I was just wondering why the following code doesn't work (please keep in mind that I set age to be nullable):
myEmployee.age = conditionMet ? someNumber : null;
Yet the following works fine:
if(conditionMet)
{
myEmployee.age = someNumber;
}
else
{
myEmployee.age = null;
}
Why can't I set the value to null in a conditional operator?? All these if statements in my code is not nice.
Thanks.
The types on both sides have to be the same (or be implicitly convertible):
myEmployee.age = conditionMet ? someNumber : (int?)null;
From the docs:
Either the type of first_expression and second_expression must be the same, or an implicit conversion must exist from one type to the other.
null instead of casting as (int?)someNumber? Do you find that more readable? I only ask because both you and RedFilter chose the same side.
int is logically convertible to a nullable integer but null is not logically convertible to an integer.You can, just be clear about the type that null should be interpreted as:
myEmployee.age = conditionMet ? someNumber : (int?)null;
Look at what the documentation has to say:
[MSDN] The default value for a nullable type variable sets HasValue to false. The Value is undefined.
The default is thus null. Which means that you can simply do:
if (conditionMet)
myEmployee.age = someNumber;
There is no need for more obscure code syntax.
If required you can initialize it with null in advance, if it somehow was not the default, like so:
myEmployee.age = null;
if (conditionMet)
myEmployee.age = someNumber;
The types of the parts of the ternary statement must be implicitly castable to a common base. In the case of int and null, they aren't. You can solve this by making age a Nullable<int> (or int?) and casting someNumber to int?.
EDIT to clarify: you can set the value to null with a ternary statement with proper casting. The problem here isn't that you're trying to set a value to null with a ternary statement. It's that the compiler-inferred return types of the two expressions involved in the ternary statement cannot be implicitly casted to a common base type.
ifstatements are statements (i.e. without value); the conditional operator?:is an expression (and hence why you've had this issue as the types must be the same or implicitly convertible).