concatenating strings with + operator

[CarlaRogersWI]

Hello,

The purpose of this post is to request either verification or correction of python programming rules for concatenating strings using a + operator. I have been unable to find documentation on how the + operator works.

I found the + operator mentioned in a brief blog explanation on how to connect strings together in python. The explanation included code sample where a + operator was used to connect two smaller strings into a larger string. I ran into a problem when I tried following the example. the problem seemed to be resolved when i changed

dittle="2010-01-07 06:56:00+00:00" most_recent = dittle[:10]+"T"+dittle[:12-6]

The only thing I got from that was error messages saying I was using space and indents wrong.

The problem seemed to be eliminated by replacing inserting space bvefore and after the + operators

dittle="2010-01-07 06:56:00+00:00" most_recent = dittle[:10] + "T" + dittle[:12-6]

Sanity check is: does python require spaces on both sides of the + operator, when + is concatenating strings?

string_a = "abc" string_b = "xyz"

To concatenate those two,

concat_string = string_a + string_b

is ok, but

concat_string = string_a+ string_b concat_string = string_a +string_b concat_string = string_a+ tring_b

All those will fail?

Is a python programming manual where I could find this rule explained?

Any information you can provide will be appreciated immensely.

deanhystad write Aug-09-2025, 01:21 PM:
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[deanhystad]

All your examples run fine for me, except this:

concat_string = string_a+ tring_b

And that one failed because there is no tring_b.

What version of python are you using? How do you run your programs?

[Gribouillis]

The white space characters around the + operator are irrelevant to the Python interpreter. Write as many as you want, or none of them, the result is the same.

[snippsat]

As space characters around the + operator are irrelevant,but can soon get ugly if try to add spaces in string.
Then f-string will make cleaner.

greeting = "Hello " + first_name + " " + last_name + "!"

With f-string,both have same output.

greeting = f"Hello {first_name} {last_name}!"

Your code with f-string

>>> most_recent = dittle[:10] + "T" + dittle[:12-6] >>> most_recent '2010-01-07T2010-0' >>> >>> most_recent = f"{dittle[:10]}T{dittle[:12-6]}" >>> most_recent '2010-01-07T2010-0'

[PyRobo]

The spaces around the plus operator are a python standard, but are not required by the interpreter itself. You seem to be using a system that is running a style check before attempting to run the code itself. VSCode, PyCharm, and other IDEs are often set up this way.

Python standards for code formatting are laid out in PEP 8.

There is also the Black style formatter which will take your code and rearrange it so that it matches what it thinks is a good format. The format it targets is PEP 8 compliant but is even stricter. For example Python lets you use single quotes or double quotes around a string. Black wants only double quotes. The target style information is a good guide to writing readably formatted python even if you don't use Black.

[PyRobo]

Also you will have a problem with

dittle[:12-6]

. The 12-6 will be evaluated as 6 resulting in

dittle[:6]

which just gives you the first six characters of dittle. I think you may have intended something like

dittle[-6:]

which returns the last six characters of your string.

[noisefloor]

Hi,

generally speaking: to concatenate strings in Python with + is considered bad practice, as Python has better ways to it. Either use f-Stings for the format method of strings. Both is extensively covered in the Python documentation.

For the given problem, it is pointless anyway. You better use Python's datetime module:

>>> some_time = '2010-01-07 06:56:00+00:00' >>> from datetime import datetime >>> datetime.fromisoformat(some_time) datetime.datetime(2010, 1, 7, 6, 56, tzinfo=datetime.timezone.utc) >>> datetime.fromisoformat(some_time).isoformat() '2010-01-07T06:56:00+00:00' >>>

Regards, noisefloor