The meaning of some regular expressions

Regular expressions

1. Meaning of regular expressions

\d matches a numeric character,/\d/=/[0-9]/

\d matches a non-numeric character,/\d/=/[^0-9]/

\s matches a white space character, including \n,\r,\f,\t,\v , etc.

\s matches a non-whitespace character equal to /[^\n\f\r\t\v]/

\w matches a character that can make up a word, including underscores

\w matches a character that cannot be composed of words, equal to [^a-za-z0-9].

\ t matches a tab

\ n matches a line break

\ r matches a carriage return character

\ As a turn, the character usually after "\" is not interpreted as the original meaning, as \* represents an * number

^ matches the beginning of an input or a line,/^a/ matches "an A", and does not match "an A"

$ matches the end of an input or a line,/a$/ matches "an A", and does not match "an A"

* match the preceding metacharacters 0 or more times,/ba*/ will match B,ba,baa,baaa

+ match Front metacharacters 1 or more times,/ba+/ will match Ba,baa,baaa

? Match Front metacharacters 0 Times or 1 Times, /ba?/ will match B,ba

{n} exact match n times

{N,} Match N Times above

{N,m} Match n-m Times

. any character other than a line break , equivalent to [^\n]

X|y match x or y

[XYZ] Character Set (character Set) to match any of the one by one characters in this set ( or meta-character )

[^XYZ] does not match any one of the characters in this collection

[\b] match a backspace

2, using the syntax of the regular table above , You can describe the two-digit /\ d \ d/, the four-digit number described as /\d \ d \ d \ d/

3. Example

/\d{2, 4}/matches numbers between 2 and 4 .

/\W{3} \d?/matches three single character and an arbitrary number .

/\s+java\s+/matches the string "Java", and it can have one or more spaces before and after it .

4, commonly used regular expressions ( Some regular expressions are not very accurate, when using the self-modification can be )

1.match The regular expression of email address: \w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *

2. Regular expressionmatching url url :[a-za-z]+://[^\s]*

3. Match domestic phone number: \d{3}-\d{8}|\d{4}-\d{7}

\D{3}-\D{8}|\D{4}-\D{7}

Commentary: Match forms such as 0511-4405222 or 021-87888822

4. Matching ID:\d{15}|\d{18}

5. Match IP address:\d+\.\d+\.\d+\.\d+

6, match a specific number:
^[1-9]\d*$　 　 //match positive integers
^-[1-9]\d*$　 //match negative integers
^-? [1-9]\d*$　　 //Match integer
^[1-9]\d*|0$　 //matches a non-negative integer (positive integer+ 0)
^-[1-9]\d*|0$　　 //match a non-positive integer (negative integer+ 0)
^[1-9]\d*\.\d*|0\.\d*[1-9]\d*$　　 //match Positive floating point number
^-([1-9]\d*\.\d*|0\.\d*[1-9]\d*) $　 //match negative floating-point numbers
^-? ([1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0) $　 //matching floating-point numbers
^[1-9]\d*\.\d*|0\.\d*[1-9]\d*|0?\.0+|0$　　 //matching nonnegative floating-point numbers (positive floating-point numbers )+ 0)
^ (-([1-9]\d*\.\d*|0\.\d*[1-9]\d*)) |0?\.0+|0$　　//matching non-positive floating-point numbers (negative floating-point numbers )+ 0)
Commentary: useful when dealing with large amounts of data, with particular attention to remediation when applied

7. Match a specific string:
^[a-za-z]+$//Match a string consisting of 26 English letters
^[a-z]+$//matches a string consisting of 26 uppercase letters
^[a-z]+$//matches a string consisting of 26 letters in lowercase
^[a-za-z0-9]+$//matches a string consisting of a number and 26 English letters
^\w+$//matches a string consisting of a number, 26 letters, or underscores

To verify the Chinese regular expression:

/^ ([\u4e00-\u9fa5]| [\ufe30-\uffa0]) *$/

Whether the checksum is all made up of numbers
var patrn=/^[0-9]{1,20}$/

Check login name: Only 5-20 entries begin with a letter, can be numbered, "_", "." The string
var patrn=/^[a-za-z]{1} ([a-za-z0-9]|[. _]) {4,19}$/;

Verify user name: Only 1-30 strings beginning with a letter can be entered
var patrn=/^[a-za-z]{1,30}$/;

Check password: Only 6-20 letters, numbers, underscores can be entered
var patrn=/^ (\w) {6,20}$/;

Check the ordinary telephone, fax number: Can "+" start, in addition to the number, can contain "-"
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? (\d) {1,12}) +$/;
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? ((\d) | []) {1,12}) +$/;

Check mobile phone Number: Must start with a number, except the number, can contain "-"
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? ((\d) | []) {1,12}) +$/;

