Gecko [ fernandoquevedodop.com ]

Name	Size	Permission
2to3.html	70.96 KB	-rw-r--r--
__future__.html	20.75 KB	-rw-r--r--
__main__.html	44.87 KB	-rw-r--r--
_thread.html	30.39 KB	-rw-r--r--
abc.html	46.87 KB	-rw-r--r--
aifc.html	35.56 KB	-rw-r--r--
allos.html	34.33 KB	-rw-r--r--
archiving.html	17 KB	-rw-r--r--
argparse.html	300.89 KB	-rw-r--r--
array.html	37.28 KB	-rw-r--r--
ast.html	293.08 KB	-rw-r--r--
asynchat.html	37.41 KB	-rw-r--r--
asyncio-api-index.html	27.68 KB	-rw-r--r--
asyncio-dev.html	36.1 KB	-rw-r--r--
asyncio-eventloop.html	204.43 KB	-rw-r--r--
asyncio-exceptions.html	17.11 KB	-rw-r--r--
asyncio-future.html	38.23 KB	-rw-r--r--
asyncio-llapi-index.html	61.97 KB	-rw-r--r--
asyncio-platforms.html	21.77 KB	-rw-r--r--
asyncio-policy.html	39.56 KB	-rw-r--r--
asyncio-protocol.html	118.33 KB	-rw-r--r--
asyncio-queue.html	31.86 KB	-rw-r--r--
asyncio-stream.html	69.98 KB	-rw-r--r--
asyncio-subprocess.html	49.25 KB	-rw-r--r--
asyncio-sync.html	42.79 KB	-rw-r--r--
asyncio-task.html	109.14 KB	-rw-r--r--
asyncio.html	17.31 KB	-rw-r--r--
asyncore.html	49.36 KB	-rw-r--r--
atexit.html	22.87 KB	-rw-r--r--
audioop.html	46 KB	-rw-r--r--
audit_events.html	72.85 KB	-rw-r--r--
base64.html	48.09 KB	-rw-r--r--
bdb.html	66 KB	-rw-r--r--
binary.html	15.97 KB	-rw-r--r--
binascii.html	36.3 KB	-rw-r--r--
binhex.html	15.97 KB	-rw-r--r--
bisect.html	43.38 KB	-rw-r--r--
builtins.html	14.87 KB	-rw-r--r--
bz2.html	50.68 KB	-rw-r--r--
calendar.html	69.35 KB	-rw-r--r--
cgi.html	59.95 KB	-rw-r--r--
cgitb.html	19.96 KB	-rw-r--r--
chunk.html	22.21 KB	-rw-r--r--
cmath.html	43.89 KB	-rw-r--r--
cmd.html	50.42 KB	-rw-r--r--
code.html	35.38 KB	-rw-r--r--
codecs.html	157.96 KB	-rw-r--r--
codeop.html	18.26 KB	-rw-r--r--
collections.abc.html	79.17 KB	-rw-r--r--
collections.html	189.43 KB	-rw-r--r--
colorsys.html	17.31 KB	-rw-r--r--
compileall.html	50.68 KB	-rw-r--r--
concurrency.html	24.15 KB	-rw-r--r--
concurrent.futures.html	79.03 KB	-rw-r--r--
concurrent.html	11.56 KB	-rw-r--r--
configparser.html	159.4 KB	-rw-r--r--
constants.html	22.41 KB	-rw-r--r--
contextlib.html	117.2 KB	-rw-r--r--
contextvars.html	38.38 KB	-rw-r--r--
copy.html	17.92 KB	-rw-r--r--
copyreg.html	18.63 KB	-rw-r--r--
crypt.html	28.29 KB	-rw-r--r--
crypto.html	13.93 KB	-rw-r--r--
csv.html	82.89 KB	-rw-r--r--
ctypes.html	295.49 KB	-rw-r--r--
curses.ascii.html	32.04 KB	-rw-r--r--
curses.html	221.24 KB	-rw-r--r--
curses.panel.html	22.16 KB	-rw-r--r--
custominterp.html	11.85 KB	-rw-r--r--
dataclasses.html	113.16 KB	-rw-r--r--
datatypes.html	31.82 KB	-rw-r--r--
datetime.html	374.92 KB	-rw-r--r--
dbm.html	51.16 KB	-rw-r--r--
debug.html	17 KB	-rw-r--r--
decimal.html	270.12 KB	-rw-r--r--
development.html	32.34 KB	-rw-r--r--
devmode.html	31.72 KB	-rw-r--r--
dialog.html	43.03 KB	-rw-r--r--
difflib.html	111.99 KB	-rw-r--r--
dis.html	136.07 KB	-rw-r--r--
distribution.html	13.67 KB	-rw-r--r--
distutils.html	14.73 KB	-rw-r--r--
doctest.html	199.32 KB	-rw-r--r--
email.charset.html	31.92 KB	-rw-r--r--
email.compat32-message.html	97.74 KB	-rw-r--r--
email.contentmanager.html	37.02 KB	-rw-r--r--
email.encoders.html	18.47 KB	-rw-r--r--
email.errors.html	24.45 KB	-rw-r--r--
email.examples.html	60.49 KB	-rw-r--r--
email.generator.html	48.79 KB	-rw-r--r--
email.header.html	37.61 KB	-rw-r--r--
email.headerregistry.html	66.26 KB	-rw-r--r--
email.html	30.75 KB	-rw-r--r--
email.iterators.html	18.23 KB	-rw-r--r--
email.message.html	99.75 KB	-rw-r--r--
email.mime.html	44.89 KB	-rw-r--r--
email.parser.html	57.39 KB	-rw-r--r--
email.policy.html	84.24 KB	-rw-r--r--
email.utils.html	42.57 KB	-rw-r--r--
ensurepip.html	23.9 KB	-rw-r--r--
