std::match_results::str

From cppreference.com
string_type str( size_type n = 0 ) const;
(since C++11)

Returns a string representing the indicated sub-match.

If n == 0, a string representing entire matched expression is returned.

If n > 0 && n < size(), a string representing nth sub-match is returned.

if n >= size(), a string representing the unmatched match is returned.

The call is equivalent to string_type((*this)[n]);

Contents

[edit] Parameters

n - integral number specifying which match to return

[edit] Return value

Returns a string representing the specified match or sub match.

[edit] Example

#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.str(1) << '\n';
}

Output:

aaa

[edit] See also

returns specified sub-match
(public member function)