.NET/C# decimal serialization problems

Question

I have a class with a decimal property & I'm serializing & deserializing using JSON.NET. The problem I'm having is that if say the decimal value is 100000000000023063.0 , when I deserialize it gets converted to 100000000000023000. I have checked the JSON & it's definitely recorded as 100000000000023063.0.

I've looked into it &

decimal.Parse("100000000000023063.0")

=

100000000000023063.0

but

var d = (decimal)100000000000023063.0

=

100000000000023000

I can get around this problem by storing as a string & have a property that does decimal.Parse() but does anyone know why this is happening?

Answer 1

It's because 100000000000023063.0 is a double constant, which you're then converting to decimal, and precision is getting lost.

Write it like this instead:

var d = 100000000000023063.0M;

The M suffix tells the C# compiler that the number is a decimal constant.

In fact you don't even need the decimal separator for this - i.e. 1M == 1.0M and both are decimals.

Answer 2

It is because you are casting a double to a Decimal whereas you should be defining the value as a Decimal: i.e.

var q = 100000000000023063.0M;

The M suffix indicates that the numeric constant is of type Decimal