enum.html	151 KB	-rw-r--r--
errno.html	60.17 KB	-rw-r--r--
exceptions.html	108.44 KB	-rw-r--r--
faulthandler.html	31.5 KB	-rw-r--r--
fcntl.html	36.67 KB	-rw-r--r--
filecmp.html	32.08 KB	-rw-r--r--
fileformats.html	13.52 KB	-rw-r--r--
fileinput.html	40.37 KB	-rw-r--r--
filesys.html	16.78 KB	-rw-r--r--
fnmatch.html	21.02 KB	-rw-r--r--
fractions.html	35.29 KB	-rw-r--r--
frameworks.html	16.15 KB	-rw-r--r--
ftplib.html	71.97 KB	-rw-r--r--
functional.html	12.19 KB	-rw-r--r--
functions.html	260.33 KB	-rw-r--r--
functools.html	92.96 KB	-rw-r--r--
gc.html	40.97 KB	-rw-r--r--
getopt.html	29.4 KB	-rw-r--r--
getpass.html	16.01 KB	-rw-r--r--
gettext.html	98.02 KB	-rw-r--r--
glob.html	27.2 KB	-rw-r--r--
graphlib.html	34.82 KB	-rw-r--r--
grp.html	16.03 KB	-rw-r--r--
gzip.html	45.65 KB	-rw-r--r--
hashlib.html	93.19 KB	-rw-r--r--
heapq.html	42.43 KB	-rw-r--r--
hmac.html	24.74 KB	-rw-r--r--
html.entities.html	14.91 KB	-rw-r--r--
html.html	14.81 KB	-rw-r--r--
html.parser.html	47.7 KB	-rw-r--r--
http.client.html	85.63 KB	-rw-r--r--
http.cookiejar.html	113.94 KB	-rw-r--r--
http.cookies.html	47.64 KB	-rw-r--r--
http.html	45.52 KB	-rw-r--r--
http.server.html	73.05 KB	-rw-r--r--
i18n.html	13.44 KB	-rw-r--r--
idle.html	77.18 KB	-rw-r--r--
imaplib.html	87.08 KB	-rw-r--r--
imghdr.html	17.94 KB	-rw-r--r--
imp.html	54.32 KB	-rw-r--r--
importlib.html	239.96 KB	-rw-r--r--
importlib.metadata.html	43.14 KB	-rw-r--r--
index.html	75.06 KB	-rw-r--r--
inspect.html	168.74 KB	-rw-r--r--
internet.html	29.89 KB	-rw-r--r--
intro.html	13.81 KB	-rw-r--r--
io.html	154.15 KB	-rw-r--r--
ipaddress.html	137.75 KB	-rw-r--r--
ipc.html	12.6 KB	-rw-r--r--
itertools.html	153.27 KB	-rw-r--r--
json.html	98.9 KB	-rw-r--r--
keyword.html	14.88 KB	-rw-r--r--
language.html	16.71 KB	-rw-r--r--
linecache.html	18.09 KB	-rw-r--r--
locale.html	77.35 KB	-rw-r--r--
logging.config.html	100.3 KB	-rw-r--r--
logging.handlers.html	146.28 KB	-rw-r--r--
logging.html	169.67 KB	-rw-r--r--
lzma.html	66.89 KB	-rw-r--r--
mailbox.html	176.34 KB	-rw-r--r--
mailcap.html	20.86 KB	-rw-r--r--
markup.html	22.31 KB	-rw-r--r--
marshal.html	24.43 KB	-rw-r--r--
math.html	85.82 KB	-rw-r--r--
mimetypes.html	40.27 KB	-rw-r--r--
mm.html	11.16 KB	-rw-r--r--
mmap.html	55.53 KB	-rw-r--r--
modulefinder.html	23.67 KB	-rw-r--r--
modules.html	15.88 KB	-rw-r--r--
msilib.html	78.38 KB	-rw-r--r--
msvcrt.html	29.22 KB	-rw-r--r--
multiprocessing.html	405.24 KB	-rw-r--r--
multiprocessing.shared_memory....	60 KB	-rw-r--r--
netdata.html	20.24 KB	-rw-r--r--
netrc.html	20.39 KB	-rw-r--r--
nis.html	16.76 KB	-rw-r--r--
nntplib.html	84.93 KB	-rw-r--r--
numbers.html	45.67 KB	-rw-r--r--
numeric.html	19.29 KB	-rw-r--r--
operator.html	107.32 KB	-rw-r--r--
optparse.html	256.96 KB	-rw-r--r--
os.html	594.39 KB	-rw-r--r--
os.path.html	65.54 KB	-rw-r--r--
ossaudiodev.html	56.35 KB	-rw-r--r--
pathlib.html	170.01 KB	-rw-r--r--
pdb.html	68.67 KB	-rw-r--r--
persistence.html	19.13 KB	-rw-r--r--
pickle.html	154.45 KB	-rw-r--r--
pickletools.html	22.92 KB	-rw-r--r--
pipes.html	21.7 KB	-rw-r--r--
pkgutil.html	42.76 KB	-rw-r--r--
platform.html	45.08 KB	-rw-r--r--
plistlib.html	30.06 KB	-rw-r--r--
poplib.html	41.42 KB	-rw-r--r--
posix.html	20.96 KB	-rw-r--r--
pprint.html	55.35 KB	-rw-r--r--
profile.html	84.63 KB	-rw-r--r--
pty.html	23.7 KB	-rw-r--r--
pwd.html	16.84 KB	-rw-r--r--
py_compile.html	29 KB	-rw-r--r--
pyclbr.html	24.06 KB	-rw-r--r--
pydoc.html	19.59 KB	-rw-r--r--
pyexpat.html	104.38 KB	-rw-r--r--
python.html	22.46 KB	-rw-r--r--
queue.html	43.39 KB	-rw-r--r--
quopri.html	18.64 KB	-rw-r--r--
random.html	86.31 KB	-rw-r--r--
re.html	214.24 KB	-rw-r--r--
