Basic Variable Types

by Martin D. Maas, Ph.D

Introduction to Variable Types

One of the first things we said about Julia, is that it is an optionally typed language. That is, we can write code without specifying the type of each variable.

For example, we can do the following:

a = 1 + 1         
typeof(a)       # Int64

a = "Hello"     
typeof(a)       # String

Not that the variable a was first an Integer, then a String, and we didn’t have to be explicit about that. We just assigned corresponding values, and the language took care of whatever was needed.

Even though this kind of behavior is valid, we can’t go very far by ignoring what is happening under the hood with variable types.

So, even on a first approach to the language, it is a good idea to know something about variable types.

The Julia type system is very complex indeed, and in this first approach we will only cover the most basic types, their conversion, and some common gotchas.