std::sub_match::operator string_type, std::sub_match::str

From cppreference.com
< cpplrm; | regexlrm; | sub match
operator string_type() const;
(1)
string_type str() const;
(2)

Converts to an object of the underlying std::basic_string type.

The first version is an implicit conversion, the second one is explicit.

Parameters

(none)

Return value

Returns the matched character sequence as an object of the underlying std::basic_string type. If the matched member is false then the empty string is returned.

Complexity

Linear in the length of the underlying character sequence.

Example

#include <iostream>
#include <regex>
#include <string>
int main()
{
  std::ssub_match sm;
  std::string s = sm;  // implicit conversion
  std::cout << s.length() << '\n';
}

Output:

0