std::match_results::match_results

From cppreference.com
explicit match_results( const Allocator& a = Allocator() );
(1) (since C++11)
match_results( const match_results& rhs );
(2) (since C++11)
match_results( match_results&& rhs );
(3) (since C++11)
1) Default-constructor. Constructs a match result with no established result state (ready() != true).
2) Copy-constructor. Constructs a match result with a copy of rhs.
3) Move-constructor. Constructs a match result with the contents of rhs using move semantics. rhs is in valid, but unspecified state after the call.

[edit] Parameters

a - allocator to use for all memory allocations of this container
rhs - another match_result to use as source to initialize the match_result with

[edit] Exceptions

1-2) (none)
3)
noexcept specification:  
noexcept
  (since C++11)