How to comment out a block of code in Python [duplicate]

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Is there a mechanism to comment out large blocks of Python code?

Right now, the only ways I can see of commenting out code are to either start every line with a #, or to enclose the code in triple quotes: """.

The problem with these is that inserting # before every line is cumbersome and """ makes the string I want to use as a comment show up in generated documentation.

After reading all comments, the answer seems to be "No".

Inertia answered 23/3, 2009 at 22:17 Comment(6)

This question was answered previously in Stack Overflow question Why doesn't Python have multiline comments?. – Darter 23/3, 2009 at 22:26

Additional guidelines of professional practice, "Don't use triple-quotes", distinguishes it from other posts ... – Deckle 7/1, 2015 at 22:23

Sigh. One more useful and non-duplicate question marked as duplicate... This one asks for a solution, while the other one takes the answer (namely that no, there's no solution) as a prerequisite for asking what it has to ask. – Monoclinous 8/4, 2019 at 15:53

Ctrl + / works for PyCharm – Shaving 24/4, 2020 at 8:23

<snark>Perl allows you to use the documentation syntax for block commenting in such a way that it does NOT end up in the documentation. That's why we have more than one way to do things. It's called 'flexibility'. <\snark> – Gord 29/4, 2020 at 20:10

For Jupyter, to comment use Crtl + / and uncomment use Crtl - / – Scholem 15/2, 2021 at 13:55

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Python does not have such a mechanism. Prepend a # to each line to block comment. For more information see PEP 8. Most Python IDEs support a mechanism to do the block-commenting-with-hash-signs automatically for you. For example, in IDLE on my machine, it's Alt+3 and Alt+4.

Don't use triple-quotes; as you discovered, this is for documentation strings not block comments, although it has a similar effect. If you're just commenting things out temporarily, this is fine as a temporary measure.

Goingson answered 23/3, 2009 at 22:20 Comment(22)

Geany also has this. Right click, Format, Comment Line(s). – Askance 27/10, 2011 at 2:6

For non-Americans, that's a "hash" sign. – Galloromance 31/10, 2011 at 14:36

in Notepad++ that's Ctrl+K (v.5.9.2) for any supported language – Nonflammable 3/12, 2011 at 0:50

In Eclipse, toggling comment for a selected block of code is performed using Ctrl+/. You do not need to select the code if it is only a single line. – Gaines 6/6, 2012 at 6:58

Even for Americans, "pound" should be £ or ₤. – Airedale 4/7, 2012 at 16:12

one disadvantage of mix multi-line string and block comments is IDE has no idea what you want thus can't show comment in different style as needed. – Football 17/9, 2012 at 3:58

In Vim with NERDCommentor installed, it is as easy as selecting the portion of code to be commented and pressing \c<space> – Workable 29/9, 2012 at 15:44

In PyCharm, it's CTRL-/ – Quagmire 20/2, 2013 at 16:38

You can't triple-quote code that contains triple-quotes. – Wakeen 26/6, 2013 at 22:18

Actually, that symbol is called an octothorp. Please stop using local slang terms - few Americans call it a hash, and few non-Americans call it a pound, but nobody ever refers to anything else when they say octothorp. Except the person who chooses to defy this definitive answer by using it to mean something else. – Keishakeisling 23/7, 2013 at 14:33

The creator of python actually suggests to use multi-line strings as block comments, so I would say your statement "Don't use triple-quotes" isn't appropriate. – Ber 30/10, 2013 at 19:19

@JesseWebb: He wrote that about two and a half years after this answer, though, so he changed his mind. :) – Goingson 1/11, 2013 at 15:5

From a Microsoft developer, # is a "sharp" sign – Leadership 20/12, 2013 at 22:4

@JesseWebb Although it might be noted to use triple quotes, I found a bug in python library I was using (Pyshark) with regards to Python 3. there used to be this line in a triple quote comment in the pyshark library: (i.e. \Device\NPF_..). This was ignored in Python2 and ran fine, but Python 3 threw this error: "SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 14-15: malformed \N character." Since then, I avoid triple quotes. – Turgeon 23/9, 2014 at 17:39

Ctrl+/ in PyCharm will do comment / uncomment the highlighted rows – Apostil 11/9, 2015 at 8:6

As said above, Python's creator actually suggests using triple quotes as block comments. Most editors will detect a triple-quoted string used in this way (not assigned or used in any way) and color it with the comment color. You can use ''' to comment blocks of code containing """ and vice-versa. – Tarmac 23/3, 2017 at 12:11

