![]() matches an opening tag with any number of attributes. The regex matches an opening XML tag without any attributes. The regular expression \i \c * matches an XML name like xml:schema. They’re very useful for validating XML references and values in your XML schemas. You can use these four shorthands both inside and outside character classes using the bracket notation. Note that the \c shorthand syntax conflicts with the control character syntax used in many other regex flavors. \I and \C are the respective negated shorthands. \c matches any character that may occur after the first character in an XML name. \i matches any character that may be the first character of an XML name. ![]() XML Schema, XPath, and JGsoft V2 regular expressions support four more shorthands that aren’t supported by any other regular expression flavors. It matches a single hexadecimal digit just like. Ruby 1.9 and later have their own version of \h. Boost 1.42 and later support \v as a shorthand only outside character classes. To avoid confusion, the above paragraph uses \cK to represent the vertical tab.īoost supports \h starting with version 1.42. The vertical tab is also a vertical whitespace character. Java 8 and JGsoft V2 changed the meaning of this token anyway. Java 4 to 7 and JGsoft V1 did use \v to match only the vertical tab. Perl, PCRE, and PHP never supported this, so they were free to give \v a different meaning. In many other regex flavors, \v matches only the vertical tab character. Using \h instead of \s to match spaces and tabs makes sure your regex match doesn’t accidentally spill into the next line. If your flavor supports \h and \v then you should definitely use them instead of \s whenever you want to match only one type of whitespace. PHP does as of version 5.2.2, Java as of version 8, and the JGsoft engine as of version 2. PCRE also supports \h and \v starting with version 7.2. \h matches horizontal whitespace, which includes the tab and all characters in the “space separator” Unicode category. While support for \d, \s, and \w is quite universal, there are some regex flavors that support additional shorthand character classes. Because all digits are not whitespace, and all whitespace characters are not digits, matches any character digit, whitespace, or otherwise. The former, however, matches any character that is either not a digit, or is not whitespace. The latter matches any character that is neither a digit nor whitespace. īe careful when using the negated shorthands inside square brackets. \D is the same as, \W is short for and \S is the equivalent of. The above three shorthands also have negated versions. matches a hexadecimal digit, and is equivalent to if your flavor only matches ASCII characters with \d. When applied to 1 + 2 = 3, the former regex matches 2 (space two), while the latter matches 1 (one). matches a single character that is either whitespace or a digit. \s \d matches a whitespace character followed by a digit. Shorthand character classes can be used both inside and outside the square brackets. But JavaScript does match all Unicode whitespace with \s. In flavors that support Unicode, \s normally includes all characters from the Unicode “separator” category. Most flavors also include the vertical tab, with Perl (prior to version 5.18) and PCRE (prior to version 8.34) being notable exceptions. That is: \s matches a space, a tab, a carriage return, a line feed, or a form feed. In all flavors discussed in this tutorial, it includes. Again, which characters this actually includes, depends on the regex flavor. ![]() Again, Java, JavaScript, and PCRE match only ASCII characters with \w. XML Schema and XPath even include all symbols in \w. Connector punctuation other than the underscore and numeric symbols that aren’t digits may or may not be included. Letters and digits from alphabetic scripts and ideographs are generally included. There is a lot of inconsistency about which characters are actually included. In most flavors that support Unicode, \w includes many characters from other scripts. Notice the inclusion of the underscore and digits. These Unicode flavors match only ASCII digits with \d. Notable exceptions are Java, JavaScript, and PCRE. In most flavors that support Unicode, \d includes all digits from all scripts. Since certain character classes are used often, a series of shorthand character classes are available.
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