Special characters in regular expressions:
Character
Meaning: For a character, it is usually expressed as literal meaning that the next character is a special character and is not interpreted.
For example:/b/matches the character B, by adding a backslash in front of B, which is/b/, the character becomes a special character, indicating
Match the dividing line of a word.
Or:
For several characters, the usual description is special, which indicates that the characters immediately followed are not special, but should be interpreted literally.
For example: * is a special character that matches any character (including 0 characters); For example:/a*/means matching 0 or more aces.
To match the literal *, precede a with a backslash; For example:/a*/matches a *.
Character ^
Meaning: The character that represents the match must be at the front.
For example:/^a/does not match "an A," in a, but matches "an A." In the top of a.
Character $
Meaning: Similar to ^, matches the last character.
For example:/t$/does not match T in "Eater", but matches T in "eat".
Characters
Meaning: matches the preceding character 0 or n times.
For example:/bo*/matches B in "a Ghost booooed" in Boooo or "a bird warbled", but does not match "a goat g
Any characters in the runted ".
Character +
Meaning: Matches the character preceding the + sign 1 or n times. Equivalent to {1,}.
For example:/a+/matches A and "Caaaaaaandy" in "Candy". All a in the.
Character?
Meaning: match the preceding character 0 or 1 times.
For example:/e?le?/matches el in "Angel" and "angle." In the Le.
Character.
Meaning: (decimal point) matches all the individual characters except the line break.
For example:/.n/matches an and on of "Nay, an apple was on the tree" but does not match nay.
Character (x)
Meaning: Match x and record the matching value.
For example:/(foo)/Match and record "Foo bar." In the Foo. The matched substring can be in the result array of the vegetarian [1], ..., [n] Return
Back, or the property of the RegExp object, $ ..., $9 returns.
Character X|y
Meaning: match x or Y.
For example:/green|red/matches green apple and red apple. In the red.
Character {n}
Meaning: n Here is a positive integer. Matches the preceding n characters.
For example:/a{2}/does not match a in "candy," but matches all a in "Caandy," and "Caaandy." In front of the two
A.
Character {n,}
Meaning: n Here is a positive integer. Matches at least n preceding characters.
For example:/a{2,} does not match a in "Candy", but matches all A and "Caaaaaaandy" in "Caandy". All A In the
Character {n,m}
Meaning: Both N and m are positive integers. Matches at least N of the characters up to M preceding.
For example:/a{1,3}/does not match any of the characters in "Cndy", but matches "candy," in the first two in "A," "Caandy,"
A and "Caaaaaaandy" in front of the three A, note: even if "caaaaaaandy" There are many a, but only match the previous three
A is "AAA".
character [XYZ]
Meaning: A list of characters that matches any one of the characters listed. You can use hyphens-to indicate a range of characters.
For example: [ABCD] is the same as [a-c]. They match C in "brisket" in B and "ache".
character [^XYZ]
Meaning: A character complement, that is, it matches everything except the listed characters. You can use hyphens-to indicate a
The character range.
For example: [^ABC] and [^a-c] are equivalent, they first match R in "brisket" and "chop." In the H.
character [b]
Meaning: Match a space (do not confuse with B)
Character B
Meaning: Match the dividing line of a word, such as a space (not to be confused with [b])
For example:/bnw/matches the no,/wyb/match "possibly yesterday" in "Noonday". In the LY.
Character B
Meaning: Match the non-dividing line of a word
For example:/wbn/matches the on,/ybw/match "possibly yesterday" in "Noonday". In the Ye.
Character CX
Meaning: The x here is a control character. Matches the control character of a string.
For example:/cm/matches a control-m in a string.
Character D
Meaning: Match a number, equivalent to [0-9].
For example:/d/or/[0-9]/matches "B2 is the suite number." In the 2.
Character D
Meaning: matches any non-number, equivalent to [^0-9].
For example:/d/or/[^0-9]/matches "B2 is the suite number." In the B.
Character F
Meaning: Match a single form character
Character N
Meaning: Match a line break
Character R
Meaning: Match a carriage return character
Character S
Meaning: Match a single white space character, including spaces, tab,form feeds, line breaks, equivalent to [FNRTV].
For example:/sw*/matches "foo bar." Bar in the.
Character S
Meaning: matches a single character except white space, equivalent to [^ FNRTV].
For example:/s/w* matches "foo bar." In the Foo.
Character T
Meaning: Match a tab
Character V
Meaning: Match a head tab
Character W
Meaning: Matches all numbers and letters as well as underscores, equivalent to [a-za-z0-9_].
For example:/w/matches "Apple," in A, "$5.28," in 5 and "3D." In the 3.
Character W
Meaning: Matches other characters except numbers, letters, and underscores, equivalent to [^a-za-z0-9_].
For example:/w/or/[^ $A-za-z0-9_]/match "50%." % in the.
Character N
Meaning: n Here is a positive integer. Matches the value of N of the last substring of a regular expression (counting the left parenthesis).
For example:/apple (,) sorange1/matches "Apple, orange, cherry, peach." In the apple, Orange, below
There is a more complete example.
Note: If the number in the left parenthesis is smaller than the number specified by N, then N takes a line of octal escape as a description.
Characters Ooctal and Xhex
Meaning: The ooctal here is an octal escape value, while Xhex is a hexadecimal escape value that allows the embedding of ASCII code in a regular expression.
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