Question

Can I put an object.property which hasn’t been instantiated on the right hand side of an ‘AND’ operator if I know that the left hand side will fail but if the left side passes the right side will be instantiated?

In the example below the first if/else statement sets up the other if statement for the above question. Although I’ve tested that it doesn’t show errors, I was wondering what happens behind the scenes or is there a better way.(there are many if/else statements that use the results of the first if/else statement.

        if (_articleGuid.Equals(Guid.Empty))
        {
            isArticleGuid = false;
        }
        else
        {
            article = new Article(Guid.Empty, _articleGuid);
            bodyText = article.Text;
            articleDate = Convert.ToDateTime(article.DateActive);

            isArticleGuid = true;
        }

        if(isArticleGuid && article.Author != null)
        {
            divAuthor.InnerText = article.Author;                        
        }

Answer 1

Assuming I understand you correctly, this is safe. The article variable will need to be definitely assigned, but the language guarantees that if the LHS expression of an && operator evaluates to false, the RHS expression won’t be evaluated – so you’re not going to get a NullReferenceException.

From the C# 3.0 language specification, section 7.11:

The operation x && y corresponds to the operation x & y, except that y is evaluated only if x is not false.