaks, and so on. equivalent to [\f\n\r\t\v].
\s	Matches any non-whitespace character. equivalent to [^ \f\n\r\t\v].
. (Point number)	Any one character
[...]	Any one of the characters in parentheses
[^ ...]	Any character in a non-parenthesis

1.2 Positioning control characters

^	The subsequent pattern must be at the beginning of the string, and if it is multiple lines at the beginning of any line C # needs to set the multiline flag
$	The preceding pattern must be at the end of a line, and if it is multiple lines, at the end of any line
\a	The preceding pattern must be at the beginning of the string, and multiline flags are ignored
\z	The preceding pattern must be at the end of the string, and multiline flags are ignored
\z	The preceding pattern must be at the end of the string or before the line break
\b	Matches the beginning of a word character, a word character that is one of [a-za-z0-9]
\b	Matches a non-word boundary position, not the beginning of a word

1.3 Specify repeating characters

N	matches the preceding character n times
{N,}	Matches the preceding character at least n times
{N,m}	Match the preceding characters n to M times
?	Match the preceding character 0 or 1 times
+	Match the preceding character at least 1 times
*	Match the preceding character at least 0 times

1.4 Special Control class

|	Specifies the character substitution, where the position can be either an expression on either side of the |

1.5 special character escape sequences

\\	Match "\"
\.	Match "."
\*	Match "*"
\(	Match "("
\)	Match ")"
\?	Match "? ”
\+	Match "+"
\|	Match "|"
\{	Match "{"
\}	Match "}"
\^	Match "^"
\$	Match "$"
\ n	Match line break
\ r	Match carriage return
\ t	Match Tab key
\v	Match vertical Tabs
\f	Match a page break
\nnn	Matches the ASCII character specified by a three-bit octal number, such as \103 match C
\xnn	Matches an ASCII character specified by a two-bit 16 binary, such as \x43 match C
\unnnn	Matches the Unicode character specified by a 4-bit 16 binary number
\cv	Match a control character (such as copy CTRL + C)

CommonRegular validation rules

1. Detecting user Names

Requirements: 5 to 17 characters are preceded by a letter, a combination of numbers and English symbols

Regular expression:/^[a-za-z][[email protected]~!?] {4,16}$/

2. Password detection

Requirements: 8 to 17 characters are combined by letters, numbers, and English symbols

Regular expression:/^[[email protected]~!?] {8,17}$/

3. Detect mobile phone number

Requirements: Accurate matching of all mobile phone numbers, including mobile, unicom, telecommunications

Regular expression:/^ (((13[4-9)) |147| ( 15[0-27-9]) |178| (18[2-47-8])) [0-9] {8}) | ((170[356]) [0-9]{7}]
| (((13[0-2)) |145| (15[56]) | (18[56]) |17[16]) [0-9]{8}) | ((170[4789]) [0-9]{7}]
| ((133|153| (18[019]) |177) [0-9]{8}) | ((170[0-2]) [0-9]{7}] $/

4. Match URL URLs

Requirements: http//And www. But there is no

For example: www.baidu.com, baidu.com, http://www.baidu.com, https://i.cnblogs.com/EditPosts.aspx?opt=1

Regular expression:/^ (((https|http|ftp|): \ /\/)? (www\.)? ([\w_\-\.] {0,61}) + (\.\w{2,10}) + (\/)? [\[email protected]&=#\-\.\/] {0,}) | (#)$/

Regular expression learning and common regular validation rules (including username, password, phone number, URL, etc.)