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In the C# program that I am reading, the slashes in the pathnames are doubled, for example:

"C:\\Users\\Tim\\Download"

Why are the slashes doubled in pathnames in C# programs, and is this necessary?

TylerH
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Tim
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    It's exactly the same as in C++, your top tag. Ever thought that this could be the same? – Thomas Weller Feb 16 '17 at 22:12
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    This does not seem to be asking the same duplicate of that question @NathanFisher see http://chat.stackoverflow.com/transcript/message/35702898#35702898 – TylerH Feb 16 '17 at 22:12
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    http://stackoverflow.com/questions/18532691/how-do-i-write-a-backslash-in-a-string – Thomas Weller Feb 16 '17 at 22:12
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    @ThomasWeller That's a much better dupe, thanks to Servy for Mjolniring it as a dupe of that one. – TylerH Feb 16 '17 at 22:16
  • related: http://stackoverflow.com/questions/14583874/verbatim-string-literals-v-escape-sequences – rene Feb 16 '17 at 22:17
  • Note, for filesystem paths, you don't need to use backslashes in place of slashes in .NET (except if you are passing the path as a string outside of .NET to somewhere that uses backslashes for something else or doesn't understand slashes as a directory separator). – Tom Blodget Feb 16 '17 at 23:29

2 Answers2

2

Using strings in C# you need to Escape characters using Escape Sequences

Escape Sequences

Character combinations consisting of a backslash () followed by a letter or by a combination of digits are called "escape sequences." To represent a newline character, single quotation mark, or certain other characters in a character constant, you must use escape sequences. An escape sequence is regarded as a single character and is therefore valid as a character constant.

Escape sequences are typically used to specify actions such as carriage returns and tab movements on terminals and printers. They are also used to provide literal representations of nonprinting characters and characters that usually have special meanings, such as the double quotation mark ("). The following table lists the ANSI escape sequences and what they represent.

Note that the question mark preceded by a backslash (\?) specifies a literal question mark in cases where the character sequence would be misinterpreted as a trigraph. See Trigraphs for more information.

\a  Bell (alert)
\b  Backspace
\f  Formfeed
\n  New line
\r  Carriage return
\t  Horizontal tab
\v  Vertical tab
\'  Single quotation mark
\"  Double quotation mark
\\  Backslash
\?  Literal question mark
\ ooo   ASCII character in octal notation
\x hh   ASCII character in hexadecimal notation
\x hhhh Unicode character in hexadecimal notation if this escape sequence is used in a wide-character constant or a Unicode string literal.

For example, WCHAR f = L'\x4e00' or WCHAR b[] = L"The Chinese character for one is \x4e00".
Nico
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0

Slashes are not doubled - they are just escaped, because backslash has special meaning in C# strings. Character combination of backslash followed by some characters is called escape sequence. They are used to represent nonprintable characters, actions like carriage returns and characters which has special meaning like double quotes or backslashes.

Samples of escape sequences :

  • \n - new line
  • \t - horizontal tab
  • \" - double quotes
  • \\ - backslash

So if you want to have backslash character in your string:

"C:\Users\Tim\Download"

you should either use corresponding escape sequence:

"C:\\Users\\Tim\\Download"

Or you can use verbatim string. In verbatim string escape sequences are not processed

@"C:\Users\Tim\Download"

Further reading: Escape Sequences

Sergey Berezovskiy
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