Calling it a hash, hash symbol, or number sign is the best bet. Especially now in 2017 hash is one of the most common ways to refer to that symbol. Nobody refers to it as an octothorpe except people trying to show off that they know that it's called an octothorpe. oxfordlearnersdictionaries.com/us/definition/english/… – Baldachin 1/11, 2017 at 20:59

It's a sharp sign for musicians.(e.g A major scale: A B C# D E F# G# A) – Chrominance 18/11, 2017 at 20:55

@johnktejik This '♯' is a sharp sign. '#' this is the number sig. – Lotus 13/3, 2018 at 12:38

The correct term is 'number sign' (Unicode U+0023). It is also indexed under 'octothorpe', 'crosshatch', 'pound sign', and 'hash'. – Chukchi 9/5, 2018 at 13:33

few Americans call it a hash, and few non-Americans call it a pound The number of Americans that call it a hash plus the number of non-Americans that call it a pound is at least 1,000 times the number of people on Earth that call it octothorpe. – Minny 15/10, 2021 at 14:24

And here this whole time I thought it was called a comment-symbol – Rutilant 18/10, 2021 at 17:7

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Hide the triple quotes in a context that won't be mistaken for a docstring, eg:

'''
...statements...
''' and None

or:

if False: '''
...statements...
'''

Epigoni answered 24/3, 2009 at 0:47 Comment(4)

I don't think that is a good advice, you are adding complexity to your code without any real benefit. Someone reading that would have to figure out why is that code there and what is it suppouse to do. – Gladis 25/5, 2012 at 15:49

What if the code you want to comment out already contains triple-quoted strings? – Wakeen 26/6, 2013 at 22:19

luckily for me it did not. – Thorma 29/10, 2013 at 18:24

@keithThompson then use the other kind of triple quoted string – Heighttopaper 16/6, 2021 at 0:57

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The only cure I know for this is a good editor. Sorry.

Mcnary answered 23/3, 2009 at 22:22 Comment(2)

Clearly, all Real Python Programmers use ed, where this problem is easily solved with: 12,31s/^/#/ – Elishaelision 23/3, 2009 at 23:49

vim with nerdcommenter. Select the block you want and ,c<space> – Bolus 10/10, 2014 at 22:37

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The only way you can do this without triple quotes is to add an:

if False:

And then indent all your code. Note that the code will still need to have proper syntax.

Many Python IDEs can add # for you on each selected line, and remove them when un-commenting too. Likewise, if you use vi or Emacs you can create a macro to do this for you for a block of code.

Lux answered 23/3, 2009 at 22:19 Comment(5)

The op mentioned that they do not want the comments to appear as doc strings. – Statesmanship 23/3, 2009 at 22:22

-1 retracted. That's a clever idea, though it may mean that the comments need comments :) – Statesmanship 23/3, 2009 at 22:49

That solution is similar to just commenting out the code, except that you add four spaces instead of # and that you also need to add "if False:" line. – Pugh 23/9, 2009 at 8:21

I was doing some script hacking and that is what I came up with. (So, +1). It's very slick that I can simply write "if False:", push the block over 1 tab and I'm done. I've used more than one editor where the method is nothing more than,highlight the block, then press tab. Strangely enough, I asked the original question for a friend, wanting to show off S.O. back when it was new. – Inertia 31/3, 2018 at 4:55

Ctrl+ / or Ctrl + Shift+/ in PyCharm does the same – Eppes 24/3, 2019 at 2:58

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In JetBrains PyCharm on Mac use Command + / to comment/uncomment selected block of code. On Windows, use CTRL + /.

Excellence answered 4/3, 2013 at 7:35 Comment(5)

This also works for PyCharm Community Edition, which is free and open-sourced. – Elsieelsinore 27/8, 2014 at 12:26

thanks! works with text wrangler as well – Hubbell 23/9, 2016 at 3:46

CTRL+/ on Windows doesn't work for a Swedish keyboard layout. – Pede 22/8, 2017 at 8:16

Also works for VSCode on macOS – Breaker 29/11, 2022 at 1:57

Also works on VSCode on Windows – Grume 9/2, 2023 at 19:27

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M-x comment-region, in Emacs' Python mode.

Gallinule answered 23/3, 2009 at 22:33 Comment(1)

M-; (comment-dwim) too – Pugh 23/9, 2009 at 8:23

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At least in VIM you can select the first column of text you want to insert using Block Visual mode (CTRL+V in non-windows VIMs) and then prepend a # before each line using this sequence:

I#<esc>

In Block Visual mode I moves to insert mode with the cursor before the block on its first line. The inserted text is copied before each line in the block.

