Metacharacters and metacharacters

Metacharacters and metacharacters

　　

 

What are the metacharacters of a regular expression?

Character Description
\ Mark the next character as a special character, an original character, or a backward reference, or an octal escape character. For example, "n" matches the character "n ". "\ N" matches a line break. The sequence "\" matches "\", and "\ (" matches "(".
^ Matches the start position of the input string. If the Multiline attribute of the RegExp object is set, ^ matches the position after "\ n" or "\ r.
$ Matches the end position of the input string. If the Multiline attribute of the RegExp object is set, $ also matches the position before "\ n" or "\ r.
* Matches the previous subexpression zero or multiple times. For example, zo * can match "z" and "zoo ". * Is equivalent to {0 ,}.
+ Match the previous subexpression once or multiple times. For example, "zo +" can match "zo" and "zoo", but cannot match "z ". + Is equivalent to {1 ,}.
? Match the previous subexpression zero or once. For example, "do (es )?" It can match "do" in "do" or "does ".? It is equivalent to {0, 1 }.
{N} n is a non-negative integer. Match n times. For example, "o {2}" cannot match "o" in "Bob", but can match two o in "food.
{N,} n is a non-negative integer. Match at least n times. For example, "o {2,}" cannot match "o" in "Bob", but can match all o in "foooood. "O {1,}" is equivalent to "o + ". "O {0,}" is equivalent to "o *".
Both {n, m} m and n are non-negative integers, where n <= m. Match at least n times and at most m times. For example, "o {1, 3}" matches the first three o in "fooooood. "O {0, 1}" is equivalent to "o ?". Note that there must be no space between a comma and two numbers.
? When this character is followed by any other delimiter (*, + ,?, The matching mode after {n}, {n ,}, {n, m}) is not greedy. The non-Greedy mode matches as few searched strings as possible, while the default greedy mode matches as many searched strings as possible. For example, for strings "oooo", "o + ?" A single "o" will be matched, while "o +" will match all "o ".
. Match any single character except "\ n. To match any character including "\ n", use a pattern like "[. \ n.
(Pattern) matches pattern and obtains this match. The obtained match can be obtained from the generated Matches set. The SubMatches set is used in VBScript, and $0… is used in JScript... $9 attribute. To match the parentheses, use "\ (" or "\)".
(? : Pattern) matches pattern but does not get the matching result. That is to say, this is a non-get match and is not stored for future use. This is useful when you use the "(|)" character to combine all parts of a pattern. For example, "industr (? : Y | ies) "is a simpler expression than" industry | industrial.
(? = Pattern) Forward pre-query: matches the search string at the beginning of any string that matches pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example (? = 95 | 98 | NT | 2000) "can match" Windows "in" Windows2000 ", but cannot match" Windows "in" Windows3.1 ". Pre-query does not consume characters, that is, after a match occurs, the next matching search starts immediately after the last match, instead of starting after the pre-query characters.
(?! Pattern) negative pre-query: matches the search string at the beginning of any string that does not match pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example, "Windows (?! 95 | 98 | NT | 2 ...... remaining full text>

What are the metacharacters of a regular expression?

Character Description
\ Mark the next character as a special character, an original character, or a backward reference, or an octal escape character. For example, "n" matches the character "n ". "\ N" matches a line break. The sequence "\" matches "\", and "\ (" matches "(".
^ Matches the start position of the input string. If the Multiline attribute of the RegExp object is set, ^ matches the position after "\ n" or "\ r.
$ Matches the end position of the input string. If the Multiline attribute of the RegExp object is set, $ also matches the position before "\ n" or "\ r.
* Matches the previous subexpression zero or multiple times. For example, zo * can match "z" and "zoo ". * Is equivalent to {0 ,}.
+ Match the previous subexpression once or multiple times. For example, "zo +" can match "zo" and "zoo", but cannot match "z ". + Is equivalent to {1 ,}.
? Match the previous subexpression zero or once. For example, "do (es )?" It can match "do" in "do" or "does ".? It is equivalent to {0, 1 }.
{N} n is a non-negative integer. Match n times. For example, "o {2}" cannot match "o" in "Bob", but can match two o in "food.
{N,} n is a non-negative integer. Match at least n times. For example, "o {2,}" cannot match "o" in "Bob", but can match all o in "foooood. "O {1,}" is equivalent to "o + ". "O {0,}" is equivalent to "o *".
Both {n, m} m and n are non-negative integers, where n <= m. Match at least n times and at most m times. For example, "o {1, 3}" matches the first three o in "fooooood. "O {0, 1}" is equivalent to "o ?". Note that there must be no space between a comma and two numbers.
? When this character is followed by any other delimiter (*, + ,?, The matching mode after {n}, {n ,}, {n, m}) is not greedy. The non-Greedy mode matches as few searched strings as possible, while the default greedy mode matches as many searched strings as possible. For example, for strings "oooo", "o + ?" A single "o" will be matched, while "o +" will match all "o ".
. Match any single character except "\ n. To match any character including "\ n", use a pattern like "[. \ n.
(Pattern) matches pattern and obtains this match. The obtained match can be obtained from the generated Matches set. The SubMatches set is used in VBScript, and $0… is used in JScript... $9 attribute. To match the parentheses, use "\ (" or "\)".
(? : Pattern) matches pattern but does not get the matching result. That is to say, this is a non-get match and is not stored for future use. This is useful when you use the "(|)" character to combine all parts of a pattern. For example, "industr (? : Y | ies) "is a simpler expression than" industry | industrial.
(? = Pattern) Forward pre-query: matches the search string at the beginning of any string that matches pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example (? = 95 | 98 | NT | 2000) "can match" Windows "in" Windows2000 ", but cannot match" Windows "in" Windows3.1 ". Pre-query does not consume characters, that is, after a match occurs, the next matching search starts immediately after the last match, instead of starting after the pre-query characters.
(?! Pattern) negative pre-query: matches the search string at the beginning of any string that does not match pattern. This is a non-get match, that is, the match does not need to be obtained for future use. For example, "Windows (?! 95 | 98 | NT | 2 ...... remaining full text>