Built-in Data Types

2.3. Built-in Data Types#

In programming, understanding data types is fundamental. They determine what we can do with each stored value.

In Python, variables can store data of different types, and each type has its own behavior.

Python has the following built-in data types by default:

Text Type:

  • str

Numeric Types:

  • int, float, complex

Sequence Types:

  • list, tuple, range

Mapping Type:

  • dict

Set Types:

  • set, frozenset

Boolean Type:

  • bool

Binary Types:

  • bytes, bytearray, memoryview

Null Type:

  • NoneType

# Examples of variables
nome = "João"  # string (text)
idade = 25     # integer
altura = 1.75  # float (decimal number)
estudante = True  # boolean (True or False)

# Displaying the values
print("Name:", nome)
print("Age:", idade)
print("Height:", altura)
print("Is student?", estudante)

2.3.1. Checking Types#

type(nome), type(idade), type(altura)

2.3.2. Notes on Variable Naming#

A variable can have a simple name (like x or y) or a more descriptive name (age, name, total_volume).

But there are some important rules:

  • ✅ A variable name must start with a letter or an underscore (_)

  • ❌ A variable name cannot start with a number

  • ✅ A variable name can only contain letters, numbers, and underscores (A-Z, a-z, 0-9, _)

  • ⚠️ Names are case-sensitive: idade, Idade, and IDADE are three different variables

2.3.3. Binary Types in Python#

Binary types are used to store data in byte format—that is, in binary format. These types are useful when working with binary files, network communication, image manipulation, audio, and other low-level data.

Python has three main binary data types:

2.3.3.1. 🔹 bytes#

  • An immutable sequence of integer values (0 to 255).

  • Widely used for reading binary files.

2.3.3.2. 🔹 bytearray#

  • Similar to bytes, but it is mutable, meaning its values can be changed.

2.3.3.3. 🔹 memoryview#

  • Allows accessing and manipulating a binary structure (like bytes or bytearray) without copying the data into memory.

# Bytes: immutable sequence
dados_bytes = bytes([10, 20, 30, 40])
print(dados_bytes)
print(type(dados_bytes))  # <class 'bytes'>

# Bytearray: mutable sequence
dados_mutaveis = bytearray([1, 2, 3, 4])
print(dados_mutaveis)
dados_mutaveis[0] = 100  # changing the first value
print(dados_mutaveis)
print(type(dados_mutaveis))  # <class 'bytearray'>

# Memoryview: efficient view of binary data
mem = memoryview(bytes([10, 20, 30, 40]))
print(mem[0])  # accesses the first byte
print(type(mem))  # <class 'memoryview'>

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2.3.4. Null Variable (None)#

In Python, the None value is used to represent the absence of a value or a null value. It indicates that the variable has no data assigned to it. It is equivalent to null in other languages. The type of None is special and is called NoneType.

# Declaring a variable without a value
variable = None

print(variable)
print(type(variable))  # Output: <class 'NoneType'>
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