Ostmark answered 1/10, 2009 at 21:27 Comment(0)

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In vi:

Go to top of block and mark it with letter a.
Go to bottom of block and mark it with letter b

Then do

:'a,'b s!^!#!

Sanfordsanfourd answered 16/9, 2010 at 17:48 Comment(1)

Or: CTRL+V (and select lines) => :s/^/#/g If text highlighting is bothering you => :noh – Videlicet 19/8, 2018 at 1:52

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comm='''
Junk, or working code 
that I need to comment.
'''

You can replace comm by a variable of your choice that is perhaps shorter, easy to touch-type, and you know does not (and will not) occur in your programs. Examples: xxx, oo, null, nil.

Valuate answered 7/3, 2011 at 6:12 Comment(1)

This would be loaded to memory at run time, and if the intention is to create a comment you want the program to ignore it. Leading every line with a # would be better. Also, don't assign things to a variable called null, that's just asking for disaster. – Hungry 2/1, 2021 at 23:52

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I use Notepad++ on a Windows machine, select your code, type CTRL-K. To uncomment you select code and press Ctrl + Shift + K.

Incidentally, Notepad++ works nicely as a Python editor. With auto-completion, code folding, syntax highlighting, and much more. And it's free as in speech and as in beer!

Rozanne answered 1/5, 2010 at 3:30 Comment(0)

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Yes, there is (depending on your editor). In PyDev (and in Aptana Studio with PyDev):

Ctrl + 4 - comment selected block
Ctrl + 5 - uncomment selected block

Backhanded answered 25/5, 2012 at 15:41 Comment(1)

but it is not pep8 format. – Wendling 23/12, 2016 at 10:55

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In Eclipse + PyDev, Python block commenting is similar to Eclipse Java block commenting; select the lines you want to comment and use Ctrl + / to comment. To uncomment a commented block, do the same thing.

Cysto answered 9/6, 2012 at 19:0 Comment(0)

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In Visual Studio using the Python Tools for Visual Studio, blocks can be commented out by Ctrl+K, Ctrl+C and uncommented by Ctrl+K, Ctrl+U.

Picked answered 10/1, 2013 at 20:18 Comment(2)

This works for Visual Studio Code as well. – Omora 10/1, 2018 at 23:54

On Windows for VS Code ctrl + / – Mistreat 22/11, 2019 at 11:50

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The only mechanism to comment out Python code (understood as code ignored by the interpreter) is the #.

As you say, you can also use string literals, that are not ignored by the interpreter, but can be completely irrelevant for the program execution.

Zoom answered 23/3, 2009 at 22:31 Comment(0)

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In Eclipse using PyDev, you can select a code block and press Ctrl + #.

Geostatics answered 13/2, 2013 at 3:20 Comment(2)

to uncomment a block, use ctrl+shift+# – Barbate 17/12, 2013 at 1:3

This also works in komodo-edit for python – Antitragus 19/2, 2015 at 15:52

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Triple quotes are OK to me. You can use ''' foo ''' for docstrings and """ bar """ for comments or vice-versa to make the code more readable.

Patsypatt answered 24/3, 2009 at 7:35 Comment(1)

My problem with triple quotes is that they actually are being checked for syntax. that has to be overhead that is unneeded for a comment. Case in point: if you had ''' /NPF ''' and run that in Python 3, it will throw a syntax error. So Python 3 is checking each triple quote for syntax validity. If you switch to # and comment the line, it is skipped. – Turgeon 23/9, 2014 at 18:38

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On Eric4 there is an easy way: select a block, type Ctrl+M to comment the whole block or Ctrl+alt+M to uncomment.

Geodesic answered 18/1, 2012 at 12:20 Comment(0)

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Another editor-based solution: text "rectangles" in Emacs.

Highlight the code you want to comment out, then C-x-r-t #

To un-comment the code: highlight, then C-x-r-k

I use this all-day, every day. (Assigned to hot-keys, of course.)

This and powerful regex search/replace is the reason I tolerate Emacs's other "eccentricities".

Bond answered 19/1, 2012 at 22:56 Comment(0)

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Use a nice editor like SciTe, select your code, press Ctrl + Q and done.

If you don't have an editor that supports block comments you can use a triple quoted string at the start and the end of your code block to 'effectively' comment it out. It is not the best practice though.

Motorbus answered 24/3, 2009 at 7:22 Comment(0)

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