How heavy .NET exception handling is?

Question

Sometimes I have this situation when it's quite easier to wrap whole piece of code in try-catch block rather than do a lot of checking which violently reduce code readability. For example, this

var result = string.Empty;
if (rootObject != null)
{
    if (rootObject.FirstProperty != null)
    {
        if (rootObject.FirstProperty.SecondProperty != null)
        {
            if (!string.IsNullOrEmpty(rootObject.FirstProperty.SecondProperty.InterestingString))
            {
                result = rootObject.FirstProperty.SecondProperty.InterestingString;
            }
        }
    }
}

I really prefer to do like this

var result = string.Empty;
try
{
    result = rootObject.FirstProperty.SecondProperty.InterestingString;
}
catch { }

But after code review I often hear from my mentor that I should avoid try-catch blocks when it's possible to make simple checking. Is it really so critical and each try-catch block eating a lot of system resources (relatively)? Is this resources used only when error raised or each case (successfull or not) is equally "heavy"?

Answer 1

Whether exceptions are heavyweight or lightweight is completely irrelevant. A thrown exception that could have been easily prevented is a bug. Do not catch the exception: fix the bug so that you don't have to.