C# ?: Conditional Operator

Question

I have this extract of C# 2.0 source code:

object valueFromDatabase;
decimal result;
valueFromDatabase = DBNull.Value;

result = (decimal)(valueFromDatabase          


        

Answer 1

Your line should be:

result = valueFromDatabase != DBNull.value ? (decimal)valueFromDatabase : 0m;

0m is the decimal constant for zero

Both parts of a conditional operator should evaluate to the same data type

Answer 2

The difference is that the compiler can not determine a data type that is a good match between Object and Int32.

You can explicitly cast the int value to object to get the same data type in the second and third operand so that it compiles, but that of couse means that you are boxing and unboxing the value:

result = (decimal)(valueFromDatabase != DBNull.value ? valueFromDatabase : (object)0);

That will compile, but not run. You have to box a decimal value to unbox as a decimal value:

result = (decimal)(valueFromDatabase != DBNull.value ? valueFromDatabase : (object)0M);