How to convert System.Decimal bits to string in C#?

Question

I\'d like to be able to get the bits from a System.Decimal value and then convert that to the string representation of the value, much like Decimal.ToStri

Answer 1

You can use the Decimal constructor Decimal(Int32[]) to convert your value back:

Decimal Constructor (Int32[])

Initializes a new instance of Decimal to a decimal value represented in binary and contained in a specified array.

Afterwards, you can use ToString if you want. Example:

decimal d = 1403.45433M;
int[] nDecimalBits = decimal.GetBits(d);

decimal d2 = new decimal(nDecimalBits);
string s = d2.ToString();

Answer 2

It's does not algoritm, but i suppose it should help.

Decimal bits structure:

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 meaning positive, and 1 meaning negative.

Answer 3

Since you cannot use ToString(), you might want to check out how the mono developers implemented this:

• https://github.com/mono/mono/blob/master/mcs/class/corlib/System/NumberFormatter.cs

The entry point is NumberToString(string, decimal, IFormatProvider).

The interesting part is InitDecHexDigits(uint, ulong), which gets called like this

InitDecHexDigits ((uint)bits [2], ((ulong)bits [1] << 32) | (uint)bits [0]);

and does the "bit juggling and shifting" thing to convert the three integers into binary coded decimals (_val1 to _val4), which can then be (trivially) converted into a string.

(Don't get confused by the fact that they call it "hex representation". It's binary coded decimal digits.)

Answer 4

Is there any major reason you can't just use the decimal constructor?

new decimal(nDecimalBits).ToString();