Why is Decimal described as fixed point?

Question

From MSDN:

A decimal number is a signed, fixed-point value consisting of an integral part and an optional fractional part. The integral and fractional parts consist of a series of digits that range from zero to nine (0 to 9), separated by a decimal point symbol.

I thought it was a floating point number with base 10.

Answer 1

Yes, it is a floating point number. That's very old documentation - it was fixed in the .NET 2.0 docs.

(It's unclear whether this was due to me submitting a correction or whether other people had as well. I do remember having to justify my position time and time again, where I thought it was pretty clear - if Decimal was a fixed point type, why did each value include an exponent? I also remember having arguments in C# newsgroups about this, where people were clinging to the documentation as evidence that it really was a fixed point type. Oh well.)

Answer 2

I think it's because you're looking at the .NET 1.1 version of Decimal. The 3.5 version states:

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.