std::match_results::size

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Regular expressions library

Classes

basic_regex (C++11)

sub_match (C++11)

match_results (C++11)

Algorithms

regex_match (C++11)

regex_search (C++11)

regex_replace (C++11)

Iterators

regex_iterator (C++11)

regex_token_iterator (C++11)

Exceptions

regex_error (C++11)

Traits

regex_traits (C++11)

Constants

syntax_option_type (C++11)

match_flag_type (C++11)

error_type (C++11)

 

std::match_results

Member functions

match_results::match_results

match_results::~match_results

match_results::operator=

match_results::get_allocator

State

match_results::ready

Element access

match_results::size

match_results::max_size

match_results::empty

match_results::length

match_results::position

match_results::str

match_results::operator_at

match_results::prefix

match_results::suffix

Iterators

match_results::begin match_results::cbegin

match_results::end match_results::cend

Format

match_results::format

Modifiers

match_results::swap

 

size_type size() const;		(since C++11)

Returns the number of submatches, i.e. std::distance(begin(), end()).

Parameters

(none)

Return value

The number of submatches

Exceptions

noexcept specification:  

noexcept

  (since C++11)

Complexity

Constant

Example

run this code

#include <iostream>
#include <regex>
#include <string>
 
int main()
{
    std::regex re("a(a)*b");
    std::string target("aaab");
    std::smatch sm;
 
    std::regex_match(target, sm, re);
    std::cout << sm.size() << '\n';
}

Output:

2