Python Strings decode() method (original) (raw)

Last Updated : 05 Apr, 2025

The **decode() method in Python is used to convert encoded text back into its original string format. It works as the opposite of encode() method, which converts a string into a specific encoding format. For example, let’s try to encode and decode a simple text message:

Python `

s = "Geeks for Geeks"

e = s.encode('utf-8') print("Encoded text:", e) print(type(e))

d = e.decode('utf-8') print(type(d)) print("Decoded text:", d)

`

Output

Encoded text: b'Geeks for Geeks' <class 'bytes'> <class 'str'> Decoded text: Geeks for Geeks

**Explanation:

• **s.encode(‘ut-8’) encodes the text into bytes format.
• **e.decode(‘utf-8’) decodes the encoded text back to normal unicode format.

Syntax

encoded_string.decode(encoding, errors)

**Parameters:

1. encoding: The encoding format used for decoding (e.g., ‘utf-8‘, ‘**ascii‘).

**2. errors (Optional): Specifies how to handle errors during decoding:

• ‘**strict‘ (default): Raises an error for invalid characters.
• ‘**ignore‘: Ignores errors and proceeds.
• ‘**replace‘: Replaces invalid characters with a placeholder.

**Return Type: Returns the original string after decoding.

Working of the Python Decode() Method

The following flowchart shows the working of Python decoding:

Decode()

Examples of decode() method:

Example 1: Basic Encoding and Decoding

Encoding converts a string into bytes, and **decode() brings it back to its original form.

Python `

t = "Hello, Python!"

Encoding the string into UTF-8

e_t = t.encode('utf-8') print("Encoded:", e_t)

Decoding back to original

d_t = e_t.decode('utf-8') print("Decoded:", d_t)

`

Output

Encoded: b'Hello, Python!' Decoded: Hello, Python!

Explanation:

• **encode(‘utf-8’) converts the string into bytes format.
• **decode(‘utf-8’) restores the original string.

Example 2: Handling Decoding Errors

Sometimes, decoding fails due to incompatible characters. Let’s see how different error-handling modes work:

Python `

Encoding with ASCII (supports only basic English characters)

s = "Café"

Encoding the text in ASCII

enc = s.encode('ascii', errors='replace')

Decoding with strict mode (raises error)

try: print(enc.decode('ascii', errors='strict')) except UnicodeDecodeError as e: print("Decoding Error:", e)

Decoding with ignore mode (ignores errors)

print("Ignored Decoding:", enc.decode('ascii', errors='ignore'))

Decoding with replace mode (replaces errors)

print("Replaced Decoding:", enc.decode('ascii', errors='replace'))

`

Output

Caf? Ignored Decoding: Caf? Replaced Decoding: Caf?

**Explanation:

• **strict mode raises an error when an unsupported character (é) is found.
• **ignore mode removes unsupported characters (é).
• **replace mode replaces unsupported characters with a placeholder (?).

Example 3: Real-World Use Case (Password Encoding & Decoding)

Encoding and decoding help secure sensitive data like passwords. Here’s a simple demonstration.

Python `

import base64

User credentials

user = "user1" passw = "secure@123"

Encoding password

enc_pass = base64.b64encode(passw.encode('utf-8')).decode('utf-8') print("Encoded Password:", enc_pass)

Decoding password for verification

dec_pass = base64.b64decode(enc_pass).decode('utf-8') print("Decoded Password:", dec_pass)

Login verification

e_pass = "secure@123" if e_pass == dec_pass: print("Login Successful!") else: print("Wrong Password!")

`

Output

Encoded Password: c2VjdXJlQDEyMw== Decoded Password: secure@123 Login Successful!

**Explanation:

• The password is encoded in **Base64 to ensure safe storage.
• It is later decoded to verify the login.

Common Use Cases:

• Helps retrieve the original text from an encoded format.
• Essential for handling different character encodings like UTF-8, ASCII, etc.
• Useful in data transmission, security applications, and text processing.

How to use decode in Python 3?

In Python 3, the decode method is used to convert a bytes object into a str (string) object by decoding it from a specific encoding.

Example:

Define a bytes object

bytes_obj = b'Hello, world!'

Decode bytes object to string using UTF-8 encoding

string_obj = bytes_obj.decode('utf-8')

print(string_obj) # Output: Hello, world!

Here, decode(‘utf-8’) converts the bytes object from UTF-8 encoding to a string.

What does .decode(‘utf-8’) do?

The .decode(‘utf-8’) method converts a bytes object into a str object using the UTF-8 encoding. UTF-8 is a variable-width character encoding used for text.

Example:

Define a bytes object with UTF-8 encoding

bytes_obj = b'\xe2\x9c\x94'

Decode bytes object to string

string_obj = bytes_obj.decode('utf-8')

print(string_obj) # Output: ✓

What is string decoding?

String decoding is the process of converting encoded bytes back into a string. It interprets bytes according to a specified character encoding to produce a readable string.

Example:

Define a bytes object

bytes_obj = b'Hello'

Decode bytes object to string

string_obj = bytes_obj.decode('utf-8')

print(string_obj) # Output: Hello

What is an example of decode?

Here’s a basic example of how to use the decode method with a bytes object:

Example:

Define a bytes object

bytes_data = b'Hello, Python!'

Decode bytes object to string using UTF-8 encoding

text = bytes_data.decode('utf-8')

print(text) # Output: Hello, Python!

What is encode() in Python?

The encode() method is used to convert a string into a bytes object using a specific encoding. This is the reverse of decode().

Example:

Define a string

text = 'Hello, world!'

Encode string to bytes using UTF-8 encoding

bytes_obj = text.encode('utf-8')

print(bytes_obj) # Output: b'Hello, world!'

Additional Example of encode():

Define a string

text = 'Hello, Python!'

Encode string to bytes

bytes_data = text.encode('utf-8')

print(bytes_data) # Output: b'Hello, Python!'