Arrays
Computer Science: OCR GCSE, topic 2.2.11
Arrays
Arrays are really useful when you have access to large amounts of related data, but you don't want to store in multiple variables.
Arrays
- Arrays are a data structure that stores a fixed number of values under a single identifier.
- The values must be of the same type.
Array elements
- Each piece of data inside an array is called an element.
- Each element has an index, which is its position within the array.
- We start counting the indices from 0.
Arrays in pseudocode
- An array of ten items can be created using the following syntax:
- array name_of_array[10]
- Values can be assigned as follows:
- name_of_array[0] = "Hello"
- Values can be accessed as follows:
- print(name_of_array[0])
2D Arrays
A 2D array is the data structure which consists of an array of arrays.
2D Array
- A 2D array is a data structure where arrays are filled with other arrays.
- This can be used to represent a 2D surface, or records.
Accessing elements
- To access an individual array, we can access the array as usual:
- array = my2DArray[4]
- To access an individual element, we use this syntax:
- array[5][0]
- This would get the first element of the sixth array.
Applications of 2D arrays
- 2D arrays are often used to represent a 2D surface, for example a chess board:
- Each element of the 2D array could contain the chess piece in that location.
- 2D arrays can be used to represent a database:
- The outer array stores a collection of records.
- The inner arrays store a single record.
Test yourself on Arrays
Toggle until all are correct: Which of these is true of arrays?
How do we access the first element of an array?
What would the command "array[5][3] = 0" do to a 2D array?