How to Create Multiline Comments in Python

How do I create multiline comments in Python?

You can use triple-quoted strings. When they're not a docstring (the first thing in a class/function/module), they are ignored.

'''
This is a multiline
comment.
'''

(Make sure to indent the leading ''' appropriately to avoid an IndentationError.)

Guido van Rossum (creator of Python) tweeted this as a "pro tip".

However, Python's style guide, PEP8, favors using consecutive single-line comments, like this:

# This is a multiline
# comment.

...and this is also what you'll find in many projects. Text editors usually have a shortcut to do this easily.

Python multiline comments

Triple quoted strings are used as comments by many developers but it is actually not a comment. It is similar to regular strings in python but it allows the string to be multi-line. You will find no official reference for triple quoted strings to be a comment.

In python, there is only one type of comment that starts with hash # and can contain only a single line of text.

According to PEP 257, it can however be used as a docstring, which is again not really a comment.

def foo():
    """
    Developer friendly text for describing the purpose of function
    Some test cases used by different unit testing libraries
    """
   <body of the function>

You can just assign them to a variable as you do with single quoted strings:

x = """a multi-line text
enclosed by
triple quotes
"""

Furthermore, if you try it in a repl, triple quoted strings get printed, had it really been a comment, should it have been printed?:

>>> #comment
>>> """triple quoted"""
'triple quoted'

Multiple line comment in Python

Try this

'''
This is a multiline
comment. I can type here whatever I want.
'''

Python does have a multiline string/comment syntax in the sense that unless used as docstrings, multiline strings generate no bytecode -- just like #-prepended comments. In effect, it acts exactly like a comment.

On the other hand, if you say this behavior must be documented in the official docs to be a true comment syntax, then yes, you would be right to say it is not guaranteed as part of the language specification.

In any case your editor should also be able to easily comment-out a selected region (by placing a # in front of each line individually). If not, switch to an editor that does.

Programming in Python without certain text editing features can be a painful experience. Finding the right editor (and knowing how to use it) can make a big difference in how the Python programming experience is perceived.

Not only should the editor be able to comment-out selected regions, it should also be able to shift blocks of code to the left and right easily, and should automatically place the cursor at the current indentation level when you press Enter. Code folding can also be useful.

How to comment out a block of code in Python

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.

Python multiline comment doesn't work in terminal

That's because it's a multi line string literal, not a multi line comment. It can be used as a multi line comment though, because, just as a comment, it doesn't "do anything", and it seems that it's ignored, just like a comment.

However, as you observed, the string literal actually evaluates to a string object with all the newline characters and stuff. Comments, on the other hand, are ignored completely and aren't evaluated to anything.

Why doesn't Python have multiline comments?

I doubt you'll get a better answer than, "Guido didn't feel the need for multi-line comments".

Guido has tweeted about this:

Python tip: You can use multi-line strings as multi-line comments. Unless used as docstrings, they generate no code! :-)

Shortcut key for commenting out lines of Python code in Spyder

Single line comment
Ctrl + 1
Multi-line comment select the lines to be commented
Ctrl + 4
Unblock Multi-line comment
Ctrl + 5