It's used when you have some API that only takes files, but you need to use a string. For example, to compress a string using the gzip module in Python 2:
import gzip
import StringIO
stringio = StringIO.StringIO()
gzip_file = gzip.GzipFile(fileobj=stringio, mode='w')
gzip_file.write('Hello World')
gzip_file.close()
stringio.getvalue()
Python
docs.python.org › 3 › library › io.html
io — Core tools for working with streams
It deals with streams whose bytes represent text, and handles encoding and decoding to and from strings. TextIOWrapper, which extends TextIOBase, is a buffered text interface to a buffered raw stream (BufferedIOBase). Finally, StringIO is an in-memory stream for text.
GeeksforGeeks
geeksforgeeks.org › python › stringio-module-in-python
StringIO Module in Python - GeeksforGeeks
July 12, 2025 - StringIO is a module in Python that allows you to treat strings as file-like objects. It provides an in-memory stream for text I/O (input/output), which means you can read from and write to a string just like you would with a file, but without ...
02:20
Using io.StringIO to Simulate a File (Video) – Real Python
How to use io.StringIO and io.BytesIO in Python? (Memory | IO | ...
03:18
python stringio example - YouTube
13:23
Aulas Python - 112 - Ferramentas de Sistema VIII: io StringIO, ...
StringIO and operations in Python Tutorial
Top answer 1 of 8
112
It's used when you have some API that only takes files, but you need to use a string. For example, to compress a string using the gzip module in Python 2:
import gzip
import StringIO
stringio = StringIO.StringIO()
gzip_file = gzip.GzipFile(fileobj=stringio, mode='w')
gzip_file.write('Hello World')
gzip_file.close()
stringio.getvalue()
2 of 8
46
StringIO gives you file-like access to strings, so you can use an existing module that deals with a file and change almost nothing and make it work with strings.
For example, say you have a logger that writes things to a file and you want to instead send the log output over the network. You can read the file and write its contents to the network, or you can write the log to a StringIO object and ship it off to its network destination without touching the filesystem. StringIO makes it easy to do it the first way then switch to the second way.
GitHub
github.com › enthought › Python-2.7.3 › blob › master › Lib › StringIO.py
Python-2.7.3/Lib/StringIO.py at master · enthought/Python-2.7.3
the StringIO will start empty. · The StringIO object can accept either Unicode or 8-bit strings, but · mixing the two may take some care. If both are used, 8-bit strings that · cannot be interpreted as 7-bit ASCII (that use the 8th bit) will cause ·
Author enthought
AskPython
askpython.com › python › string › stringio-in-python3
How To Use StringIO In Python3? - AskPython
May 31, 2023 - The different sections related ... is present in the form of a file object, then this StringIO class helps to handle the basic operation over string files....
Readthedocs
pydoc-zh.readthedocs.io › en › latest › library › stringio.html
7.5. StringIO — Read and write strings as files — Python 2.7.6 documentation
This module implements a file-like class, StringIO, that reads and writes a string buffer (also known as memory files). See the description of file objects for operations (section File Objects).
Reddit
reddit.com › r/learnpython › need help with differences between stringio and using physical files
r/learnpython on Reddit: Need help with differences between StringIO and using physical files
October 3, 2018 -
I've just started back at learning Python so tried to modify an old webscrape I wrote in order to not use physical files, I found online StringIO which seemed perfect.
However, when substituting StringIO in place of open() I can't quite figure out where I've gone wrong.
It seems my loop just overwrites the string rather than creating the list it does with a physical file.
Screenshots of outputs
Any pointers would be greatly appreciated
Top answer 1 of 2
2
Please observe the rules in the sidebar --->, especially Posting screenshot of the code is (generally) not allowed. Read posting guidelines. As I can't copy the specific code parts to show you where you went wrong. But the issue is that a StringIO has, just as a file object, a pointer to where you are in the file. Like in a Word document, when you first typed 10 pages of text, the cursor is at the end of the 10th page or just at the 11th, blank page. If you then want to read the contents back, you need to go to the start of the document (Ctrl+Home I believe) or scroll to the top. That 's what you left out in your code, there's f.seek(0) for that. Another thing is that the with f as g: makes no sense in this context. with is meant to have a block that guarantees the object(s) stated after it will be closed/shutdown in some matter (by calling an underlying function on those objects) when the block finishes or an exception is raised. In this case you just want to read something from it and the object is already there, it's even part of the original with statement.
2 of 2
-1
You're not using it properly, look at the examples in the docs https://docs.python.org/2/library/stringio.html
Confessions of a Data Guy
confessionsofadataguy.com › home › you have to try this… from io import stringio, bytesio
You Have to Try This... from io import StringIO, BytesIO - Confessions of a Data Guy
January 2, 2021 - This is where StringIO and BytesIO come in. One way to think about these streams of data is that they act like a File Object. What does that mean? It means you can treat and interact with these objects like you would any other file, the have the File API on-top of them.
Beautiful Soup
tedboy.github.io › python_stdlib › generated › generated › StringIO.StringIO.html
StringIO.StringIO — Python Standard Library
When a StringIO object is created, it can be initialized to an existing string by passing the string to the constructor.