Verifying ZIP Codes
var patrn=/^[a-za-z0-9]{3,12}$/;

Verifying search Keywords
var patrn=/^[^ ' [email protected]#$%^&* () +=|\\\][\]\{\}:; ' \,.<>/?] {1} [^ ' [email protected]$%^& () +=|\\\] [\]\{\}:;‘ \,.<>?] {0,19}$/;
var patrn=/^[0-9.] {1,20}$/;

Regular expressions
^\\d+$//nonnegative integers (positive integers + 0)
^[0-9]*[1-9][0-9]*$//Positive integer
^ ((-\\d+) | (0+)) $//Non-positive integer (negative integer + 0)
^-[0-9]*[1-9][0-9]*$//Negative integer
^-?\\d+$//Integer
^\\d+ (\\.\\d+)? $//non-negative floating-point number (positive floating-point number + 0)
^ ([0-9]+\\. [0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*\\. [0-9]+) | ([0-9]*[1-9][0-9]*)) $//Positive floating-point number
^ ((-\\d+ (\\.\\d+)?) | (0+ (\\.0+)?)) $//non-positive floating-point number (negative floating-point number + 0)
^ (-([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
^ (-?\\d+) (\\.\\d+)? $//floating-point number
^[a-za-z]+$//A string consisting of 26 English letters
^[a-z]+$//A string consisting of 26 uppercase letters in English
^[a-z]+$//String consisting of 26 English letters in lowercase
^[a-za-z0-9]+$//String consisting of a number and 26 English letters
^\\w+$//String consisting of numbers, 26 English letters or underscores
^[\\w-]+ (\\.[ \\w-]+) *@[\\w-]+ (\\.[ \\w-]+) +$//email Address
^[a-za-z]+://(\\w+ (-\\w+) *) (\ \. ( \\w+ (-\\w+) *) * (\\?\\s*)? $//url
^[a-za-z0-9_]*$ JS Regular expression

Ghost posted in [2008-01-17 23:17]

Whether the checksum is all made up of numbers
var patrn=/^[0-9]{1,20}$/

Check login name: Only 5-20 entries begin with a letter, can be numbered, "_", "." The string
var patrn=/^[a-za-z]{1} ([a-za-z0-9]|[. _]) {4,19}$/;

Verify user name: Only 1-30 strings beginning with a letter can be entered
var patrn=/^[a-za-z]{1,30}$/;

Check password: Only 6-20 letters, numbers, underscores can be entered
var patrn=/^ (\w) {6,20}$/;

Check the ordinary telephone, fax number: Can "+" start, in addition to the number, can contain "-"
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? (\d) {1,12}) +$/;
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? ((\d) | []) {1,12}) +$/;

Check mobile phone Number: Must start with a number, except the number, can contain "-"
var patrn=/^[+]{0,1} (\d) {1,3}[]? ([-]? ((\d) | []) {1,12}) +$/;

Verifying ZIP Codes
var patrn=/^[a-za-z0-9]{3,12}$/;

Verifying search Keywords
var patrn=/^[^ ' [email protected]#$%^&* () +=|\\\][\]\{\}:; ' \,.<>/?] {1} [^ ' [email protected]$%^& () +=|\\\] [\]\{\}:;‘ \,.<>?] {0,19}$/;
var patrn=/^[0-9.] {1,20}$/;

Regular expressions
^\\d+$//nonnegative integers (positive integers + 0)
^[0-9]*[1-9][0-9]*$//Positive integer
^ ((-\\d+) | (0+)) $//Non-positive integer (negative integer + 0)
^-[0-9]*[1-9][0-9]*$//Negative integer
^-?\\d+$//Integer
^\\d+ (\\.\\d+)? $//non-negative floating-point number (positive floating-point number + 0)
^ ([0-9]+\\. [0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*\\. [0-9]+) | ([0-9]*[1-9][0-9]*)) $//Positive floating-point number
^ ((-\\d+ (\\.\\d+)?) | (0+ (\\.0+)?)) $//non-positive floating-point number (negative floating-point number + 0)
^ (-([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
^ (-?\\d+) (\\.\\d+)? $//floating-point number
^[a-za-z]+$//A string consisting of 26 English letters
^[a-z]+$//A string consisting of 26 uppercase letters in English
^[a-z]+$//String consisting of 26 English letters in lowercase
^[a-za-z0-9]+$//String consisting of a number and 26 English letters
^\\w+$//String consisting of numbers, 26 English letters or underscores
^[\\w-]+ (\\.[ \\w-]+) *@[\\w-]+ (\\.[ \\w-]+) +$//email Address
^[a-za-z]+://(\\w+ (-\\w+) *) (\ \. ( \\w+ (-\\w+) *) * (\\?\\s*)? $//url
^[a-za-z0-9_]*$

The meaning of some regular expressions