str()

str(object='', encoding='utf-8', errors='strict')

Returns: str · Updated March 13, 2026 · Built-in Functions

built-in conversion strings type-conversion

The str() function converts an object to its string representation. It is one of the most frequently used built-in functions in Python, invoked implicitly whenever you display objects with print() or concatenate values into strings. When called with no arguments, str() returns an empty string. If the object implements __str__(), that method is called; otherwise, __repr__() is used as a fallback.

Syntax

str(object='')
str(bytes_or_buffer, encoding='utf-8', errors='strict')

Parameters

Parameter	Type	Default	Description
`object`	object	`''`	The object to convert to a string. If omitted, returns an empty string. When not a bytes object, calls `object.__str__()` or falls back to `repr()`.
`encoding`	str	`'utf-8'`	The encoding to use when decoding bytes-like objects. Required if passing bytes.
`errors`	str	`'strict'`	Error handling scheme: `'strict'` (raise UnicodeDecodeError), `'ignore'` (skip invalid characters), or `'replace'` (replace with replacement marker).

Returns: A string representation of the object.

Examples

Basic type conversions

# Convert integers to strings
print(str(42))
# 42

# Convert floats
print(str(3.14159))
# 3.14159

# Convert lists
print(str([1, 2, 3]))
# [1, 2, 3]

# Convert None
print(str(None))
# None

Working with bytes and encoding

When converting bytes to strings, you must specify the encoding. This is where str() behaves like bytes.decode():

# Decode UTF-8 bytes
print(str(b'hello', 'utf-8'))
# hello

# Handle special characters
print(str(b'caf\xc3\xa9', 'utf-8'))
# café

# Error handling - ignore invalid bytes
print(str(b'hello\x80world', 'utf-8', 'ignore'))
# helloworld

# Error handling - replace with placeholder
print(str(b'hello\x80world', 'utf-8', 'replace'))
# hello�world

Custom objects with str

Classes can define __str__() to customize their string representation:

class User:
    def __init__(self, name, age):
        self.name = name
        self.age = age
    
    def __str__(self):
        return f"User({self.name}, {self.age})"

user = User("Alice", 30)
print(str(user))
# User(Alice, 30)

Objects without __str__() fall back to repr():

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

p = Point(3, 4)
print(str(p))
# <__main__.Point object at 0x...>

Common Patterns

String concatenation with str()

# Building strings from multiple values
name = "Alice"
age = 30
message = "Hello, " + name + ", you are " + str(age) + " years old."
print(message)
# Hello, Alice, you are 30 years old.

Converting user input

# Input always returns a string
user_input = input("Enter a number: ")
number = int(user_input)  # Convert string to int
print(number * 2)

Safe string conversion in logging

# Convert any object to string for logging (never raises)
def log_value(value):
    return str(value)

print(log_value([1, 2, 3]))
# [1, 2, 3]
print(log_value({"key": "value"}))
# {'key': 'value'}

Reading file content as strings

# Reading bytes from a file and decoding
with open("data.txt", "rb") as f:
    content = f.read()
    text = str(content, "utf-8")

Errors

TypeError with incorrect arguments

# Missing encoding when passing bytes
str(b"hello")
# TypeError: string argument without an encoding

# Too many positional arguments
str("hello", "utf-8")
# TypeError: str() argument 'errors' must be str, not None

UnicodeDecodeError with wrong encoding

# Invalid UTF-8 sequence with strict error handling
str(b"\xff\xfe", "utf-8", "strict")
# UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff...