| Localization library | |||||||||||||||||||||||||
| Regular expressions library(C++11) | |||||||||||||||||||||||||
| Formatting library(C++20) | |||||||||||||||||||||||||
| Null-terminated sequence utilities | |||||||||||||||||||||||||
| Byte strings | |||||||||||||||||||||||||
| Multibyte strings | |||||||||||||||||||||||||
| Wide strings | |||||||||||||||||||||||||
| Primitive numeric conversions | |||||||||||||||||||||||||
| |||||||||||||||||||||||||
| Text encoding identifications | |||||||||||||||||||||||||
| |||||||||||||||||||||||||
| Classes | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
| Algorithms | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
| Iterators | ||||
(C++11) | ||||
(C++11) | ||||
| Exceptions | ||||
(C++11) | ||||
| Traits | ||||
(C++11) | ||||
| Constants | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
| Regex Grammar | ||||
(C++11) |
The regular expressions library provides a class that representsregular expressions, which are a kind of mini-language used to perform pattern matching within strings. Almost all operations with regexes can be characterized by operating on several of the following objects:
Contents |
Patterns and replacement strings support the following regular expression grammars:
Some grammar variations (such as case-insensitive matching) are also avaliable, seethis page for details.
These classes encapsulate a regular expression and the results of matching a regular expression within a target sequence of characters.
(C++11) | regular expression object (class template)[edit] |
(C++11) | identifies the sequence of characters matched by a sub-expression (class template)[edit] |
(C++11) | identifies one regular expression match, including all sub-expression matches (class template)[edit] |
These functions are used to apply the regular expression encapsulated in a regex to a target sequence of characters.
(C++11) | attempts to match a regular expression to an entire character sequence (function template)[edit] |
(C++11) | attempts to match a regular expression to any part of a character sequence (function template)[edit] |
(C++11) | replaces occurrences of a regular expression with formatted replacement text (function template)[edit] |
The regex iterators are used to traverse the entire set of regular expression matches found within a sequence.
(C++11) | iterates through all regex matches within a character sequence (class template)[edit] |
(C++11) | iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template)[edit] |
This class defines the type of objects thrown as exceptions to report errors from the regular expressions library.
(C++11) | reports errors generated by the regular expressions library (class)[edit] |
The regex traits class is used to encapsulate the localizable aspects of a regex.
(C++11) | provides metainformation about a character type, required by the regex library (class template)[edit] |
Defined in namespace std::regex_constants | |
(C++11) | general options controlling regex behavior (typedef)[edit] |
(C++11) | options specific to matching (typedef)[edit] |
(C++11) | describes different types of matching errors (typedef)[edit] |
#include <iostream>#include <iterator>#include <regex>#include <string> int main(){std::string s="Some people, when confronted with a problem, think ""\"I know, I'll use regular expressions.\" ""Now they have two problems."; std::regex self_regex("REGULAR EXPRESSIONS",std::regex_constants::ECMAScript|std::regex_constants::icase);if(std::regex_search(s, self_regex))std::cout<<"Text contains the phrase 'regular expressions'\n"; std::regex word_regex("(\\w+)");auto words_begin=std::sregex_iterator(s.begin(), s.end(), word_regex);auto words_end=std::sregex_iterator(); std::cout<<"Found "<<std::distance(words_begin, words_end)<<" words\n"; constint N=6;std::cout<<"Words longer than "<< N<<" characters:\n";for(std::sregex_iterator i= words_begin; i!= words_end;++i){std::smatch match=*i;std::string match_str= match.str();if(match_str.size()> N)std::cout<<" "<< match_str<<'\n';} std::regex long_word_regex("(\\w{7,})");std::string new_s=std::regex_replace(s, long_word_regex,"[$&]");std::cout<< new_s<<'\n';}
Output:
Text contains the phrase 'regular expressions'Found 20 wordsWords longer than 6 characters: confronted problem regular expressions problemsSome people, when [confronted] with a [problem], think "I know, I'll use [regular] [expressions]." Now they have two [problems].
