String encoding

Convert Unicode text to binary data for I/O or storage.

File I/O: writing text to a binary file opened with 'wb' mode, Network programming: sending strings over a socket that requires bytes, Cryptography: hashing text input with hashlib

Common in file I/O, network programming, cryptography, and any API expecting bytes.

text.encode(encoding)

... .encode(...)

text: str (the string to encode), encoding: str (e.g., 'utf-8', 'utf-16', 'latin-1')

• open(file
• 'wb')
• base64.b64encode()
• hashlib.sha256()

• Using other encodings like 'utf-16' or 'latin-1'
• using .decode() for reverse operation.

Calling .encode() on an already-bytes object: misconception that any text-like value is a str → AttributeError; Omitting the encoding argument: misconception that default is always safe → platform-dependent behavior on Python 2 or unusual configs; Assuming .encode() returns a str: misconception about return type → TypeError when passing result to str-expecting APIs

.decode() converts bytes back to str; using str() on bytes without decoding yields representation.

Coming from C: assuming strings are already byte arrays and skipping .encode() → Python str is Unicode; call .encode() to obtain bytes; Coming from Java: expecting getBytes() → Python uses .encode() with UTF-8 as default

• string encoding
• decoding
• bytes conversion
• base64 encoding

Avoid .encode() when the receiving API already accepts str; only use when bytes are explicitly required. Creates a new bytes object each call — avoid repeated encoding in tight loops on large strings. The errors parameter ('strict', 'ignore', 'replace', 'surrogateescape') controls handling of unencodable characters; default 'strict' raises UnicodeEncodeError.

Ensures safe binary representation of text for storage or transmission, avoiding encoding mismatches.

Think 'UTF-8 encode to bytes' when you need to send text over the wire.

Remember that str.encode() returns a new bytes object; the original string is unchanged. Use the errors parameter (e.g., 'ignore' or 'replace') to handle invalid characters for the chosen encoding.

Using codecs.encode() for custom error handling, or using .encode('utf-8', 'surrogatepass') for advanced handling.