Question

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What happens if the first part of an if-structure is false?

if the first criterion yields false in an AND, is the second condition evaluated at all in c# ?

i.e. is a NullException thrown in this example?

if (iAmNull != null && iAmNull.Length == 6) Do();

Answer 1

No the second condition is not evaluated because you are using the short-circuit && operator.

From Wikipedia:

Short-circuit evaluation, minimal evaluation, or McCarthy evaluation
denotes the semantics of some Boolean operators in some programming
languages in which the second argument is only executed or evaluated
if the first argument does not suffice to determine the value of the
expression: when the first argument of the AND function evaluates to
false, the overall value must be false; and when the first argument of
the OR function evaluates to true, the overall value must be true.