Good Job! You have just completed the lesson on arrays, probably the most used data structure in software development. Here is a quick recap of everything:

• Arrays are a special data type that allows you to group together many variables that are related. An array of 100 elements saves you the trouble of having to create 100 variables in your code.

• Arrays can be of any data type, be it primitive, custom-made, or even other arrays.

• Arrays are immutable, so the number of elements must be known at creation time in order for the program to know how much memory to reserve.

• After creation, elements may not be added or deleted from the array.

• Upon creation, an array can be initialized or uninitialized.

• A single dimension uninitialized array is created like this:

  • data_type name[array_size];

• A single dimension initialized array is created like this:

  • data_type name[] = {`first_value’, ‘second_value’, ‘third_value’, …};

• In the initialized case, the size of the array is inferred from the number of elements that are supplied.

• All elements of an array occupy contiguous locations in memory.

• An element in an array can be accessed like so:

  • arr[idx]

• The first element in an array is always at index 0, the last element is at index array_length - 1, the nth element is at index n-1.

• Elements in an array can be modified like this:

  • arr[idx] = new_value

• Since arrays usually contain many elements, the most efficient way to work with them is by using a loop (for loop or while loop).

• Multidimensional arrays are simply arrays of arrays. They are created, accessed, and modified in the same way as their single dimension counterpart.

At this point, you should be comfortable working with arrays when you need to. Use them wisely!