Pair Logical Operator
Демонстрируется использование пары функция логических операторов стандартной библиотеки шаблонов (STL) в Visual C++.
.gif "Примечание") Примечание |
|---|
Только operator< и operator== необходимы для указания все логические операторы. |
template<class _T1, class _T2> inline
bool operator==(
const pair<_T1, _T2>& _X,
const pair<_T1, _T2>& _Y
) {return ( _X.first == _Y.first && _X.second == _Y.second ); }
template<class _T1, class _T2> inline
bool operator<(
const pair<_T1, _T2>& _X,
const pair<_T1, _T2>& _Y
) {return (
_X.first < _Y.first || !( _Y.first < _X.first)
&& _X.second < _Y.second
); }
Заметки
| Примечание |
|---|
Имена класса и параметра в прототипе не соответствует версии в файле заголовка.Некоторые были изменены для улучшения удобочитаемости. |
Функции, описанные в разделе примечаний.
Пример
// paircomp.cpp
// compile with: /EHsc
// Illustrates several comparison operators used to compare two
// pair objects.
//
// Functions:
// operator== - returns true if two pair objects are identical.
//
// operator!= - returns true if two pair objects are not identical.
//
// operator< - returns true for (A < B) if pair object A is less
// than pair object B.
//
// operator<= - returns true for (A <= B) if pair object A is less
// than or equal to pair object B.
//
// operator> - returns true for (A > B) if pair object A is greater
// than pair object B.
//
// operator>= - returns true for (A >= B) if pair object A is greater
// than or equal to pair object B.
/////////////////////////////
#include <iostream>
#include <utility>
using namespace std ;
/* STL pair data type containing int and float */
typedef struct pair<int, float> PAIR_IF;
int main(void)
{
PAIR_IF A(10,3.14f);
PAIR_IF B(18,3.14f);
PAIR_IF C(10,6.28f);
PAIR_IF D(10,3.14f);
/* show pair values */
cout << "A = ( " << A.first << " , " << A.second << " )" << endl;
cout << "B = ( " << B.first << " , " << B.second << " )" << endl;
cout << "C = ( " << C.first << " , " << C.second << " )" << endl;
cout << "D = ( " << D.first << " , " << D.second << " )" << endl;
/* operator== */
if (A==D)
cout << "A and D are equal" << endl;
else
cout << "A and D are not equal" << endl;
/* operator!= */
if (B!=C)
cout << "B and C are not equivalent" << endl;
else
cout << "B and C are equivalent" << endl;
/* operator> */
if (A>C)
cout << "A is greater than C" << endl;
else
cout << "A is not greater than C" << endl;
/* operator>= */
if (A>=C)
cout << "A is greater than or equal to C" << endl;
else
cout << "A is not greater than or equal to C" << endl;
/* operator< */
if (C<D)
cout << "C is less than D" << endl;
else
cout << "C is not less than D" << endl;
/* operator<= */
if (C<D)
cout << "C is less than or equal to D" << endl;
else
cout << "C is not less than or equal to D" << endl;
}
Output
A = ( 10 , 3.14 )
B = ( 18 , 3.14 )
C = ( 10 , 6.28 )
D = ( 10 , 3.14 )
A and D are equal
B and C are not equivalent
A is not greater than C
A is not greater than or equal to C
C is not less than D
C is not less than or equal to D
Требования
заголовок:<служебная программа>