CODEWITHSUNDEEP
c#.net
PaulG
PaulG

Reputation: 7102

C#.net can't assign null to a variable in an inline if statement

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.

Upvotes: 5

Views: 4972

Answers (4)

Tamara Wijsman
Tamara Wijsman

Reputation: 12348

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;

Upvotes: 2

Tom Hamming
Tom Hamming

Reputation: 10961

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.

Upvotes: 0

D&#39;Arcy Rittich
D&#39;Arcy Rittich

Reputation: 171411

You can, just be clear about the type that null should be interpreted as:

myEmployee.age = conditionMet ? someNumber : (int?)null;

Upvotes: 8

BrokenGlass
BrokenGlass

Reputation: 160902

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.

Upvotes: 19

Related Questions