Why doesn't the + operator work between multi single line strings?

Question

I am trying to concatenate a multi line string with a single line in python and it's giving me an invalid syntax error.

 authHeader = '<header></header>'

 reqBody = '<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope">' 
                 + authHeader + 
                '''<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
                <GetSnapshotUri xmlns="http://www.onvif.org/ver10/media/wsdl"><ProfileToken>quality_h264</ProfileToken></GetSnapshotUri>
                </s:Body>
                </s:Envelope>
                '''

The problem isn't adding single-line and multi-line strings, it's that you're missing any way to tell Python that the logical line is on multiple physical lines... — jonrsharpe, May 15 '15 at 14:29
Just add `\\` at the end of each line break so Python knows to continue the statement — Cory Kramer, May 15 '15 at 14:30

James Mills · Accepted Answer · 2015-05-15T14:45:49.513

No need to use the + operator to concatenate strings you want to spread out over multiple lines for better readability. Just do something like this:

s = (
    "my very long string"
    "that spans multiple lines"
)

The parser will correctly deal with this and it is part of the Python grammar (String Literal Concatentation. Turning larger strings into sequences of code like this often ends up being far more readable.

For more info, see the Python docs on Strings which states:

This feature is particularly useful when you want to break long strings:

>>> text = ('Put several strings within parentheses '
            'to have them joined together.')
>>> text
'Put several strings within parentheses to have them joined together.'

But that doesn't work with variables, which is his case – rafaelc May 15 '15 at 14:50 — rafaelc, May 15 '15 at 14:50

Why doesn't the + operator work between multi single line strings?

1 Answers1