readline.html	50.19 KB	-rw-r--r--
reprlib.html	30.85 KB	-rw-r--r--
resource.html	48.26 KB	-rw-r--r--
rlcompleter.html	18.06 KB	-rw-r--r--
runpy.html	30.99 KB	-rw-r--r--
sched.html	27.04 KB	-rw-r--r--
secrets.html	30.2 KB	-rw-r--r--
security_warnings.html	16.21 KB	-rw-r--r--
select.html	74.58 KB	-rw-r--r--
selectors.html	41.91 KB	-rw-r--r--
shelve.html	36.54 KB	-rw-r--r--
shlex.html	61.03 KB	-rw-r--r--
shutil.html	100.13 KB	-rw-r--r--
signal.html	95.39 KB	-rw-r--r--
site.html	38.16 KB	-rw-r--r--
smtpd.html	44.09 KB	-rw-r--r--
smtplib.html	81.4 KB	-rw-r--r--
sndhdr.html	16.4 KB	-rw-r--r--
socket.html	256.95 KB	-rw-r--r--
socketserver.html	91.95 KB	-rw-r--r--
spwd.html	16.71 KB	-rw-r--r--
sqlite3.html	225.51 KB	-rw-r--r--
ssl.html	328.83 KB	-rw-r--r--
stat.html	57.79 KB	-rw-r--r--
statistics.html	123.22 KB	-rw-r--r--
stdtypes.html	615.43 KB	-rw-r--r--
string.html	108.03 KB	-rw-r--r--
stringprep.html	24.94 KB	-rw-r--r--
struct.html	70.58 KB	-rw-r--r--
subprocess.html	199.03 KB	-rw-r--r--
sunau.html	39.84 KB	-rw-r--r--
superseded.html	26.21 KB	-rw-r--r--
symtable.html	33.26 KB	-rw-r--r--
sys.html	198.83 KB	-rw-r--r--
sysconfig.html	39.81 KB	-rw-r--r--
syslog.html	27.36 KB	-rw-r--r--
tabnanny.html	16.18 KB	-rw-r--r--
tarfile.html	161.92 KB	-rw-r--r--
telnetlib.html	38.21 KB	-rw-r--r--
tempfile.html	58.39 KB	-rw-r--r--
termios.html	22.86 KB	-rw-r--r--
test.html	222.85 KB	-rw-r--r--
text.html	16.8 KB	-rw-r--r--
textwrap.html	48.83 KB	-rw-r--r--
threading.html	128.33 KB	-rw-r--r--
time.html	107.46 KB	-rw-r--r--
timeit.html	52.63 KB	-rw-r--r--
tk.html	28.08 KB	-rw-r--r--
tkinter.colorchooser.html	14.49 KB	-rw-r--r--
tkinter.dnd.html	17.09 KB	-rw-r--r--
tkinter.font.html	22.21 KB	-rw-r--r--
tkinter.html	106.85 KB	-rw-r--r--
tkinter.messagebox.html	20.09 KB	-rw-r--r--
tkinter.scrolledtext.html	14.52 KB	-rw-r--r--
tkinter.tix.html	59.69 KB	-rw-r--r--
tkinter.ttk.html	138.37 KB	-rw-r--r--
token.html	45.73 KB	-rw-r--r--
tokenize.html	39.86 KB	-rw-r--r--
trace.html	38.85 KB	-rw-r--r--
traceback.html	75.61 KB	-rw-r--r--
tracemalloc.html	122.33 KB	-rw-r--r--
tty.html	14.46 KB	-rw-r--r--
turtle.html	271.71 KB	-rw-r--r--
types.html	64.85 KB	-rw-r--r--
typing.html	315.69 KB	-rw-r--r--
unicodedata.html	27.3 KB	-rw-r--r--
unittest.html	310.01 KB	-rw-r--r--
unittest.mock-examples.html	177.75 KB	-rw-r--r--
unittest.mock.html	363.51 KB	-rw-r--r--
unix.html	13.46 KB	-rw-r--r--
urllib.error.html	18.56 KB	-rw-r--r--
urllib.html	12.92 KB	-rw-r--r--
urllib.parse.html	104.65 KB	-rw-r--r--
urllib.request.html	208.87 KB	-rw-r--r--
urllib.robotparser.html	22.63 KB	-rw-r--r--
uu.html	18.2 KB	-rw-r--r--
uuid.html	42.88 KB	-rw-r--r--
venv.html	90.43 KB	-rw-r--r--
warnings.html	69.13 KB	-rw-r--r--
wave.html	36.12 KB	-rw-r--r--
weakref.html	73.36 KB	-rw-r--r--
webbrowser.html	33.98 KB	-rw-r--r--
windows.html	12.32 KB	-rw-r--r--
winreg.html	89.48 KB	-rw-r--r--
winsound.html	26.3 KB	-rw-r--r--
wsgiref.html	111.52 KB	-rw-r--r--
xdrlib.html	42.07 KB	-rw-r--r--
xml.dom.html	114.66 KB	-rw-r--r--
xml.dom.minidom.html	49.6 KB	-rw-r--r--
xml.dom.pulldom.html	30.06 KB	-rw-r--r--
xml.etree.elementtree.html	186.49 KB	-rw-r--r--
xml.html	22.34 KB	-rw-r--r--
xml.sax.handler.html	55.78 KB	-rw-r--r--
xml.sax.html	31.74 KB	-rw-r--r--
xml.sax.reader.html	56.23 KB	-rw-r--r--
xml.sax.utils.html	22.28 KB	-rw-r--r--
xmlrpc.client.html	79.73 KB	-rw-r--r--
xmlrpc.html	11.9 KB	-rw-r--r--
xmlrpc.server.html	63.56 KB	-rw-r--r--
zipapp.html	52.45 KB	-rw-r--r--
zipfile.html	116.59 KB	-rw-r--r--
zipimport.html	33.76 KB	-rw-r--r--
zlib.html	42.29 KB	-rw-r--r--
zoneinfo.html	57.25 KB	-rw-r--r--

