Clarify stdout flush behavior for newline characters in print()

This PR adds a note to the print() documentation to clarify how Python’s stdout buffering works with newline (\n) characters inside a single print call.

Motivation:

Current documentation mentions that flush() is implied for writes containing newlines.

However, it does not explain that Python flushes only after the entire write operation, not mid-string.

This can confuse users coming from C, who expect a flush at each newline, and developers writing scripts that rely on immediate output for progress indicators or CLI feedback.


What’s added:

A .. note:: block explaining that stdout behavior depends on the environment (TTY vs redirected stdout).

Guidance on explicitly flushing with flush=True or sys.stdout.flush().

Mention of python -u for unbuffered output.

A short example demonstrating the behavior.


Impact:

Improves clarity for learners and developers.

Aligns documentation with actual behavior across different environments.

Not a behavior change — documentation-only PR.


Related Issue:

Addresses issue #141395

Author: Vemulakonda559

Doc/library/functions.rst

@@ -1616,6 +1616,31 @@ are always available.  They are listed here in alphabetical order.
    Output buffering is usually determined by *file*.
    However, if *flush* is true, the stream is forcibly flushed.
 
+.. note::
+
+   In Python, printing a string containing newline characters does not automatically flush stdout. 
+   Python performs buffering at the write/operation level, so newlines inside a single write 
+   do not necessarily trigger an immediate flush. The exact timing of output may vary depending 
+   on the environment:
+
+   - When stdout is connected to a terminal (TTY), output is line-buffered and typically flushes 
+     after the write completes.
+   - When stdout is redirected to a file or pipe, output may be fully buffered and not flush 
+     until the buffer fills or flush is requested.
+
+   For guaranteed immediate output, use ``flush=True`` or call ``sys.stdout.flush()`` explicitly. 
+   Running Python with the ``-u`` flag also forces unbuffered output, which may be useful in 
+   scripts requiring immediate writes.
+
+   Example:
+
+   .. code-block:: python
+
+      from time import sleep
+
+      print("Hello\nWorld", end='')  # Both lines appear together on TTY
+      sleep(3)
+      print("Hi there!")
 
    .. versionchanged:: 3.3
       Added the *flush* keyword argument.