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

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

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Algoritmi

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Libreria matematca

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Localizzazione

Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Utilità libreria

Tipo di supporto (basic types, RTTI, type traits)

Gestione della memoria dinamica

La gestione degli errori

Programma di utilità

Funzioni variadic

Data e ora

Funzione oggetti

initializer_list (C++11)

bitset

hash (C++11)

Gli operatori relazionali Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

Coppie e tuple Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Swap, in avanti e spostare Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Elemento definito nell'header <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)

Dato un definito dall'utente operator==operator< e per gli oggetti di tipo T, implementa la semantica abituali di altri operatori di confronto.

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)

Implementa operator!= in termini di operator==.

Original:

Implements operator!= in terms of operator==.

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2)

Implementa operator> in termini di operator<.

Original:

Implements operator> in terms of operator<.

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3)

Implementa operator<= in termini di operator<.

Original:

Implements operator<= in terms of operator<.

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4)

Implementa operator>= in termini di operator<.

Original:

Implements operator>= in terms of operator<.

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Parametri

lhs	-	sinistra argomento Original: left-hand argument The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
rhs	-	destra argomento Original: right-hand argument The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valore di ritorno

1)

Restituisce true se lhs è' non è uguale a rhs.

Original:

Returns true if lhs is not equal to rhs.

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2)

Restituisce true se lhs è superiore di rhs.

Original:

Returns true if lhs is greater than rhs.

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3)

Restituisce true se lhs' è minore o uguale a rhs.

Original:

Returns true if lhs is less or equal to rhs.

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4)

Restituisce true se lhs è maggiore o uguale arhs.

Original:

Returns true if lhs is greater or equal to rhs.

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Possibile implementazione

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);}}

Esempio

#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};usingnamespace 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';}

Output:

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