Super complete regular expressions

01 Regular expressions

• The role of regular expressions ： The best choice for matching special characters or characters with special matching principles .
• Regular expression's greedy ( greedy ) And not greedy ( Not greed ) Pattern ：
  （1） Greedy mode ： Regular expressions do maximum length matching , It's called greedy matching .
  （2） Non greedy model ： Just match the result , Less to match characters .
  （3） Under legal circumstances , Regular expressions will match as many as possible . But if you want regular to match as few characters as possible , Then you can put a question mark after the symbol that represents the number ?.（ for example ：{n,}? or *? or +? or ?? or {m,n}?）
• Recommend an easy-to-use regular expression testing tool ： Regular expression online test . There are also commonly used regular expressions ！

Metacharacters

Regular expression languages consist of two basic character types ： etymon （ normal ） Text characters and Metacharacters . Metacharacters give regular expressions processing power . Metacharacters are special characters that have special meaning in regular expressions , It can be used to specify its leading characters （ The character before the metacharacter ） The occurrence pattern in the target object .

A metacharacter is a character or group of characters that replace one or more characters . as follows ：

character	describe
\	Mark the next character as a special character 、 Or an original character 、 Or a Backward reference 、 Or an octal escape character .
^	Matches the start of the input string .
$	Matches the end of the input string .
*	Match previous subexpression zero or more times . Equivalent to {0,}.
+	Match previous subexpression one or more times . Equivalent to {1,}.
?	Match previous subexpression zero or once . Equivalent to {0,1}.
{n}	n Is a non negative integer . Matched definite n Time .
{n,}	n Is a non negative integer . Match at least n Time .
{n,m}	m and n All non negative integers , among n <= m. Least match n Times and at most m Time .
.	Match break （\n、\r） Any single character other than . Equivalent to [^\r\n]
\b	Matches a word boundary , That is, the position between the word and the space .
\B	Match non word boundaries .
\d	Matches a numeric character . Equivalent to [0-9].
\D	Matches a non-numeric character . Equivalent to [^0-9].
\s	Matches any whitespace characters , Including Spaces 、 tabs 、 Form-feed character, etc . Equivalent to [\f\n\r\t\v].
\S	Matches any non-whitespace characters . Equivalent to [^ \f\n\r\t\v].
\w	Match the letter 、 Numbers 、 Underline . Equivalent to [A-Za-z0-9_].
\W	Match nonletter 、 Numbers 、 Underline . Equivalent to [^A-Za-z0-9_].
\f	Match a page break . Equivalent to \x0c and \cL.
\n	Match a line break . Equivalent to \x0a and \cJ.
\r	Match a carriage return . Equivalent to \x0d and \cM.
\t	Match a tab . Equivalent to \x09 and \cI.
\v	Match a vertical tab . Equivalent to \x0b and \cK.
\xxx	Looking to 8 Hexadecimal number xxx Prescribed characters
\xdd	Looking to 6 Hexadecimal number dd Prescribed characters
\uxxxx	Looking to 16 Hexadecimal number xxxx Stipulated unicode character
\ Integers	backreferences . for example ：(a)\1/ matching aa;(\w)\1(\w)\2/ matching XXYY String of type

notes ： When it's time to ? Immediately following any other qualifier (*, +, ?, {n}, {n,}, {n,m}) In the back , Matching patterns are non greedy . The non greedy pattern matches as few strings as possible , The default greedy pattern matches as many strings as possible . for example , For strings “oooo”,‘o+?’ Will match a single “o”, and ‘o+’ Will match all ‘o’.