Code Editor : zlib.html

<!DOCTYPE html>

<title>zlib — Compression compatible with gzip &#8212; Python 3.10.12 documentation</title><meta name="viewport" content="width=device-width, initial-scale=1.0">
 
 <link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
 <link rel="stylesheet" type="text/css" href="../_static/pydoctheme.css?2022.1" />
 
 <script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script>
 <script src="../_static/jquery.js"></script>
 <script src="../_static/underscore.js"></script>
 <script src="../_static/doctools.js"></script>
 
 <script src="../_static/sidebar.js"></script>
 
 <link rel="search" type="application/opensearchdescription+xml"
 title="Search within Python 3.10.12 documentation"
 href="../_static/opensearch.xml"/>
 <link rel="author" title="About these documents" href="../about.html" />
 <link rel="index" title="Index" href="../genindex.html" />
 <link rel="search" title="Search" href="../search.html" />
 <link rel="copyright" title="Copyright" href="../copyright.html" />
 <link rel="next" title="gzip — Support for gzip files" href="gzip.html" />
 <link rel="prev" title="Data Compression and Archiving" href="archiving.html" />
 <link rel="canonical" href="file:///usr/share/doc/python3.10/html/library/zlib.html" />

</head>
<body>
<div class="mobile-nav">
 <input type="checkbox" id="menuToggler" class="toggler__input" aria-controls="navigation"
 aria-pressed="false" aria-expanded="false" role="button" aria-label="Menu" />
 <label for="menuToggler" class="toggler__label">
 
 </label>
 <nav class="nav-content" role="navigation">
 <a href="https://www.python.org/" class="nav-logo">
 <img src="../_static/py.svg" alt="Logo"/>
 </a>
 <div class="version_switcher_placeholder"></div>
 <form role="search" class="search" action="../search.html" method="get">
 <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" class="search-icon">
 <path fill-rule="nonzero"
 d="M15.5 14h-.79l-.28-.27a6.5 6.5 0 001.48-5.34c-.47-2.78-2.79-5-5.59-5.34a6.505 6.505 0 00-7.27 7.27c.34 2.8 2.56 5.12 5.34 5.59a6.5 6.5 0 005.34-1.48l.27.28v.79l4.25 4.25c.41.41 1.08.41 1.49 0 .41-.41.41-1.08 0-1.49L15.5 14zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z" fill="#444"></path>
 </svg>
 <input type="text" name="q" aria-label="Quick search"/>
 <input type="submit" value="Go"/>
 </form>
 </nav>
 <div class="menu-wrapper">
 <nav class="menu" role="navigation" aria-label="main navigation">
 <div class="language_switcher_placeholder"></div>
 <h4>Previous topic</h4>
 <a href="archiving.html"
 title="previous chapter">Data Compression and Archiving</a>
 <h4>Next topic</h4>
 <a href="gzip.html"
 title="next chapter"><code class="xref py py-mod docutils literal notranslate">gzip</code> — Support for gzip files</a>
 <div role="note" aria-label="source link">
 <h3>This Page</h3>
 <ul class="this-page-menu">
 <li><a href="../bugs.html">Report a Bug</a></li>
 <li>
 <a href="https://github.com/python/cpython/blob/3.10/Doc/library/zlib.rst"
 rel="nofollow">Show Source
 </a>
 </li>
 </ul>
 </div>
 </nav>
 </div>
</div>

<div class="related" role="navigation" aria-label="related navigation">
 <h3>Navigation</h3>
 <ul>
 <li class="right" style="margin-right: 10px">
 <a href="../genindex.html" title="General Index"
 accesskey="I">index</a></li>
 <li class="right" >
 <a href="../py-modindex.html" title="Python Module Index"
 >modules</a> |</li>
 <li class="right" >
 <a href="gzip.html" title="gzip — Support for gzip files"
 accesskey="N">next</a> |</li>
 <li class="right" >
 <a href="archiving.html" title="Data Compression and Archiving"
 accesskey="P">previous</a> |</li>

<li><img src="../_static/py.svg" alt="python logo" style="vertical-align: middle; margin-top: -1px"/></li>
 <li><a href="https://www.python.org/">Python</a> &#187;</li>
 <li class="switchers">
 <div class="language_switcher_placeholder"></div>
 <div class="version_switcher_placeholder"></div>
 </li>
 <li>
 
 </li>
 <li id="cpython-language-and-version">
 <a href="../index.html">3.10.12 Documentation</a> &#187;
 </li>

