Data types

To understand data types, you need to understand that there are two ‘types’ of programming languages:

• statically typed languages
• dynamically typed languages

What are dynamically typed languages?

Dynamically typed languages don’t require you to give a variable a data type when you create it. Instead, types don’t really exist and the language just figures out how best to store the variable based on the value you give it.

An example of a dynamically typed language is Python. We can give any variable data of any type:

x = 5          # x is an integer
x = "hello"    # now x is a string

What are statically typed languages?

Statically typed languages (such as C) do require you to give a variable a data type when you create it. This means that the variable can only hold data of that type.

For example, in C we can create an integer variable like this:

int x = 5; // x is an integer

If we try to give x a string value later on, we’ll get an error:

x = "hello"; // Error: cannot convert char* to int

Common data types

These are some important data types that we’ll cover in future chapters!

Data Type	Description	Example Values
int	Integer (whole) numbers	1, -5, 42
float	Floating-point (decimal) numbers	3.14, -0.001, 2.0
string	Text, really an array of chars	”hello world”, “123”
bool	Boolean values (true or false)	true, false
char	Single character	’a’, ‘Z’, ‘1’
array	Collection of values of the same type	[1, 2, 3], [“a”, “b”]
object	An instance of a struct	struct Person {char* name; int age;}