How much more expensive is an Exception than a return value?

Question

Is it possible to change this code, with a return value and an exception:

public Foo Bar(Bar b)
{
   if(b.Success)
   {
      return b;
   }
   else
   {
      throw n.Exception;
   }
}

to this, which throws separate exceptions for success and failure

public Foo Bar(Bar b)
{
   throw b.Success ? new BarException(b) : new FooException();
}

try
{
   Bar(b)
}
catch(BarException bex)
{
   return ex.Bar;
}
catch(FooException fex)
{
   Console.WriteLine(fex.Message);
}

Answer 1

Throwing an exception is definitely more expensive than returning a value. But in terms of raw cost it's hard to say how much more expensive an exception is.

When deciding on a return value vs. an exception you should always consider the following rule.

Only use exceptions for exceptional circumstances

They shouldn't ever be used for general control flow.