<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> &#187;</li>
 <li class="nav-item nav-item-2"><a href="archiving.html" accesskey="U">Data Compression and Archiving</a> &#187;</li>
 <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate">zlib</code> — Compression compatible with gzip</a></li>
 <li class="right">

<div class="document">
 <div class="documentwrapper">
 <div class="bodywrapper">
 <div class="body" role="main">
 
 <section id="module-zlib">
<h1><a class="reference internal" href="#module-zlib" title="zlib: Low-level interface to compression and decompression routines compatible with gzip."><code class="xref py py-mod docutils literal notranslate">zlib</code></a> — Compression compatible with gzip<a class="headerlink" href="#module-zlib" title="Permalink to this headline">¶</a></h1>
<hr class="docutils" />
For applications that require data compression, the functions in this module
allow compression and decompression, using the zlib library. The zlib library
has its own home page at <a class="reference external" href="https://www.zlib.net">https://www.zlib.net</a>. There are known
incompatibilities between the Python module and versions of the zlib library
earlier than 1.1.3; 1.1.3 has a <a class="reference external" href="https://zlib.net/zlib_faq.html#faq33">security vulnerability</a>, so we recommend using
1.1.4 or later.
zlib’s functions have many options and often need to be used in a particular
order. This documentation doesn’t attempt to cover all of the permutations;
consult the zlib manual at <a class="reference external" href="http://www.zlib.net/manual.html">http://www.zlib.net/manual.html</a> for authoritative
information.
For reading and writing <code class="docutils literal notranslate">.gz</code> files see the <a class="reference internal" href="gzip.html#module-gzip" title="gzip: Interfaces for gzip compression and decompression using file objects."><code class="xref py py-mod docutils literal notranslate">gzip</code></a> module.
The available exception and functions in this module are:
<dl class="py exception">
<dt class="sig sig-object py" id="zlib.error">
exception zlib.error<a class="headerlink" href="#zlib.error" title="Permalink to this definition">¶</a></dt>
<dd>Exception raised on compression and decompression errors.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.adler32">
zlib.adler32(data[, value])<a class="headerlink" href="#zlib.adler32" title="Permalink to this definition">¶</a></dt>
<dd>Computes an Adler-32 checksum of data. (An Adler-32 checksum is almost as
reliable as a CRC32 but can be computed much more quickly.) The result
is an unsigned 32-bit integer. If value is present, it is used as
the starting value of the checksum; otherwise, a default value of 1
is used. Passing in value allows computing a running checksum over the
concatenation of several inputs. The algorithm is not cryptographically
strong, and should not be used for authentication or digital signatures. Since
the algorithm is designed for use as a checksum algorithm, it is not suitable
for use as a general hash algorithm.
<div class="versionchanged">
Changed in version 3.0: The result is always unsigned.
To generate the same numeric value when using Python 2 or earlier,
use <code class="docutils literal notranslate">adler32(data) &amp; 0xffffffff</code>.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.compress">
zlib.compress(data, /, level=- 1)<a class="headerlink" href="#zlib.compress" title="Permalink to this definition">¶</a></dt>
<dd>Compresses the bytes in data, returning a bytes object containing compressed data.
level is an integer from <code class="docutils literal notranslate">0</code> to <code class="docutils literal notranslate">9</code> or <code class="docutils literal notranslate">-1</code> controlling the level of compression;
<code class="docutils literal notranslate">1</code> (Z_BEST_SPEED) is fastest and produces the least compression, <code class="docutils literal notranslate">9</code> (Z_BEST_COMPRESSION)
is slowest and produces the most. <code class="docutils literal notranslate">0</code> (Z_NO_COMPRESSION) is no compression.
The default value is <code class="docutils literal notranslate">-1</code> (Z_DEFAULT_COMPRESSION). Z_DEFAULT_COMPRESSION represents a default
compromise between speed and compression (currently equivalent to level 6).
Raises the <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate">error</code></a> exception if any error occurs.
<div class="versionchanged">
Changed in version 3.6: level can now be used as a keyword parameter.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.compressobj">
zlib.compressobj(level=-1, method=DEFLATED, wbits=MAX_WBITS, memLevel=DEF_MEM_LEVEL, strategy=Z_DEFAULT_STRATEGY[, zdict])<a class="headerlink" href="#zlib.compressobj" title="Permalink to this definition">¶</a></dt>
<dd>Returns a compression object, to be used for compressing data streams that won’t
fit into memory at once.
level is the compression level – an integer from <code class="docutils literal notranslate">0</code> to <code class="docutils literal notranslate">9</code> or <code class="docutils literal notranslate">-1</code>.
A value of <code class="docutils literal notranslate">1</code> (Z_BEST_SPEED) is fastest and produces the least compression,
while a value of <code class="docutils literal notranslate">9</code> (Z_BEST_COMPRESSION) is slowest and produces the most.
<code class="docutils literal notranslate">0</code> (Z_NO_COMPRESSION) is no compression. The default value is <code class="docutils literal notranslate">-1</code> (Z_DEFAULT_COMPRESSION).
Z_DEFAULT_COMPRESSION represents a default compromise between speed and compression
(currently equivalent to level 6).
method is the compression algorithm. Currently, the only supported value is
<code class="xref py py-const docutils literal notranslate">DEFLATED</code>.
The wbits argument controls the size of the history buffer (or the
“window size”) used when compressing data, and whether a header and
trailer is included in the output. It can take several ranges of values,
defaulting to <code class="docutils literal notranslate">15</code> (MAX_WBITS):
<ul class="simple">
<li>+9 to +15: The base-two logarithm of the window size, which
therefore ranges between 512 and 32768. Larger values produce
better compression at the expense of greater memory usage. The
resulting output will include a zlib-specific header and trailer.</li>
