Question

I have the following OR operator, now currently if the c is null the Error view will be returned and no null exception will be raised on the second check (!c.ManagedBy…); but this will only happen if the compiler perform the (c==null) check before the (!c.Ismanaged..) check.

Book c = elearningrepository.GetBook(id);

if ((c == null) || (!c.IsManagedBy(User.Identity.Name)))
{
    return View("Error");
}

so can I guarantee that the compiler will always perform the c==null check first or it is better to split the above check into two separate If statements to explicitly enforce the sequence.
BR

Answer 1

|| does short-circuit and will evaluate exactly as you have described. There’s no need to separate the statements.

From MSDN:

The conditional-OR operator (||) performs a logical-OR of its bool
operands. If the first operand evaluates to true, the second operand
isn’t evaluated. If the first operand evaluates to false, the second
operator determines whether the OR expression as a whole evaluates to
true or false.

Edited for the most recent MSDN article (2010).