template<int Prec, typename RoundPolicy_ = DefRoundPolicy>
class decimal64::Decimal< Prec, RoundPolicy_ >
Fixed-point decimal data type for use in deterministic calculations, oftentimes involving money.
- Template Parameters
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| Prec | The number of fractional digits |
| RoundPolicy | Specifies how to round in lossy operations |
Decimal is internally represented as int64_t. It means that it can be passed around by value. It also means that operations with huge numbers can overflow and trap. For example, with Prec == 6, the maximum representable number is about 10 trillion.
Decimal should be serialized and stored as a string, NOT as double. Use Decimal{str} constructor (or Decimal::FromStringPermissive if rounding is allowed) to read a Decimal, and ToString(dec) (or ToStringTrailingZeros(dec)/ToStringFixed<N>(dec)) to write a Decimal.
Use arithmetic with caution! Multiplication and division operations involve rounding. You may want to cast to Decimal with another Prec or RoundPolicy beforehand. For that purpose you can use decimal64::decimal_cast<NewDec>(dec).
Usage example:
std::vector<std::string> cart = ...;
Money sum{0};
for (const std::string& cost_string : cart) {
sum += Money{cost_string};
}
Definition at line 455 of file decimal64.hpp.
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constexpr | Decimal () noexcept=default |
| | Zero by default.
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr | Decimal (Int value) |
| | Convert from an integer.
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| constexpr | Decimal (std::string_view value) |
| | Convert from a string.
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| template<int Prec2> |
| Decimal & | operator= (Decimal< Prec2, RoundPolicy > rhs) |
| | Assignment from another Decimal
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal & | operator= (Int rhs) |
| | Assignment from an integer.
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| constexpr bool | operator== (Decimal rhs) const |
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| constexpr bool | operator!= (Decimal rhs) const |
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| constexpr bool | operator< (Decimal rhs) const |
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| constexpr bool | operator<= (Decimal rhs) const |
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| constexpr bool | operator> (Decimal rhs) const |
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| constexpr bool | operator>= (Decimal rhs) const |
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| constexpr Decimal | operator+ () const |
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| constexpr Decimal | operator- () const |
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| template<int Prec2> |
| constexpr auto | operator+ (Decimal< Prec2, RoundPolicy > rhs) const |
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal | operator+ (Int rhs) const |
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| template<int Prec2> |
| constexpr Decimal & | operator+= (Decimal< Prec2, RoundPolicy > rhs) |
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal & | operator+= (Int rhs) |
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| template<int Prec2> |
| constexpr auto | operator- (Decimal< Prec2, RoundPolicy > rhs) const |
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal | operator- (Int rhs) const |
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| template<int Prec2> |
| constexpr Decimal & | operator-= (Decimal< Prec2, RoundPolicy > rhs) |
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal & | operator-= (Int rhs) |
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| template<typename Int , typename = impl::EnableIfInt<Int>> |
| constexpr Decimal | operator* (Int rhs) const |
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| template<typename Int , impl::EnableIfInt< Int > = 0> |
| constexpr Decimal & | operator*= (Int rhs) |
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| template<int Prec2> |
| constexpr Decimal | operator* (Decimal< Prec2, RoundPolicy > rhs) const |
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| template<int Prec2> |
| constexpr Decimal & | operator*= (Decimal< Prec2, RoundPolicy > rhs) |
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| template<typename Int , typename = impl::EnableIfInt<Int>> |
| constexpr Decimal | operator/ (Int rhs) const |
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| template<typename Int , typename = impl::EnableIfInt<Int>> |
| constexpr Decimal & | operator/= (Int rhs) |
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| template<int Prec2> |
| constexpr Decimal | operator/ (Decimal< Prec2, RoundPolicy > rhs) const |
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| template<int Prec2> |
| constexpr Decimal & | operator/= (Decimal< Prec2, RoundPolicy > rhs) |
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| constexpr int | Sign () const |
| | Returns one of {-1, 0, +1}, depending on the sign of the Decimal
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| constexpr Decimal | Abs () const |
| | Returns the absolute value of the Decimal
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| constexpr Decimal | RoundToMultipleOf (Decimal base) const |
| | Rounds this to the nearest multiple of base according to RoundPolicy
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| constexpr int64_t | ToInteger () const |
| | Returns the value rounded to integer using the active rounding policy.
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| constexpr double | ToDoubleInexact () const |
| | Returns the value converted to double
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| constexpr int64_t | AsUnbiased () const |
| | Retrieve the internal representation.
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| template<typename T > |
| static constexpr Decimal | FromFloatInexact (T value) |
| | Lossy conversion from a floating-point number.
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| static constexpr Decimal | FromStringPermissive (std::string_view input) |
| | Convert from a string, allowing rounding, spaces and boundary dot.
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| static constexpr Decimal | FromUnbiased (int64_t value) noexcept |
| | Reconstruct from the internal representation, as acquired with AsUnbiased
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| static constexpr Decimal | FromBiased (int64_t original_unbiased, int original_precision) |
| | Convert from original_unbiased / 10^original_precision, rounding according to RoundPolicy if necessary.
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template<int Prec, typename RoundPolicy_ = DefRoundPolicy>
| static constexpr Decimal decimal64::Decimal< Prec, RoundPolicy_ >::FromBiased |
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int64_t | original_unbiased, |
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int | original_precision ) |
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inlinestaticconstexpr |
Convert from original_unbiased / 10^original_precision, rounding according to RoundPolicy if necessary.
Usage examples:
Decimal<4>::FromBiased(123, 6) -> 0.0001
Decimal<4>::FromBiased(123, 2) -> 1.23
Decimal<4>::FromBiased(123, -1) -> 1230
- Parameters
-
| original_unbiased | The original mantissa |
| original_precision | The original precision (negated exponent) |
Definition at line 546 of file decimal64.hpp.
template<int Prec, typename RoundPolicy_ = DefRoundPolicy>
template<typename T , int OldPrec, typename OldRound >
| constexpr T decimal_cast |
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Decimal< OldPrec, OldRound > | arg | ) |
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friend |
Cast one Decimal to another Decimal type.
When casting to a Decimal with a lower Prec, rounding is performed according to the new RoundPolicy.
Usage example:
Money cost = ...;
auto discount = decimal64::decimal_cast<Discount>(cost) * Discount{"0.05"};
Definition at line 843 of file decimal64.hpp.