<li>−9 to −15: Uses the absolute value of wbits as the
window size logarithm, while producing a raw output stream with no
header or trailing checksum.</li>
<li>+25 to +31 = 16 + (9 to 15): Uses the low 4 bits of the value as the
window size logarithm, while including a basic gzip header
and trailing checksum in the output.</li>
</ul>
The memLevel argument controls the amount of memory used for the
internal compression state. Valid values range from <code class="docutils literal notranslate">1</code> to <code class="docutils literal notranslate">9</code>.
Higher values use more memory, but are faster and produce smaller output.
strategy is used to tune the compression algorithm. Possible values are
<code class="xref py py-const docutils literal notranslate">Z_DEFAULT_STRATEGY</code>, <code class="xref py py-const docutils literal notranslate">Z_FILTERED</code>, <code class="xref py py-const docutils literal notranslate">Z_HUFFMAN_ONLY</code>,
<code class="xref py py-const docutils literal notranslate">Z_RLE</code> (zlib 1.2.0.1) and <code class="xref py py-const docutils literal notranslate">Z_FIXED</code> (zlib 1.2.2.2).
zdict is a predefined compression dictionary. This is a sequence of bytes
(such as a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object) containing subsequences that are expected
to occur frequently in the data that is to be compressed. Those subsequences
that are expected to be most common should come at the end of the dictionary.
<div class="versionchanged">
Changed in version 3.3: Added the zdict parameter and keyword argument support.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.crc32">
zlib.crc32(data[, value])<a class="headerlink" href="#zlib.crc32" title="Permalink to this definition">¶</a></dt>
<dd>Computes a CRC (Cyclic Redundancy Check) checksum of data. The
result is an unsigned 32-bit integer. If value is present, it is used
as the starting value of the checksum; otherwise, a default value of 0
is used. Passing in value allows computing a running checksum over the
concatenation of several inputs. The algorithm is not cryptographically
strong, and should not be used for authentication or digital signatures. Since
the algorithm is designed for use as a checksum algorithm, it is not suitable
for use as a general hash algorithm.
<div class="versionchanged">
Changed in version 3.0: The result is always unsigned.
To generate the same numeric value when using Python 2 or earlier,
use <code class="docutils literal notranslate">crc32(data) &amp; 0xffffffff</code>.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.decompress">
zlib.decompress(data, /, wbits=MAX_WBITS, bufsize=DEF_BUF_SIZE)<a class="headerlink" href="#zlib.decompress" title="Permalink to this definition">¶</a></dt>
<dd>Decompresses the bytes in data, returning a bytes object containing the
uncompressed data. The wbits parameter depends on
the format of data, and is discussed further below.
If bufsize is given, it is used as the initial size of the output
buffer. Raises the <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate">error</code></a> exception if any error occurs.
The wbits parameter controls the size of the history buffer
(or “window size”), and what header and trailer format is expected.
It is similar to the parameter for <a class="reference internal" href="#zlib.compressobj" title="zlib.compressobj"><code class="xref py py-func docutils literal notranslate">compressobj()</code></a>, but accepts
more ranges of values:
<ul class="simple">
<li>+8 to +15: The base-two logarithm of the window size. The input
must include a zlib header and trailer.</li>
<li>0: Automatically determine the window size from the zlib header.
Only supported since zlib 1.2.3.5.</li>
<li>−8 to −15: Uses the absolute value of wbits as the window size
logarithm. The input must be a raw stream with no header or trailer.</li>
<li>+24 to +31 = 16 + (8 to 15): Uses the low 4 bits of the value as
the window size logarithm. The input must include a gzip header and
trailer.</li>
<li>+40 to +47 = 32 + (8 to 15): Uses the low 4 bits of the value as
the window size logarithm, and automatically accepts either
the zlib or gzip format.</li>
</ul>
When decompressing a stream, the window size must not be smaller
than the size originally used to compress the stream; using a too-small
value may result in an <a class="reference internal" href="#zlib.error" title="zlib.error"><code class="xref py py-exc docutils literal notranslate">error</code></a> exception. The default wbits value
corresponds to the largest window size and requires a zlib header and
trailer to be included.
bufsize is the initial size of the buffer used to hold decompressed data. If
more space is required, the buffer size will be increased as needed, so you
don’t have to get this value exactly right; tuning it will only save a few calls
to <code class="xref c c-func docutils literal notranslate">malloc()</code>.
<div class="versionchanged">
Changed in version 3.6: wbits and bufsize can be used as keyword arguments.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="zlib.decompressobj">
zlib.decompressobj(wbits=MAX_WBITS[, zdict])<a class="headerlink" href="#zlib.decompressobj" title="Permalink to this definition">¶</a></dt>
<dd>Returns a decompression object, to be used for decompressing data streams that
won’t fit into memory at once.
The wbits parameter controls the size of the history buffer (or the
“window size”), and what header and trailer format is expected. It has
the same meaning as <a class="reference external" href="#decompress-wbits">described for decompress()</a>.
The zdict parameter specifies a predefined compression dictionary. If
provided, this must be the same dictionary as was used by the compressor that
produced the data that is to be decompressed.
<div class="admonition note">
Note
If zdict is a mutable object (such as a <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate">bytearray</code></a>), you must not
modify its contents between the call to <a class="reference internal" href="#zlib.decompressobj" title="zlib.decompressobj"><code class="xref py py-func docutils literal notranslate">decompressobj()</code></a> and the first
call to the decompressor’s <code class="docutils literal notranslate">decompress()</code> method.
</div>
<div class="versionchanged">
Changed in version 3.3: Added the zdict parameter.
</div>
</dd></dl>

