std::rint, std::lrint, std::llrint — cppreference.com

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Déclaré dans l'en-tête `<cmath>`
`int rint( float arg );`		(depuis C++11)
`int rint( double arg );`		(depuis C++11)
`int rint( long double arg );`		(depuis C++11)
`int rint( Integral arg );`		(depuis C++11)
`long lrint( float arg );`		(depuis C++11)
`long lrint( double arg );`		(depuis C++11)
`long lrint( long double arg );`		(depuis C++11)
`long lrint( Integral arg );`		(depuis C++11)
`long long llrint( float arg );`		(depuis C++11)
`long long llrint( double arg );`		(depuis C++11)
`long long llrint( long double arg );`		(depuis C++11)
`long long llrint( Integral arg );`		(depuis C++11)

Arrondit la arg argument en virgule flottante en une valeur entière en format à virgule flottante, en utilisant le mode d'arrondi courant. Si le résultat est différent de arg (c.-à-arg n'était pas une valeur entière déjà), le FE_INEXACT exception de virgule flottante est élevé .

Original:

Rounds the floating-point argument arg to an integer value in floating-point format, using the current rounding mode. If the result differs from arg (i.e., arg was not an integer value already), the floating-point exception FE_INEXACT is raised.

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Paramètres

arg

valeur du point flottant

Original:

floating point value

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Retourne la valeur

Le résultat entier de arg arrondis

Original:

The integer result of rounding arg

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Notes

La seule différence entre std::nearbyint et std::rint est que std::rint peut soulever la FE_INEXACT exception de virgule flottante, tandis que std::nearbyint jamais elle soulève .

Original:

The only difference between std::nearbyint and std::rint is that std::rint may raise the FE_INEXACT floating-point exception, while std::nearbyint never raises it.

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Exemple

#include <cmath>
#include <cfenv>
#include <iostream>
int main()
{
    #pragma STDC FENV_ACCESS ON
    std::fesetround(FE_DOWNWARD);
    std::cout << "rounding using FE_DOWNWARD:\n" << std::fixed
              << " 12.0 ->  " << std::rint(12.0) << '\n'
              << " 12.1 ->  " << std::rint(12.1) << '\n'
              << "-12.1 -> " << std::rint(-12.1) << '\n'
              << " 12.5 ->  " << std::rint(12.5) << '\n'
              << " 12.9 ->  " << std::rint(12.9) << '\n'
              << "-12.9 -> " << std::rint(-12.9) << '\n'
              << " 13.0 ->  " << std::rint(13.0) << '\n';
    std::fesetround(FE_TONEAREST);
    std::cout << "rounding using FE_TONEAREST: \n"
              << " 12.0 ->  " << std::rint(12.0) << '\n'
              << " 12.1 ->  " << std::rint(12.1) << '\n'
              << "-12.1 -> " << std::rint(-12.1) << '\n'
              << " 12.5 ->  " << std::rint(12.5) << '\n'
              << " 12.9 ->  " << std::rint(12.9) << '\n'
              << "-12.9 -> " << std::rint(-12.9) << '\n'
              << " 13.0 ->  " << std::rint(13.0) << '\n';

    std::cout << "When rounding 12.0 ";
    std::feclearexcept(FE_ALL_EXCEPT);
    std::rint(12.0);
    if(std::fetestexcept(FE_ALL_EXCEPT) & FE_INEXACT) {
        std::cout << "inexact result reported\n";
    } else {
        std::cout << "inexact result not reported\n";
    }

    std::cout << "When rounding 12.1 ";
    std::rint(12.1);
    if(std::fetestexcept(FE_ALL_EXCEPT) & FE_INEXACT) {
        std::cout << "inexact result reported\n";
    } else {
        std::cout << "inexact result not reported\n";
    }
}

Résultat :

rounding using FE_DOWNWARD:
 12.0 ->  12.000000
 12.1 ->  12.000000
-12.1 -> -13.000000
 12.5 ->  12.000000
 12.9 ->  12.000000
-12.9 -> -13.000000
 13.0 ->  13.000000
rounding using FE_TONEAREST: 
 12.0 ->  12.000000
 12.1 ->  12.000000
-12.1 -> -12.000000
 12.5 ->  12.000000
 12.9 ->  13.000000
-12.9 -> -13.000000
 13.0 ->  13.000000
When rounding 12.0 inexact result not reported
When rounding 12.1 inexact result reported

Voir aussi


nearbyint (C++11)	entier le plus proche en utilisant le mode d'arrondi courant Original: nearest integer using current rounding mode The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) [edit]

trunc (C++11)	entier le plus proche n'est pas supérieure en grandeur à la valeur donnée Original: nearest integer not greater in magnitude than the given value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) [edit]

fegetround fesetround (C++11) (C++11)	obtient ou définit direction d'arrondi Original: gets or sets rounding direction The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) [edit]

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