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std::numeric_limits::round_style

Da cppreference.com.

 
 
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initializer_list(C++11)
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Tipi base
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static const std::float_round_style round_style
(C fino + 11)
static constexpr std::float_round_style round_style
(dal C++11)
Il valore del std::numeric_limits<T>::round_stylem identifica lo stile di arrotondamento usato dalla virgola mobile T tipo ogniqualvolta un valore che non è uno dei valori esattamente repesentable di T è memorizzato in un oggetto di quel tipo.
Original:
The value of std::numeric_limits<T>::round_stylem identifies the rounding style used by the floating-point type T whenever a value that is not one of the exactly repesentable values of T is stored in an object of that type.
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[modifica] Specializzazioni standard

T
valore di std::numeric_limits<T>::round_style
Original:
value of std::numeric_limits<T>::round_style
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/* non-specialized */ std::round_toward_zero
bool std::round_toward_zero
char std::round_toward_zero
signed char std::round_toward_zero
unsigned char std::round_toward_zero
wchar_t std::round_toward_zero
char16_t std::round_toward_zero
char32_t std::round_toward_zero
short std::round_toward_zero
unsigned short std::round_toward_zero
int std::round_toward_zero
unsigned int std::round_toward_zero
long std::round_toward_zero
unsigned long std::round_toward_zero
long long std::round_toward_zero
unsigned long long std::round_toward_zero
float
di solito std::round_to_nearest
Original:
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double
di solito std::round_to_nearest
Original:
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long double
di solito std::round_to_nearest
Original:
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[modifica] Esempio

Il 0.1 valore decimale non può essere rappresentato da un binario in virgola mobile. Se conservato in un IEEE-745 double, cade tra 0x1.9999999999999*2-4
e 0x1.999999999999a*2-4
. Arrotondamento al più vicino valore risulta rappresentabili in 0x1.999999999999a*2-4
.
Original:
The decimal value 0.1 cannot be represented by a binary floating-point type. When stored in an IEEE-745 double, it falls between 0x1.9999999999999*2-4
and 0x1.999999999999a*2-4
. Rounding to nearest representable value results in 0x1.999999999999a*2-4
.
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Allo stesso modo, il valore decimale 0.3, che è tra 0x1.3333333333333*2-2
e 0x1.3333333333334*2-2
è arrotondato al più vicino ed è archiviato come 0x1.3333333333333*2-2
.
Original:
Similarly, the decimal value 0.3, which is between 0x1.3333333333333*2-2
and 0x1.3333333333334*2-2
is rounded to nearest and is stored as 0x1.3333333333333*2-2
.
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#include <iostream>
#include <limits>
int main()
{
    std::cout << std::hexfloat << "The decimal 0.1 is stored in a double as "
              << 0.1 << '\n'
              << "The decimal 0.3 is stored in a double as "
              << 0.3 << '\n'
              << "The rounding style is " << std::numeric_limits<double>::round_style << '\n';
}

Output:

The decimal 0.1 is stored in a double as 0x1.999999999999ap-4
The decimal 0.3 is stored in a double as 0x1.3333333333333p-2
The rounding style is 1

[modifica] Vedi anche

indica virgola mobile modalità di arrotondamento
Original:
indicates floating-point rounding modes
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(enum) [edit]