In python print("backslash \") produces error but print("backslash \ ") doesn't produce error

Question

In python print("backslash \") produces error but print("backslash \ ") doesn't produce error.

in print(backslash \") there is no space between \ and ". and this produces a SyntaxError: EOL while scanning string literal

whereas if i give a space between the \ and " , then there in no error. Why?

few more examples

print(" this is double backslash \\\sad ")

the above statement doesn't produce any error, and it generates the output as:-

this is a single backslash \\sad

and I get the same output on writing this :-

print(" this is a single backslash \\\\sad ")

Here I have escape each \ separately, so this is working but why the previous one is working?

o sorry for that part of question..!! but what's the reason for the print of \\ ? — Amit Upadhyay, Oct 23 '15 at 13:54
First slash escapes the second one and `\s` has no special meaning, hence `\\\s` becomes `\\s`. — Ashwini Chaudhary, Oct 23 '15 at 13:56
Do you understand what backslashes in strings *actually do*? — jonrsharpe, Oct 23 '15 at 14:22
@jonrsharpe thank's for your concern, I understood what backslash does but i didn't know much backslash in strings. If you can tell then ofcourse that will help me somehow. I'm new to programming that's why facing much problems. :) — Amit Upadhyay, Oct 23 '15 at 16:21
@AmitUpadhyay then have a look at e.g. https://docs.python.org/2/reference/lexical_analysis.html#string-literals, which explains how the string literals work — jonrsharpe, Oct 23 '15 at 16:23
The problem is the same for ordinary string literals as for raw string literals, and with the same underlying cause. So this is effectively a duplicate. — Karl Knechtel, Oct 27 '22 at 20:09

Martijn Pieters · Accepted Answer · 2015-10-23T13:59:36.727

The \ character is the escape sequence character. \" escapes a quote as part of the string value, rather than a delimiter that signals the start or end of a string.

By adding a space, you produced a non-existing escape sequence, and the \ is interpreted as a literal backslash instead.

See the string literals documentation:

The backslash (\) character is used to escape characters that otherwise have a special meaning, such as newline, backslash itself, or the quote character.

A \ without a recognised escape sequence is always a plain \ however. See the documentation for recognised sequences.

Note that this also means you need to be able to escape the escape sequence; for that reason \\ produces a single backslash literal. That way you can include \\n in a string and that is interpreted as one \ character and n, while \n produces a newline character.

@AmitUpadhyay: you need a way of escaping the escape, so ``\\`` produces one backslash. `\s` is not a valid escape, so produces a ``\`` and `s`. — Martijn Pieters, Oct 23 '15 at 13:58

score 1 · Answer 2 · answered Oct 23 '15 at 13:53

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Because when you print("backslash \") you are escaping the last " so therefore you get an error.. more info on escape chars: https://docs.python.org/2/reference/lexical_analysis.html

answered Oct 23 '15 at 13:53

Leustad

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sorry for that part of question..!! but what's the reason for the print of \\ ? – Amit Upadhyay Oct 23 '15 at 13:55
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a single \ escapes the character on its right. When there is a space after '\' you are escaping the space when there is no space you are escaping " character and the first " requires the closing "... make sense? – Leustad Oct 23 '15 at 14:01

In python print("backslash \") produces error but print("backslash \ ") doesn't produce error

2 Answers2