What do you think this piece of code will output?
class Program
{
static void Main(string[] args)
{
Console.WriteLine(GetValue() == (object)true);
Console.WriteLine(object.Equals(GetValue(), true));
}
static object GetValue()
{
return true;
}
}
I won’t be like others and ask you not to run the code. Run the code if you feel like it. I’ll wait here.
…
Back already? Surprised?
I surely have been.. I’ve found a piece of code similar to this as I was cleaning up code in our repository. You have a method that is required to return object (as in System.Object) and you want to check if, unboxed, it holds the value of true (or not).
Why exactly does
GetValue() == (object)true
return false considering that GetValue() returns always a true value? Well… because you are comparing two instances of a System.Object and the ‘==’ operator is coded in a way that uses the ReferenceEquals (and not Equals) method on System.Object.
The author could have unboxed it to a local variable and do the check after but the speed of coding is so much important for some of us.. Thank you ReSharper for pointing this to us and fixing a potentially subtle bug.
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