c# - vb/c#十进制内部格式

Question

VB 或 C# 中“十进制”值的内部格式是什么？

我不知道这对我现在正在做的任何事情是否重要，但这是最好知道的事情之一。就像，知道有多少位和负数是如何存储的，这意味着当你看到一个负数出现在你期望的正数的地方时，你会立即想到，“啊，有溢出了”，而不是被深深的黑暗之谜所迷惑.

Answer 1

您的问题的答案由 documentation 以完整的彩色提供。 :

The Decimal value type represents decimal numbers ranging from positive 79,228,162,514,264,337,593,543,950,335 to negative 79,228,162,514,264,337,593,543,950,335. The Decimal value type is appropriate for financial calculations requiring large numbers of significant integral and fractional digits and no round-off errors. The Decimal type does not eliminate the need for rounding. Rather, it minimizes errors due to rounding.

A decimal number is a floating-point value that consists of a sign, a numeric value where each digit in the value ranges from 0 to 9, and a scaling factor that indicates the position of a floating decimal point that separates the integral and fractional parts of the numeric value.

The binary representation of a Decimal value consists of a 1-bit sign, a 96-bit integer number, and a scaling factor used to divide the 96-bit integer and specify what portion of it is a decimal fraction. The scaling factor is implicitly the number 10, raised to an exponent ranging from 0 to 28. Therefore, the binary representation of a Decimal value is of the form, ((-2⁹⁶ to 2⁹⁶) / 10^{(0 to 28)}), where -2⁹⁶-1 is equal to MinValue, and 2⁹⁶-1 is equal to MaxValue. For more information about the binary representation of Decimal values and an example, see the Decimal(Int32[]) constructor and the GetBits method.

The scaling factor also preserves any trailing zeroes in a Decimal number. Trailing zeroes do not affect the value of a Decimal number in arithmetic or comparison operations. However, trailing zeroes can be revealed by the ToString method if an appropriate format string is applied.

以及二进制表示，如 GetBits 的文档中所述:

The binary representation of a Decimal number consists of a 1-bit sign, a 96-bit integer number, and a scaling factor used to divide the integer number and specify what portion of it is a decimal fraction. The scaling factor is implicitly the number 10, raised to an exponent ranging from 0 to 28.

The return value is a four-element array of 32-bit signed integers.

The first, second, and third elements of the returned array contain the low, middle, and high 32 bits of the 96-bit integer number.

The fourth element of the returned array contains the scale factor and sign. It consists of the following parts:

Bits 0 to 15, the lower word, are unused and must be zero.

Bits 16 to 23 must contain an exponent between 0 and 28, which indicates the power of 10 to divide the integer number.

Bits 24 to 30 are unused and must be zero.

Bit 31 contains the sign: 0 mean positive, and 1 means negative.

Note that the bit representation differentiates between negative and positive zero. These values are treated as being equal in all operations.