Compiler Error for Nullable Bool

Question

 bool? ispurchased = null;
    var pospurcahsed= ispurchased ? \"1\":\"2\";

Its generating exception .

Cannot implicitly con

Answer 1

You should use .value

bool? ispurchased = null;

if (ispurchased.HasValue)
{
    var pospurcahsed = ispurchased.Value ? "1" : "2";
}

Answer 2

This is not allows because it is unclear what null means in the context of a conditional.

Nullable Booleans can be cast to a bool explicitly in order to be used in a conditional, but if the object has a value if null, InvalidOperationException will be thrown.

It is therefore important to check the HasValue property before casting to bool.

Use like

   var pospurcahsed=  (ispurchased.HasValue && ispurchased.Value) ?......

Nullable Booleans are similar to the Boolean variable type used in SQL. To ensure that the results produced by the & and | operators are consistent with SQL's three-valued Boolean type, the following predefined operators are provided:

bool? operator &(bool? x, bool? y)

bool? operator |(bool? x, bool? y)

or you can use martin suggestion GetValueOrDefault[Thanks to martin to pointing it out ]

The GetValueOrDefault method returns a value even if the HasValue property is false (unlike the Value property, which throws an exception).

Answer 3

You can't use Nullable<bool> or bool? in condition directly, instead use it like:

var pospurcahsed= (ispurchased.HasValue && ispurchased.Value) ? "1":"2";

Answer 4

You can use something like this

 bool? chk = false; 

 //or

 bool? chk2 = false;

 var test = (chk != null && (bool)chk) ? "1": "2";

 //or

 var test2 = (chk2.HasValue && (bool)chk2) ? "1" : "2";

I would suggest don't use var keyword for known types.

Instead of this use Like this:

String test = (chk != null && (bool)chk) ? "1" : "2";

Answer 5

The issue you have is that the conditional operator ? : expects a bool, not a bool?. You could just cast it and be done, but you'd get an InvalidOperationException if the value contained a null, so you should probably check for that first.

Given the name of your variable, I've gone ahead and assumed you'd want to treat a null as you would false, so in the code below I check to ensure it has a value, and if it does then it'll use it in the condition. In the event it doesn't have a value (i.e. it's null then the cast will never happen and you won't get the error (the expression would evaluate to false).

bool? ispurchased = null;
var pospurcahsed = (ispurchased.HasValue && (bool)ispurchased) ? "1":"2";