Compression objects support the following methods:
<dl class="py method">
<dt class="sig sig-object py" id="zlib.Compress.compress">
Compress.compress(data)<a class="headerlink" href="#zlib.Compress.compress" title="Permalink to this definition">¶</a></dt>
<dd>Compress data, returning a bytes object containing compressed data for at least
part of the data in data. This data should be concatenated to the output
produced by any preceding calls to the <a class="reference internal" href="#zlib.compress" title="zlib.compress"><code class="xref py py-meth docutils literal notranslate">compress()</code></a> method. Some input may
be kept in internal buffers for later processing.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="zlib.Compress.flush">
Compress.flush([mode])<a class="headerlink" href="#zlib.Compress.flush" title="Permalink to this definition">¶</a></dt>
<dd>All pending input is processed, and a bytes object containing the remaining compressed
output is returned. mode can be selected from the constants
<code class="xref py py-const docutils literal notranslate">Z_NO_FLUSH</code>, <code class="xref py py-const docutils literal notranslate">Z_PARTIAL_FLUSH</code>, <code class="xref py py-const docutils literal notranslate">Z_SYNC_FLUSH</code>,
<code class="xref py py-const docutils literal notranslate">Z_FULL_FLUSH</code>, <code class="xref py py-const docutils literal notranslate">Z_BLOCK</code> (zlib 1.2.3.4), or <code class="xref py py-const docutils literal notranslate">Z_FINISH</code>,
defaulting to <code class="xref py py-const docutils literal notranslate">Z_FINISH</code>. Except <code class="xref py py-const docutils literal notranslate">Z_FINISH</code>, all constants
allow compressing further bytestrings of data, while <code class="xref py py-const docutils literal notranslate">Z_FINISH</code> finishes the
compressed stream and prevents compressing any more data. After calling <a class="reference internal" href="#zlib.Compress.flush" title="zlib.Compress.flush"><code class="xref py py-meth docutils literal notranslate">flush()</code></a>
with mode set to <code class="xref py py-const docutils literal notranslate">Z_FINISH</code>, the <a class="reference internal" href="#zlib.compress" title="zlib.compress"><code class="xref py py-meth docutils literal notranslate">compress()</code></a> method cannot be called again;
the only realistic action is to delete the object.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="zlib.Compress.copy">
Compress.copy()<a class="headerlink" href="#zlib.Compress.copy" title="Permalink to this definition">¶</a></dt>
<dd>Returns a copy of the compression object. This can be used to efficiently
compress a set of data that share a common initial prefix.
</dd></dl>

<div class="versionchanged">
Changed in version 3.8: Added <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate">copy.copy()</code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate">copy.deepcopy()</code></a> support to compression
objects.
</div>
Decompression objects support the following methods and attributes:
<dl class="py attribute">
<dt class="sig sig-object py" id="zlib.Decompress.unused_data">
Decompress.unused_data<a class="headerlink" href="#zlib.Decompress.unused_data" title="Permalink to this definition">¶</a></dt>
<dd>A bytes object which contains any bytes past the end of the compressed data. That is,
this remains <code class="docutils literal notranslate">b&quot;&quot;</code> until the last byte that contains compression data is
available. If the whole bytestring turned out to contain compressed data, this is
<code class="docutils literal notranslate">b&quot;&quot;</code>, an empty bytes object.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="zlib.Decompress.unconsumed_tail">
Decompress.unconsumed_tail<a class="headerlink" href="#zlib.Decompress.unconsumed_tail" title="Permalink to this definition">¶</a></dt>
<dd>A bytes object that contains any data that was not consumed by the last
<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> call because it exceeded the limit for the uncompressed data
buffer. This data has not yet been seen by the zlib machinery, so you must feed
it (possibly with further data concatenated to it) back to a subsequent
<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> method call in order to get correct output.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="zlib.Decompress.eof">
Decompress.eof<a class="headerlink" href="#zlib.Decompress.eof" title="Permalink to this definition">¶</a></dt>
<dd>A boolean indicating whether the end of the compressed data stream has been
reached.
This makes it possible to distinguish between a properly formed compressed
stream, and an incomplete or truncated one.
<div class="versionadded">
New in version 3.3.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="zlib.Decompress.decompress">
Decompress.decompress(data, max_length=0)<a class="headerlink" href="#zlib.Decompress.decompress" title="Permalink to this definition">¶</a></dt>
<dd>Decompress data, returning a bytes object containing the uncompressed data
corresponding to at least part of the data in string. This data should be
concatenated to the output produced by any preceding calls to the
<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> method. Some of the input data may be preserved in internal
buffers for later processing.
If the optional parameter max_length is non-zero then the return value will be
no longer than max_length. This may mean that not all of the compressed input
can be processed; and unconsumed data will be stored in the attribute
<a class="reference internal" href="#zlib.Decompress.unconsumed_tail" title="zlib.Decompress.unconsumed_tail"><code class="xref py py-attr docutils literal notranslate">unconsumed_tail</code></a>. This bytestring must be passed to a subsequent call to
<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> if decompression is to continue. If max_length is zero
then the whole input is decompressed, and <a class="reference internal" href="#zlib.Decompress.unconsumed_tail" title="zlib.Decompress.unconsumed_tail"><code class="xref py py-attr docutils literal notranslate">unconsumed_tail</code></a> is empty.
<div class="versionchanged">
Changed in version 3.6: max_length can be used as a keyword argument.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="zlib.Decompress.flush">
Decompress.flush([length])<a class="headerlink" href="#zlib.Decompress.flush" title="Permalink to this definition">¶</a></dt>
<dd>All pending input is processed, and a bytes object containing the remaining
uncompressed output is returned. After calling <a class="reference internal" href="#zlib.Decompress.flush" title="zlib.Decompress.flush"><code class="xref py py-meth docutils literal notranslate">flush()</code></a>, the
<a class="reference internal" href="#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate">decompress()</code></a> method cannot be called again; the only realistic action is
to delete the object.
The optional parameter length sets the initial size of the output buffer.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="zlib.Decompress.copy">
Decompress.copy()<a class="headerlink" href="#zlib.Decompress.copy" title="Permalink to this definition">¶</a></dt>
<dd>Returns a copy of the decompression object. This can be used to save the state
of the decompressor midway through the data stream in order to speed up random
seeks into the stream at a future point.
</dd></dl>

