Namespaces
Variants
Views
Actions

std::match_results<BidirIt,Alloc>::operator[]

From cppreference.com
< cpp‎ | regex‎ | match results
 
 
Regular expressions library
Classes
(C++11)
Algorithms
Iterators
Exceptions
Traits
Constants
(C++11)
Regex Grammar
 
 
const_reference operator[]( size_type n ) const;
(since C++11)

If n > 0 and n < size(), returns a reference to the std::sub_match representing the part of the target sequence that was matched by the nth captured marked subexpression).

If n == 0, returns a reference to the std::sub_match representing the part of the target sequence matched by the entire matched regular expression.

if n >= size(), returns a reference to a std::sub_match representing an unmatched sub-expression (an empty subrange of the target sequence).

The behavior is undefined unless ready() == true.

Contents

[edit] Parameters

n - integral number specifying which match to return

[edit] Return value

Reference to the std::sub_match representing the specified matched subrange within the target sequence.

[edit] Example

#include <iostream>
#include <regex>
#include <string>
 
int main()
{
    std::string target("baaaby");
    std::smatch sm;
 
    std::regex re1("a(a)*b");
    std::regex_search(target, sm, re1);
    std::cout << "entire match: " << sm[0] << '\n'
              << "submatch #1: " << sm[1] << '\n';
 
    std::regex re2("a(a*)b");
    std::regex_search(target, sm, re2);
    std::cout << "entire match: " << sm[0] << '\n'
              << "submatch #1: " << sm[1] << '\n';
}

Output:

entire match: aaab
submatch #1: a
entire match: aaab
submatch #1: aa

[edit] See also

returns the sequence of characters for the particular sub-match
(public member function) [edit]