Beautiful Soup
tedboy.github.io › python_stdlib › generated › generated › io.StringIO.html
io.StringIO — Python Standard Library
io.StringIO · View page source · class io.StringIO¶ · Text I/O implementation using an in-memory buffer. The initial_value argument sets the value of object.
Reddit
reddit.com › r/python › is there memory benefit using io.bytesio/stringio vs bytes/str
r/Python on Reddit: Is there memory benefit using io.BytesIO/StringIO vs bytes/str
September 29, 2015 -
Hi r/Python ,
I'm working on a project and want to determine the best internal interface. I know io.BytesIO/StringIO has a file like interface that's compatible with most method that takes a file pointer.
Does io.BytesIO/StringIO behave like files when created with in-memory bytes/str? In a scene that a large file is divided into numbers of logical blocks. It will only read the current block into memory when necessary and write back unnecessary block to disk under memory pressure. I know this caching behavior is done by the kernel, does python do this with io.BytesIO/StringIO?
I'm asking this because the real implementation is hiding under this funny _io module that I have no access to.
from _io import (DEFAULT_BUFFER_SIZE, BlockingIOError, UnsupportedOperation,
open, FileIO, BytesIO, StringIO, BufferedReader,
BufferedWriter, BufferedRWPair, BufferedRandom,
IncrementalNewlineDecoder, TextIOWrapper)Thanks,
Top answer 1 of 2
1
That "funny" _io module is the way that CPython implements modules in C. There are several more of them, e.g. _csv. Typically the Python module attempts to import the faster C code, but if it can't it reverts to a pure Python implementation. To answer your question, from class io.RawIOBase , second paragraph, "Raw binary I/O typically provides low-level access to an underlying OS device or API, and does not try to encapsulate it in high-level primitives (this is left to Buffered I/O and Text I/O, described later in this page).". This is the super class for io.BytesIO. I could not find similar wording for io.StringIO.
2 of 2
1
Both io.BytesIO and io.StringIO are in-memory buffers, so they don't write anything to disk. I think it's a little faster to use them over normal bytes and strs when you need to do repeated concatenation. Otherwise, they're mainly to ducktype a string into a file-like object.
TutorialsPoint
tutorialspoint.com › article › complete-guide-to-python-stringio-module-with-examples
Complete Guide to Python StringIO Module with Examples
March 27, 2026 - The Python StringIO module provides an in-memory file-like object that allows you to work with strings as if they were files. This eliminates the need to create temporary files on disk, making operations faster and more memory-efficient.
O'Reilly
oreilly.com › library › view › python-standard-library › 0596000960 › ch02s05.html
The StringIO Module - Python Standard Library [Book]
May 10, 2001 - The StringIO class implements memory file versions of all methods available for built-in file objects, plus a getvalue method that returns the internal string value.
Author Fredrik Lundh
Published 2001
Pages 304
Beautiful Soup
tedboy.github.io › python_stdlib › generated › StringIO.html
StringIO — Python Standard Library
StringIO · View page source · File-like objects that read from or write to a string buffer. This implements (nearly) all stdio methods.
Python Module of the Week
pymotw.com › 2 › StringIO
StringIO and cStringIO – Work with text buffers using file-like API - Python Module of the Week
Now available for Python 3! Buy the book! ... StringIO provides a convenient means of working with text in memory using the file API (read, write. etc.). There are two separate implementations. The cStringIO version is written in C for speed, while StringIO is written in Python for portability.
Pandas
pandas.pydata.org › docs › reference › api › pandas.read_csv.html
pandas.read_csv — pandas 3.0.4 documentation
By file-like object, we refer to objects with a read() method, such as a file handle (e.g. via builtin open function) or StringIO. ... Character or regex pattern to treat as the delimiter. If sep=None, the C engine cannot automatically detect the separator, but the Python parsing engine can, meaning the latter will be used and automatically detect the separator from only the first valid row of the file by Python’s builtin sniffer tool, csv.Sniffer.
GeeksforGeeks
geeksforgeeks.org › python › python-stringio-and-bytesio-compared-with-open
Python Stringio and Bytesio Compared With Open() - GeeksforGeeks
July 23, 2025 - When you want to manipulate text data in memory without creating temporary files StringIO and BytesIO come. You can create a StringIO or BytesIO object with the test data and pass it to the function as if it were a real file. Below, are the explanation of Python Stringio And Bytesio Compared With Open().
Developpez
python.developpez.com › cours › PythonDocs › lib › module-cStringIO.php
4.6 cStringIO -- Faster version of StringIO - Python
September 19, 2006 - Another difference from the StringIO module is that calling StringIO() with a string parameter creates a read-only object. Unlike an object created without a string parameter, it does not have write methods. These objects are not generally visible.
Python
bugs.python.org › issue15841
Issue 15841: Some StringIO and BytesIO methods can succeed after close - Python tracker
This issue tracker has been migrated to GitHub, and is currently read-only. For more information, see the GitHub FAQs in the Python's Developer Guide · This issue has been migrated to GitHub: https://github.com/python/cpython/issues/60045
GitHub
github.com › JetBrains › python-skeletons › blob › master › StringIO.py
python-skeletons/StringIO.py at master · JetBrains/python-skeletons
December 1, 2021 - The python-skeltons repo is deprecated: use PEP 484 and Typeshed instead - python-skeletons/StringIO.py at master · JetBrains/python-skeletons
Author JetBrains