Xbl: Xbl moved page Regex to Regular Expressions without leaving a redirect

2022-03-16T10:35:07Z

Xbl moved page Regex to Regular Expressions without leaving a redirect

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Xbl: Created page with "== Regular Expressions == {| class="wikitable" |- ! Metacharacter ! Description |- valign="top" !`\` |Escape character. |- |- valign="top" !`?` |Matches the preceding element zero or one time. For example, `ab?c` matches only "ac" or "abc". |- !`+` |Matches the preceding element one or more times. For example, `ab+c` matches "abc", "abbc", "abbbc", and so on, but not "ac". |- !`|` |The ch..."

2022-02-25T12:24:58Z

Created page with "== Regular Expressions == {| class="wikitable" |- ! Metacharacter ! Description |- valign="top" !<code>\</code> |Escape character. |- |- valign="top" !<code>?</code> |Matches the preceding element zero or one time. For example, <code>ab?c</code> matches only "ac" or "abc". |- !<code>+</code> |Matches the preceding element one or more times. For example, <code>ab+c</code> matches "abc", "abbc", "abbbc", and so on, but not "ac". |- !<code><nowiki>|</nowiki></code> |The ch..."

New page

== Regular Expressions ==

{| class="wikitable"
|-
! Metacharacter
! Description
|- valign="top"
!<code>\</code>
|Escape character.
|-
|- valign="top"
!<code>?</code>
|Matches the preceding element zero or one time. For example, <code>ab?c</code> matches only "ac" or "abc".
|-
!<code>+</code>
|Matches the preceding element one or more times. For example, <code>ab+c</code> matches "abc", "abbc", "abbbc", and so on, but not "ac".
|-
!<code><nowiki>|</nowiki></code>
|The choice (also known as alternation or set union) operator matches either the expression before or the expression after the operator. For example, <code><nowiki>abc|def</nowiki></code> matches "abc" or "def".
|-
|- valign="top"
!<code>*</code>
|Matches the preceding element zero or more times. For example, <code>ab*c</code> matches "ac", "abc", "abbbc", etc. <code>[xyz]*</code> matches "", "x", "y", "z", "zx", "zyx", "xyzzy", and so on. <code>(ab)*</code> matches "", "ab", "abab", "ababab", and so on.
|-
|- valign="top"
!<code>^</code>
|Matches the starting position within the string. In line-based tools, it matches the starting position of any line.
|-
|- valign="top"
!<code>.</code>
|Matches any single character (many applications exclude [[newline]]s, and exactly which characters are considered newlines is flavor-, character-encoding-, and platform-specific, but it is safe to assume that the line feed character is included). Within POSIX bracket expressions, the dot character matches a literal dot. For example, <code>a.c</code> matches "abc", etc., but <code>[a.c]</code> matches only "a", ".", or "c".
|- valign="top"
!<code>[ ]</code>
|A bracket expression. Matches a single character that is contained within the brackets. For example, <code>[abc]</code> matches "a", "b", or "c". <code>[a-z]</code> specifies a range which matches any lowercase letter from "a" to "z". These forms can be mixed: <code>[abcx-z]</code> matches "a", "b", "c", "x", "y", or "z", as does <code>[a-cx-z]</code>.
The <code>-</code> character is treated as a literal character if it is the last or the first (after the <code>^</code>, if present) character within the brackets: <code>[abc-]</code>, <code>[-abc]</code>. Note that backslash escapes are not allowed. The <code>]</code> character can be included in a bracket expression if it is the first (after the <code>^</code>) character: <code>[]abc]</code>.
|- valign="top"
!<code>[^ ]</code>
|Matches a single character that is not contained within the brackets. For example, <code>[^abc]</code> matches any character other than "a", "b", or "c". <code>[^a-z]</code> matches any single character that is not a lowercase letter from "a" to "z". Likewise, literal characters and ranges can be mixed.
|- valign="top"
!<code>$</code>
|Matches the ending position of the string or the position just before a string-ending newline. In line-based tools, it matches the ending position of any line.
|- valign="top"
!<code>( )</code>
|Defines a marked subexpression. The string matched within the parentheses can be recalled later (see the next entry, <code>\''n''</code>). A marked subexpression is also called a block or capturing group. '''BRE mode requires <code></code>'''.
|- valign="top"
!<code>\''n''</code>
|Matches what the ''n''th marked subexpression matched, where ''n'' is a digit from 1 to 9. This construct is vaguely defined in the POSIX.2 standard. Some tools allow referencing more than nine capturing groups. Also known as a backreference. '''backreferences are only supported in BRE mode'''
|- valign="top"
!<code>{''m'',''n''}</code>
|Matches the preceding element at least ''m'' and not more than ''n'' times. For example, <code>a{3,5}</code> matches only "aaa", "aaaa", and "aaaaa". This is not found in a few older instances of regexes. '''BRE mode requires <code>\{''m'',''n''\}</code>'''.

|}

'''Examples:'''
* <code>[hc]?at</code> matches "at", "hat", and "cat".
* <code>[hc]*at</code> matches "at", "hat", "cat", "hhat", "chat", "hcat", "cchchat", and so on.
* <code>[hc]+at</code> matches "hat", "cat", "hhat", "chat", "hcat", "cchchat", and so on, but not "at".
* <code>cat|dog</code> matches "cat" or "dog".
* <code>.at</code> matches any three-character string ending with "at", including "hat", "cat", "bat", "4at", "#at" and " at" (starting with a space).
* <code>[hc]at</code> matches "hat" and "cat".
* <code>[^b]at</code> matches all strings matched by <code>.at</code> except "bat".
* <code>[^hc]at</code> matches all strings matched by <code>.at</code> other than "hat" and "cat".
* <code>^[hc]at</code> matches "hat" and "cat", but only at the beginning of the string or line.
* <code>[hc]at$</code> matches "hat" and "cat", but only at the end of the string or line.
* <code>\[.\]</code> matches any single character surrounded by "[" and "]" since the brackets are escaped, for example: "[a]", "[b]", "[7]", "[@]", "[]]", and "[ ]" (bracket space bracket).
* <code>s.*</code> matches s followed by zero or more characters, for example: "s", "saw", "seed", "s3w96.7", and "s6#h%(>>>m n mQ".

Regular Expressions - Revision history

Xbl: Xbl moved page Regex to Regular Expressions without leaving a redirect