sysstdinbuffer

sys.stdin.buffer is a binary buffered interface to the standard input stream in Python 3. It is accessed via the buffer attribute of sys.stdin, where sys.stdin is a TextIOWrapper representing standard input as text. sys.stdin.buffer returns a BufferedReader that yields bytes objects when read, bypassing text encoding, newline translation, and other text processing performed by the text wrapper.

Difference from sys.stdin: sys.stdin reads and decodes input into text using the default encoding and may translate newlines. In contrast, sys.stdin.buffer provides the raw bytes as they arrive from the operating system, allowing low-level binary I/O, precise control over encoding, and potentially better performance for large inputs or binary data.

Common usage: import sys; b = sys.stdin.buffer.read(n) to read n bytes; line = sys.stdin.buffer.readline() to read a line as bytes; for chunk in sys.stdin.buffer: iterate over lines as bytes; data = sys.stdin.buffer.read() to read until EOF. The returned objects are bytes, not strings, so decoding must be performed explicitly when text is required.

Caveats: When using sys.stdin.buffer, you must decode bytes yourself if you need text, choosing an appropriate encoding (for example, b.decode('utf-8')). Mixing sys.stdin and sys.stdin.buffer can lead to inconsistencies in buffering and encoding behavior. Some interactive environments or higher-level libraries may prefer the text interface, while binary or performance-sensitive code may rely on the buffer.

See also: sys.stdin; the io module; binary versus text I/O in Python 3.