C++ In a Nutshell

Name

pair class template — Represents a pair of related objects

Synopsis

template <typename T1, typename T2>
struct pair {
  typedef T1 first_type;
  typedef T2 second_type;
  T1 first;
  T2 second;
  pair(  );
  pair(const T1& x, const T2& y);
  template<typename U, typename V> pair(const pair<U, V> &p);
};

The pair class template represents a pair of related objects, in which the relationship is defined by the programmer. The most common use of pairs is by the map class template, which stores pairs of keys and associated objects.

The Boost project has a generalization of pair, called tuple. See Appendix B for information about Boost.

The pair constructors are straightforward:

pair ( )

Initializes first as T1( ) and second as T2( )

pair (const T1& x, const T2& y)

Initializes first with x and second with y

template<typename U, typename V> pair (const pair<U, V> &p)

Initializes first with p.first and second with p.second, performing implicit conversions as needed

See Also

make_pair function template