How do I safely cast a System.Object to a `bool` in C#?

Question

I am extracting a bool value from a (non-generic, heterogeneous) collection.

The as operator may only be used with reference types, so it is no

Answer 1

There are two options... with slightly surprising performance:

• Redundant checking:

  if (rawValue is bool)
  {
      bool x = (bool) rawValue;
      ...
  }
  

• Using a nullable type:

  bool? x = rawValue as bool?;
  if (x != null)
  {
      ... // use x.Value
  }
  

The surprising part is that the performance of the second form is much worse than the first.

In C# 7, you can use pattern matching for this:

if (rawValue is bool value)
{
    // Use value here
}

Note that you still end up with value in scope (but not definitely assigned) after the if statement.