02 Check the expression of a number

• Numbers ：^[0-9]*$
• n Digit number ：^\d{n}$
• At least n Digit number ：^\d{n,}$
• m-n Digit number ：^\d{m,n}$
• Zero and non-zero digits ：^(0|[1-9][0-9]*)$
• A number with a maximum of two decimal places beginning with a nonzero ：^([1-9][0-9]*)+(\.[0-9]{1,2})?$
• belt 1-2 Positive or negative number of decimal places ：^(\-)?\d+(\.\d{1,2})$
• Positive numbers 、 negative 、 And decimal fraction ：^(\-|\+)?\d+(\.\d+)?$
• A positive real number with two decimal places ：^[0-9]+(\.[0-9]{2})?$
• Yes 1~3 Positive real number of decimal places ：^[0-9]+(\.[0-9]{1,3})?$
• Nonzero positive integer ：^[1-9]\d*$ or ^([1-9][0-9]*){1,3}$ or ^\+?[1-9][0-9]*$
• Nonzero negative integer ：^\-[1-9][]0-9"*$ or ^-[1-9]\d*$
• Non-negative integer ：^\d+$ or ^[1-9]\d*|0$
• Non positive integer ：^-[1-9]\d*|0$ or ^((-\d+)|(0+))$
• Nonnegative floating point number ：^\d+(\.\d+)?$ or ^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0$
• Non positive floating point number ：^((-\d+(\.\d+)?)|(0+(\.0+)?))$ or ^(-([1-9]\d*\.\d*|0\.\d*[1-9]\d*))|0?\.0+|0$
• Positive floating point ：^[1-9]\d*\.\d*|0\.\d*[1-9]\d*$ or ^(([0-9]+\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\.[0-9]+)|([0-9]*[1-9][0-9]*))$
• Negative floating point number ：^-([1-9]\d*\.\d*|0\.\d*[1-9]\d*)$ or ^(-(([0-9]+\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\.[0-9]+)|([0-9]*[1-9][0-9]*)))$
• Floating point numbers ：^(-?\d+)(\.\d+)?$ or ^-?([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0)$

03 Expression for check character

• Chinese characters ：^[\u4e00-\u9fa5]{0,}$
• English and numbers ：^[A-Za-z0-9]+$ or ^[A-Za-z0-9]{4,40}$
• The length is 3-20 All characters of ：^.{3,20}$
• from 26 A string of English letters ：^[A-Za-z]+$
• from 26 A string of uppercase letters ：^[A-Z]+$
• from 26 A string of lowercase letters ：^[a-z]+$
• By numbers and 26 A string of English letters ：^[A-Za-z0-9]+$
• By digital 、26 A string of English letters or underscores ：^\w+$ or ^\w{3,20}$
• chinese 、 english 、 Numbers include underscores ：^[\u4E00-\u9FA5A-Za-z0-9_]+$
• chinese 、 english 、 Number but excluding symbols such as underscores ：^[\u4E00-\u9FA5A-Za-z0-9]+$ or ^[\u4E00-\u9FA5A-Za-z0-9]- {2,20}$
• Can be entered with ^%&',;=?$\" Equal character ：[^%&',;=?$\x22]+
• Disable input containing ~ The characters of ：[^~\x22]+

