Function Decimal64

cpp/src/arrow/util/decimal.h:173–174

\brief constructor creates a Decimal64 from a BasicDecimal64

  /// \brief constructor creates a Decimal64 from a BasicDecimal64
  constexpr Decimal64(const BasicDecimal64& value) noexcept  // NOLINT runtime/explicit
      : BasicDecimal64(value) {}

  explicit Decimal64(const BasicDecimal32& value) noexcept
      : BasicDecimal64(static_cast<int64_t>(value.value())) {}