<div class="versionchanged">
Changed in version 3.8: Added <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate">copy.copy()</code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate">copy.deepcopy()</code></a> support to decompression
objects.
</div>
Information about the version of the zlib library in use is available through
the following constants:
<dl class="py data">
<dt class="sig sig-object py" id="zlib.ZLIB_VERSION">
zlib.ZLIB_VERSION<a class="headerlink" href="#zlib.ZLIB_VERSION" title="Permalink to this definition">¶</a></dt>
<dd>The version string of the zlib library that was used for building the module.
This may be different from the zlib library actually used at runtime, which
is available as <a class="reference internal" href="#zlib.ZLIB_RUNTIME_VERSION" title="zlib.ZLIB_RUNTIME_VERSION"><code class="xref py py-const docutils literal notranslate">ZLIB_RUNTIME_VERSION</code></a>.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="zlib.ZLIB_RUNTIME_VERSION">
zlib.ZLIB_RUNTIME_VERSION<a class="headerlink" href="#zlib.ZLIB_RUNTIME_VERSION" title="Permalink to this definition">¶</a></dt>
<dd>The version string of the zlib library actually loaded by the interpreter.
<div class="versionadded">
New in version 3.3.
</div>
</dd></dl>

<div class="admonition seealso">
See also
<dl class="simple">
<dt>Module <a class="reference internal" href="gzip.html#module-gzip" title="gzip: Interfaces for gzip compression and decompression using file objects."><code class="xref py py-mod docutils literal notranslate">gzip</code></a></dt><dd>Reading and writing gzip-format files.
</dd>
<dt><a class="reference external" href="http://www.zlib.net">http://www.zlib.net</a></dt><dd>The zlib library home page.
</dd>
<dt><a class="reference external" href="http://www.zlib.net/manual.html">http://www.zlib.net/manual.html</a></dt><dd>The zlib manual explains the semantics and usage of the library’s many
functions.
</dd>
</dl>
</div>
</section>

<div class="clearer"></div>
 </div>
 </div>
 </div>
 <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
 <div class="sphinxsidebarwrapper">
 <h4>Previous topic</h4>
 <a href="archiving.html"
 title="previous chapter">Data Compression and Archiving</a>
 <h4>Next topic</h4>
 <a href="gzip.html"
 title="next chapter"><code class="xref py py-mod docutils literal notranslate">gzip</code> — Support for gzip files</a>
 <div role="note" aria-label="source link">
 <h3>This Page</h3>
 <ul class="this-page-menu">
 <li><a href="../bugs.html">Report a Bug</a></li>
 <li>
 <a href="https://github.com/python/cpython/blob/3.10/Doc/library/zlib.rst"
 rel="nofollow">Show Source
 </a>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="clearer"></div>
 </div> 
 <div class="related" role="navigation" aria-label="related navigation">
 <h3>Navigation</h3>
 <ul>
 <li class="right" style="margin-right: 10px">
 <a href="../genindex.html" title="General Index"
 >index</a></li>
 <li class="right" >
 <a href="../py-modindex.html" title="Python Module Index"
 >modules</a> |</li>
 <li class="right" >
 <a href="gzip.html" title="gzip — Support for gzip files"
 >next</a> |</li>
 <li class="right" >
 <a href="archiving.html" title="Data Compression and Archiving"
 >previous</a> |</li>

<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> &#187;</li>
 <li class="nav-item nav-item-2"><a href="archiving.html" >Data Compression and Archiving</a> &#187;</li>
 <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate">zlib</code> — Compression compatible with gzip</a></li>
 <li class="right">

<div class="inline-search" role="search">
 <form class="inline-search" action="../search.html" method="get">
 <input placeholder="Quick search" aria-label="Quick search" type="text" name="q" />
 <input type="submit" value="Go" />
 <input type="hidden" name="check_keywords" value="yes" />
 <input type="hidden" name="area" value="default" />
 </form>
 </div>
 |
 </li>
 
 </ul>
 </div> 
 <div class="footer">
 &copy; <a href="../copyright.html">Copyright</a> 2001-2026, Python Software Foundation.
 
 This page is licensed under the Python Software Foundation License Version 2.
 
 Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.
 
 See <a href="/license.html">History and License</a> for more information.

The Python Software Foundation is a non-profit corporation.
<a href="https://www.python.org/psf/donations/">Please donate.</a>

Last updated on January 26, 2026.
 <a href="/bugs.html">Found a bug</a>?

Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 4.3.2.
 </div>

</body>
</html>

${this.title}

Code Editor : zlib.html