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Unit 6: Array

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do you create an array of a fixed size, and how do you read or change the element at a given index?

Topic 6.1 Array Creation and Access: declare and initialise a one-dimensional array, access elements by index from 0 to length minus 1, and use the length attribute.
A focused answer to AP CSA Topic 6.1, covering how to declare and create a one-dimensional array, default element values, the length attribute, accessing and modifying elements by index, the valid index range, and ArrayIndexOutOfBoundsException, with a fully worked example.
11 min answer →

What are the standard array algorithms - finding a sum, maximum, minimum, count or average - and how do you write them?

Topic 6.4 Developing Algorithms Using Arrays: write and apply standard algorithms over a one-dimensional array, including finding minimum, maximum, sum, average, count and shifting or rearranging elements.
A focused answer to AP CSA Topic 6.4, covering the standard array algorithms - sum, average, minimum, maximum, count, search, and rearranging elements - the accumulator and running-best patterns, and how to combine them, with a fully worked example.
12 min answer →

When is the enhanced for loop the cleaner way to read every element of an array, and what can it not do?

Topic 6.3 Enhanced for Loop for Arrays: use an enhanced for-each loop to traverse the elements of an array, and explain why it cannot modify the array or access indices.
A focused answer to AP CSA Topic 6.3, covering the enhanced for-each loop syntax for arrays, how the loop variable holds a copy of each element, why it cannot change array elements or give the index, and when to use it versus a standard indexed loop, with a fully worked example.
10 min answer →

How do you visit every element of an array in order using a standard for loop driven by the index?

Topic 6.2 Traversing Arrays: use a standard for loop with an index variable to traverse an array, reading or modifying each element, while staying inside the valid index bounds.
A focused answer to AP CSA Topic 6.2, covering how to traverse a one-dimensional array with a standard indexed for loop, the correct loop bounds, reading versus modifying elements, partial traversals, and avoiding off-by-one errors and out-of-bounds exceptions, with a fully worked example.
11 min answer →