Assign null to decimal using ternary operator

Question

I am using conversion to decimal of a byte array, such that it contains either null or any other number, stored in byte. The problem here is, when I try to convert a null to Nullable decimal, it converts it to zero. I want it to remain null...

Convert.ToDecimal(obj.sal== null ? null : System.Text.Encoding.ASCII.GetString(obj.sal))

Answer 1

If you want the result to potentially be null, then you shouldn't be calling Convert.ToDecimal - which always returns decimal. Instead, you should use:

x = obj.sal == null ? (decimal?) null 
                    : Convert.ToDecimal(Encoding.ASCII.GetString(obj.sal));

Note that you have to cast the null literal to decimal? - or use some other form like default(decimal?) so that the type of the second operand is decimal? - otherwise the compiler won't be able to infer the type of the conditional expression. See this question for more details on that.

Answer 2

Because null is of type object (effectively untyped) and you need to assign it to a typed object.

x = obj.sal == null ? (decimal?) null 
                : Convert.ToDecimal(Encoding.ASCII.GetString(obj.sal));