When is the appropriate time to use "a" vs "an"?
For example, "I have a array of..." vs "I have an array of..."
I may be mistaken but I would typically use an in this case.
Firstly, am I correct to use an in this case? Secondly, is there a rule of thumb or grammatical rule that defines the appropriate usage? Lastly, If there is a grammatical rule, what is a recognized resource to its definition?