![]() ![]() matches all the target sequences "a", "B", "b", and "c". An identity escape of the form \k, which matches the character k in the target sequence.Ī matches the target sequence "a" but doesn't match the target sequences "B", "b", or "c".Anchor $ matches the end of the target sequence.Ī capture group of the form ( subexpression), or \( subexpression\) in basic and grep, which matches the sequence of characters in the target sequence that is matched by the pattern between the delimiters. Anchor ^ matches the beginning of the target sequence. Adds the collation element elt to the set defined by expr.Īn anchor. ![]() Adds the collating elements that are equivalent to elt to the set defined by expr.Ī collating symbol of the form. Adds the characters in the named class to the set defined by expr.Īn equivalence class of the form. Adds the characters that are represented by values in the closed range to the set defined by expr.Ī character class of the form. Adds the character to the set defined by expr.Ī character range of the form ch1-ch2. The expression expr can contain any combination of the following:Īn individual character. ElementĪn ordinary character that matches the same character in the target sequence.Ī wildcard character '.' that matches any character in the target sequence except a newline.Ī bracket expression of the form, which matches a character or a collation element in the target sequence that is also in the set defined by the expression expr, or of the form, which matches a character or a collation element in the target sequence that isn't in the set defined by the expression expr. If only flags are specified, ECMAScript is assumed as the grammar. Zero or more flags may be combined with the grammar to specify the regular expression engine behavior. collate: Use locale-sensitive collation sequences (for example, ranges of the form ).optimize: Make matching faster, at the possible expense of greater construction time.nosubs: Ignore marked matches (that is, expressions in parentheses) no substitutions are stored.egrep: This is extended, but it also allows newline characters to separate alternations.īy default, if no grammar is specified, ECMAScript is assumed.grep: This is basic, but it also allows newline ( \n) characters to separate alternations.awk: This is extended, but it has more escapes for non-printing characters.extended: The POSIX extended regular expressions or ERE.basic: The POSIX basic regular expressions or BRE.ECMAScript: This is closest to the grammar used by JavaScript and the.These regular expression grammars are defined in std::regex_constants: The regular expression grammar to use is by specified by the use of one of the std::regex_constants::syntax_option_type enumeration values. This topic discusses the grammar variations available when using regular expressions. The C++ standard library supports multiple regular expression grammars. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |