Data Types

In Python we have several built-in data types. The most common types of data that you will find are numbers, strings and booleans.

Key points

Python is dynamically typed, meaning you don’t need to declare the type of a variable explicitly.
You can use the type() function to check the data type of a variable.
Data types determine what operations can be performed on the data.
You can convert between different data types using built-in functions like int(), float() and str()

Numeric Types

Description	Type	Example
integers or whole numbers	int	a = int(12)
floating-point numbers	float	b = float(7.3)

a = 12
b = 7.3
print("A:", a, type(a))
print("B:", b, type(b))

A: 12 <class 'int'>
B: 7.3 <class 'float'>

Text Types

Description	Type	Example
textual data (strings)	str	a = “Jean Golding”

name = "Jean Golding"
print("Name:", name, type(name))

Name: Jean Golding <class 'str'>

Note that

It’s important that when writing numbers in your scripts, you do not put quotation marks around them, otherwise they will be recognized by the Python interpreter as strings. There is a difference between 3.14159 and “3.14159”, the first is a number and the second is just a pair of characters.

pi = 3.14159
print("pi:", pi, type(pi))

pi: 3.14159 <class 'float'>

pi = "3.14159"
print("pi:", pi, type(pi))

pi: 3.14159 <class 'str'>

Boolean Types

Description	Type	Example
boolean values (True or False)	bool	a = True

a = 23
b = 2
print(a != b)

True

We can assign this boolean value to a variable:

c = (a != b)
print("c:", c, type(c))

c: True <class 'bool'>

Note the use of the brackets around a != b. This isn’t necessary here, but it can help to make the code clearer!

Exercise

Without using Python, can you tell what is the data type of these variables?

x = 32
number_of_participants = "1017"
Friday = True
y = float(1)
a = 10<8

Answer

x is an integer

number_of_participants is a string

Friday is a boolean

y is a float

a is a boolean