| Localization library | |||||||||||||||||||||||||
| Regular expressions library(C++11) | |||||||||||||||||||||||||
| Formatting library(C++20) | |||||||||||||||||||||||||
| Null-terminated sequence utilities | |||||||||||||||||||||||||
| Byte strings | |||||||||||||||||||||||||
| Multibyte strings | |||||||||||||||||||||||||
| Wide strings | |||||||||||||||||||||||||
| Primitive numeric conversions | |||||||||||||||||||||||||
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| Text encoding identifications | |||||||||||||||||||||||||
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| Classes | ||||
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sub_match (C++11) | ||||
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| Algorithms | ||||
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| Iterators | ||||
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| Exceptions | ||||
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| Traits | ||||
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| Constants | ||||
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| Regex Grammar | ||||
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| Member functions | ||||
| Non-member functions | ||||
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) | ||||
Defined in header <regex> | ||
template<class BidirIt> class sub_match; | (since C++11) | |
The class templatestd::sub_match is used by the regular expression engine to denote sequences of characters matched by marked sub-expressions.A match is a[begin, end) pair within the target range matched by the regular expression, but with additional observer functions to enhance code clarity.
Only the default constructor is publicly accessible. Instances ofstd::sub_match are normally constructed and populated as a part of astd::match_results container during the processing of one of the regex algorithms.
The member functions return defined default values unless thematched member istrue.
std::sub_match inherits fromstd::pair<BidirIt, BidirIt>, although it cannot be treated as astd::pair object because member functions such as assignment will not work as expected.
Contents |
-BidirIt must meet the requirements ofLegacyBidirectionalIterator. |
Several specializations for common character sequence types are provided:
Defined in header <regex> | |
| Type | Definition |
std::csub_match | std::sub_match<constchar*> |
std::wcsub_match | std::sub_match<constwchar_t*> |
std::ssub_match | std::sub_match<std::string::const_iterator> |
std::wssub_match | std::sub_match<std::wstring::const_iterator> |
| Type | Definition |
iterator | BidirIt |
value_type | std::iterator_traits<BidirIt>::value_type |
difference_type | std::iterator_traits<BidirIt>::difference_type |
string_type | std::basic_string<value_type> |
| Member | Description |
bool matched | whether this match was successful (public member object) |
BidirIt first | start of the match sequence (public member object) |
BidirIt second | one-past-the-end of the match sequence (public member object) |
| constructs the match object (public member function)[edit] | |
Observers | |
| returns the length of the match (if any) (public member function)[edit] | |
| converts to the underlying string type (public member function)[edit] | |
| compares matched subsequence (if any) (public member function)[edit] | |
Modifiers | |
| swaps the contents (public member function)[edit] | |
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | compares asub_match with anothersub_match, a string, or a character(function template)[edit] |
| outputs the matched character subsequence (function template)[edit] |
#include <cassert>#include <iostream>#include <regex>#include <string> int main(){std::string sentence{"Friday the thirteenth."};conststd::regex re{"([A-z]+) ([a-z]+) ([a-z]+)"};std::smatch words;std::regex_search(sentence, words, re);std::cout<<std::boolalpha;for(constauto& m: words){assert(m.matched);std::cout<<"m: ["<< m<<"], m.length(): "<< m.length()<<", ""*m.first: '"<<*m.first<<"', ""*m.second: '"<<*m.second<<"'\n";}}
Output:
m: [Friday the thirteenth], m.length(): 21, *m.first: 'F', *m.second: '.'m: [Friday], m.length(): 6, *m.first: 'F', *m.second: ' 'm: [the], m.length(): 3, *m.first: 't', *m.second: ' 'm: [thirteenth], m.length(): 10, *m.first: 't', *m.second: '.'
(C++11) | iterates through the specified sub-expressions within all regex matches in a given string or through unmatched substrings (class template)[edit] |
