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<regex> library in C++ STL

Last Updated : 04 Sep, 2018
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Main classes

These classes encapsulate a regular expression and the results of matching a regular expression within a target sequence of characters.

  • basic_regex: Regular expression object (class template)
  • sub_match: Identifies the sequence of characters matched by a sub-expression (class template)
  • match_results: Identifies one regular expression match, including all sub-expression matches (class template)


These functions are used to apply the regular expression encapsulated in a regex to a target sequence of characters.

  • regex_match: Attempts to match a regular expression to an entire character sequence (function template)
  • regex_search: Attempts to match a regular expression to any part of a character sequence. (function template)
  • regex_replace: Replaces occurrences of a regular expression with formatted replacement text. (function template)


The regex iterators are used to traverse the entire set of regular expression matches found within a sequence.

  • regex_iterator: Iterates through all regex matches within a character sequence. (class template)
  • regex_token_iterator: Iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template)


This class defines the type of objects thrown as exceptions to report errors from the regular expressions library.

  • regex_error: Reports errors generated by the regular expressions library. (class)


The regex traits class is used to encapsulate the localizable aspects of a regex.

  • regex_traits: Provides metainformation about a character type, required by the regex library. (class template)

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