04 Expression of special requirements

• Email Address ：^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$
• domain name ：[a-zA-Z0-9][-a-zA-Z0-9]{0,62}(\.[a-zA-Z0-9][-a-zA-Z0-9]{0,62})+\.?
• InternetURL：[a-zA-z]+://[^\s]* or ^http://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?$
• Phone number ：^(13[0-9]|14[5|7]|15[0|1|2|3|4|5|6|7|8|9]|18[0|1|2|3|5|6|7|8|9])\d{8}$
• Phone number (“XXX-XXXXXXX”、“XXXX-XXXXXXXX”、“XXX-XXXXXXX”、“XXX-XXXXXXXX”、"XXXXXXX" and "XXXXXXXX)：^(\(\d{3,4}-)|\d{3.4}-)?\d{7,8}$
• Domestic phone number (0511-4405222、021-87888822)：\d{3}-\d{8}|\d{4}-\d{7}
• Phone number regular expression （ Mobile number support ,3-4 Bit area code ,7-8 Bit live number ,1－4 Extension number ）: ((\d{11})|^((\d{7,8})|(\d{4}|\d{3})-(\d{7,8})|(\d{4}|\d{3})-(\d{7,8})-(\d{4}|\d{3}|\d{2}|\d{1})|(\d{7,8})-(\d{4}|\d{3}|\d{2}|\d{1}))$)
• ID number (15 position 、18 Digit number ), The last bit is the check bit , May be a number or character X：(^\d{15}$)|(^\d{18}$)|(^\d{17}(\d|X|x)$)
• Is the account number legal ( Beginning of letter , allow 5-16 byte , Allow alphanumeric underscores )：^[a-zA-Z][a-zA-Z0-9_]{4,15}$
• password ( Start with a letter , The length is in 6~18 Between , Can only contain letters 、 Numbers and underscores )：^[a-zA-Z]\w{5,17}$
• Strong password ( Must contain a combination of upper and lower case letters and numbers , Special characters cannot be used , The length is in 8-10 Between )：^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])[a-zA-Z0-9]{8,10}$
• Strong password ( Must contain a combination of upper and lower case letters and numbers , Special characters can be used , The length is in 8-10 Between )：^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,10}$
• Date format ：^\d{4}-\d{1,2}-\d{1,2}
• One year 12 Months (01～09 and 1～12)：^(0?[1-9]|1[0-2])$
• A month 31 God (01～09 and 1～31)：^((0?[1-9])|((1|2)[0-9])|30|31)$
• Input format of money ：

1. There are four forms of money we can accept :“10000.00” and “10,000.00”, And no “ branch ” Of “10000” and “10,000”：^[1-9][0-9]*$
2. This means that either of them can't 0 Number at the beginning , however , It also means a character "0" Not through , So we take the following form ：^(0|[1-9][0-9]*)$
3. One 0 Or one doesn't 0 Number at the beginning . We can also allow a minus sign at the beginning ：^(0|-?[1-9][0-9]*)$
4. This means a 0 Or a start that may be negative is not 0 The number of . Let users 0 The beginning is good. . Remove the minus sign as well , Because money can't be negative . What we're going to add here is the possible decimal part ：^[0-9]+(.[0-9]+)?$
5. It must be noted that , There should be at least one after the decimal point 1 digit , therefore "10." No way , however “10” and “10.2” Yes. ：^[0-9]+(.[0-9]{2})?$
6. In this way, we stipulate that there must be two decimal places after the decimal point , If you think it's too harsh , It can be like this ：^[0-9]+(.[0-9]{1,2})?$
7. This allows the user to write only one decimal place . Now it's time to think about commas in numbers , We can do this ：^[0-9]{1,3}(,[0-9]{3})*(.[0-9]{1,2})?$
8. 1 To 3 A digital , Follow any one comma +3 A digital , Comma as optional , Not necessarily ：^([0-9]+|[0-9]{1,3}(,[0-9]{3})*)(.[0-9]{1,2})?$

• xml file ：^([a-zA-Z]+-?)+[a-zA-Z0-9]+\\.[x|X][m|M][l|L]$
• Regular expression of Chinese characters ：[\u4e00-\u9fa5]
• Double byte character ：[^\x00-\xff]( Including Chinese characters , Can be used to calculate the length of a string ( A double byte character length meter 2,ASCII Character meter 1))
• Regular expression for blank lines ：\n\s*\r ( Can be used to delete blank lines )
• HTML Tagged regular expression ：<(\S*?)[^>]*>.*?|<.*? /> ( Regular expression of first and last whitespace characters ：^\s*|\s*$ or (^\s*)|(\s*$) ( Can be used to delete blank characters at the beginning and end of a line ( Including Spaces 、 tabs 、 Page breaks and so on ), Very useful expressions )
• China Post Code ：[1-9]\d{5}(?!\d) ( China Post code is 6 Digit number )
• IPv4 Address ：((2(5[0-5]|[0-4]\d))|[0-1]?\d{1,2})(\.((2(5[0-5]|[0-4]\d))|[0-1]?\d{1,2})){3}