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    std::rel_ops::operator!=,>,<=,>=

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    <metanoindex/>

     
    C++
     
    Bibliothèque d'utilitaires
     
    <tbody> </tbody>
    Déclaré dans l'en-tête <utility>
    template< class T > bool operator!=( const T& lhs, const T& rhs );
    		 (1)
    template< class T > bool operator>( const T& lhs, const T& rhs );
    		 (2)
    template< class T > bool operator<=( const T& lhs, const T& rhs );
    		 (3)
    template< class T > bool operator>=( const T& lhs, const T& rhs );
    		 (4)
    Étant donné défini par l'utilisateur operator== et operator< pour les objets de T type, met en œuvre les sens habituel d'autres opérateurs de comparaison .
    Original:
    Given a user-defined operator== and operator< for objects of type T, implements the usual semantics of other comparison operators.
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    1)

    Met en œuvre operator!= en termes de operator== .
    Original:
    Implements operator!= in terms of operator==.
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    2)

    Met en œuvre operator> en termes de operator< .
    Original:
    Implements operator> in terms of operator<.
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    3)

    Met en œuvre operator<= en termes de operator< .
    Original:
    Implements operator<= in terms of operator<.
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    4)

    Met en œuvre operator>= en termes de operator< .
    Original:
    Implements operator>= in terms of operator<.
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    Paramètres

    lhs -
    gauche argument
    Original:
    left-hand argument
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    rhs -
    droite argument
    Original:
    right-hand argument
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    Retourne la valeur

    1)

    Retours true si lhs' est pas égal à rhs .
    Original:
    Returns true if lhs is not equal to rhs.
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    2)

    Retours true si lhs est plus que rhs .
    Original:
    Returns true if lhs is greater than rhs.
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    3)

    Retours true si lhs' est inférieure ou égale à rhs .
    Original:
    Returns true if lhs is less or equal to rhs.
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    4)

    Retours true si lhs est' plus ou égale à rhs .
    Original:
    Returns true if lhs is greater or equal to rhs.
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    Mise en œuvre possible

    First version 
    namespace rel_ops {
    template< class T >
    bool operator!=( const T& lhs, const T& rhs ) 
    {
        return !(lhs == rhs);
    }
}
    Second version 
    namespace rel_ops {
    template< class T >
    bool operator>( const T& lhs, const T& rhs ) 
    {
        return rhs < lhs;
    }
}
    Third version 
    namespace rel_ops {
    template< class T >
    bool operator<=( const T& lhs, const T& rhs ) 
    {
        return !(rhs < lhs);;
    }
}
    Fourth version 
    namespace rel_ops {
    template< class T >
    bool operator>=( const T& lhs, const T& rhs ) 
    {
        return !(lhs < rhs);
    }
}

    Exemple

    #include <iostream>
#include <utility>

struct Foo {
    int n;
};

bool operator==(const Foo& lhs, const Foo& rhs)
{
    return lhs.n == rhs.n;
}

bool operator<(const Foo& lhs, const Foo& rhs)
{
    return lhs.n < rhs.n;
}

int main()
{
    Foo f1 = {1};
    Foo f2 = {2};
    using namespace std::rel_ops;

    std::cout << std::boolalpha;
    std::cout << "not equal?     : " << (bool) (f1 != f2) << '\n';
    std::cout << "greater?       : " << (bool) (f1 > f2) << '\n';
    std::cout << "less equal?    : " << (bool) (f1 <= f2) << '\n';
    std::cout << "greater equal? : " << (bool) (f1 >= f2) << '\n';
}

    Résultat : 

    not equal?     : true
greater?       : false
less equal?    : true
greater equal? : false