pair

Library:  General utilities

Does not inherit

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• Description
• Interface
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• Constructors
• Destructor
• Nonmember Operators
• Nonmember Functions
• See Also
• Standards Conformance

Members

first_type

pair()

second_type

~pair()

Non-Members

make_pair() operator!=()

operator>() operator>=()

operator<() operator<=()

operator==()

A template utility class for pairs of values that may be of different types

#include <utility>

namespace std {
  template <class T1, class T2>
  struct pair;
}

The pair class is a template for encapsulating pairs of values that may be of different types.

namespace std {

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

  template <class T1, class T2>
  bool operator==(const pair<T1, T2>&,
                  const pair T1, T2>&);

  template <class T1, class T2>
  bool operator!=(const pair<T1, T2>&,
                  const pair T1, T2>&);

  template <class T1, class T2>
  bool operator<(const pair<T1, T2>&,
                 const pair T1, T2>&);

  template <class T1, class T2>
  bool operator>(const pair<T1, T2>&,
                 const pair T1, T2>&);

  template <class T1, class T2>
  bool operator<=(const pair<T1, T2>&,
                 const pair T1, T2>&);

  template <class T1, class T2>
  bool operator>=(const pair<T1, T2>&,
                 const pair T1, T2>&);

  template <class T1, class T2>
  pair<T1,T2> make_pair (const T1&, const T2&);
}

first_type

Type of the first element in a pair.

second_type

Type of the second element in a pair.

pair();

Default constructor. Initializes first and second using their default constructors.

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

Creates a pair of types T1 and T2, making the necessary conversions in x and y.

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

Copies first and second from the corresponding elements of p.

~pair ();

template <class T1, class T2>
bool operator== (const pair<T1, T2>& x,
                  const pair T1, T2>& y);

Returns true if (x.first == y.first && x.second == y.second) is true. Otherwise it returns false.

template <class T1, class T2>
bool operator!= (const pair<T1, T2>& x,
                  const pair T1, T2>& y);

Returns !(x==y).

template <class T1, class T2>
bool operator< (const pair<T1, T2>& x,
                const pair T1, T2>& y);

Returns true if (x.first < y.first || (!(y.first < x.first) && x.second < y.second)) is true. Otherwise it returns false.

template <class T1, class T2>
bool operator> (const pair<T1, T2>& x,
                const pair T1, T2>& y);

Returns y < x.

template <class T1, class T2>
bool operator<= (const pair<T1, T2>& x,
                const pair T1, T2>& y);

Returns !(y > x).

template <class T1, class T2>
bool operator>= (const pair<T1, T2>& x,
                const pair T1, T2>& y);

Returns !(x < y).

template <class T1, class T2>
pair<T1,T2>
make_pair(x,y);

Creates a pair by deducing and returning the types of x and y.

<utility>

ISO/IEC 14882:1998 -- International Standard for Information Systems --Programming Language C++, Section 20.2.2