What is an array?
According to Ruby-Doc.org, arrays are “ordered, integer-indexed collections of any object.” An array can be a collection of strings, integers, etc., and the array syntax is the elements of an array arranged between square brackets, separated by commas:
# Array of strings:
["a", "b", "c", "d"]
#Array of integers:
[1, 2, 3, 4]
Array indexing
The elements in every array are numbered by the order that they appear in the array, and each element’s number is called its index. The first element in any array starts with an index of 0, and the indexes count up for each subsequent element.
Note: Since the first element of an array has an index of 0, that means the second element’s index is 1, the third element’s index is 2, and so on.
Accessing array elements using indexes
Pulling a specific element out of an array is easy using index numbers. You simply call the square brackets ([ ]) on the array with the index number of the element that you’d like in between.
For example, say you had a variable of letters defined as this array: ["a", "b", "c", "d", "e"]. If you wanted to see the second element in letters, you’d run:
letters[1]
Remember that the second element has an index of 1 since indexes start at 0.
The result of the above code would be "b", or the second element in the letters array.
Another example:
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1][0]
In the above case, we have an array of integers that hasn’t been assigned to a variable: [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]. We’re looking to pull out the first element in that array by calling [0] on the array. This code will return 10, or the first element in the array.