The decimal Type

A decimal is a structure representing a floating-point decimal number. The main difference between a decimal and a float or a double is that a decimal can store any value that can be written using no more than 28 decimal digits, a decimal point, and optionally a ‘-’, without rounding. For example, the value 0.1 cannot be stored exactly in either a float or a double because its binary representation is infinite (0.000110011…); however, it can be stored exactly in a decimal. Various types, such as int, double, or string, may be converted to a decimal using a Convert.ToDecimal method; for example, if i is an int, we can convert it to a decimal with:

decimal d = Convert.ToDecimal(i);

A decimal is represented internally with the following three components:

• A 96-bit value v storing the digits (0 ≤ v ≤ 79,228,162,514,264,337,593,543,950,335).
• A sign bit s, where 1 denotes a negative value.
• A scale factor d to indicate where the decimal point is (0 ≤ d ≤ 28).

The value represented is then (-1)^sv/10^d. For example, 123.456 can be represented by setting v to 123,456, s to 0, and d to 3.