What is a Variable?

I mean it varies. But what else? What is a constant?

Variables are vital for us in any modern programming language. But what exactly is a variable, and can we make an analogy for people reading this article? I say yes, on both counts.

Photo by Pankaj Patel on Unsplash

Difficulty: Beginner | Easy | Normal | Challenging

Prerequisites:

• None, but for practical purposes it would be useful to be able to produce a “Hello, World!” application in your chosen programming language

Terminology

Variable: A named value, that potentially can be changed as the program runs

Variable name: A label for a memory location

Data: Information processed or stored by a computer

Storage: A place where data can be stored

Program: A computer program is a set of instructions to perform a task on a computer

Reference: A pointer to a variable or object

Declaration: Announcing a variable (usually) at the beginning of a program

Naming convention: A set of rules about the names of variables

Value: The something that would be stored in a variable

Assignment: Giving (setting) a variable a value

What are variables?

You might have produced a “Hello, World!” program in your chosen programming language. It is all very well, but limited.

More complex programs need a way of labelling data with a name so it can be referenced later. This has the rather wonderful side-effect of making computer code easier to read (as we can now will our computer code with helpful-sounding names).

We think of variables as containers that hold information and allow us access them later. We will think of this as a box that has a label on it. The label is very useful because it means that we can refer to the box later.

We can visualise this a box that has a value added to it. In the image below we add 4 to myNum, this represents

var myNum = 4