This question already has answers here:
Can I escape a double quote in a verbatim string literal?
(6 answers)
Closed 9 years ago.
I am a bit new to c#, and i am stuck at this point,
I have a regular string, where i made use of \ to escape ", escape here means that to escape the compilers interpretation of ", and get " printed on the screen, and i get the expected output-->
class Program
{
static void Main(string[] args)
{
string s1 = "This is a \"regular\" string";
System.Console.WriteLine(s1);
System.Console.Read();
}
}
o/p--> This is a "regular" string
Now, i have a verbatim string, and i am trying to escape " using \ in the same manner as above..-->
class Program
{
static void Main(string[] args)
{
string s2 = #"This is \t a \"verbatim\" string";//this would escape \t
System.Console.WriteLine(s2);
System.Console.Read();
}
}
Why the above isn't working ?
Use a double quote:
string s2 = #"This is \t a ""verbatim"" string";
With C# 11 you could also use a raw string literal, for example:
string longMessage = """
This is a long message.
It has several lines.
Some are indented
more than others.
Some should start at the first column.
Some have "quoted text" in them.
""";
Raw string literals are a new format for string literals. Raw string literals can contain arbitrary text, including whitespace, new lines, embedded quotes, and other special characters without requiring escape sequences. A raw string literal starts with at least three double-quote (""") characters. It ends with the same number of double-quote characters.
If you want to write a verbatim string containing a double-quote you must write two double-quotes.
string s2 = #"This is \t a ""verbatim"" string";
This is covered in section 2.4.4.5 of the C# specification:
2.4.4.5 String literals
C# supports two forms of string literals: regular string literals and verbatim string literals.
A regular string literal consists of zero or more characters enclosed in double quotes, as in "hello", and may include both simple escape sequences (such as \t for the tab character) and hexadecimal and Unicode escape sequences.
A verbatim string literal consists of an # character followed by a double-quote character, zero or more characters, and a closing double-quote character. A simple example is #"hello". In a verbatim string literal, the characters between the delimiters are interpreted verbatim, the only exception being a quote-escape-sequence. In particular, simple escape sequences and hexadecimal and Unicode escape sequences are not processed in verbatim string literals. A verbatim string literal may span multiple lines.
In a Verbatim string, backslashes are treated as standard characters, not escape characters. The only character that needs escaping is the quotation marks, which you can escape using the very same character:
string s2 = #"This is \t a ""verbatim"" string";
Of course you can never add special characters like \t (tab) using this method, so it is only useful for simple strings - I think I only ever use this when working with file paths.
Related
In a verbatim string literal (#"foo") in C#, backslashes aren't treated as escapes, so doing \" to get a double quote doesn't work. Is there any way to get a double quote in a verbatim string literal?
This understandably doesn't work:
string foo = #"this \"word\" is escaped";
Use a duplicated double quote.
#"this ""word"" is escaped";
outputs:
this "word" is escaped
Use double quotation marks.
string foo = #"this ""word"" is escaped";
For adding some more information, your example will work without the # symbol (it prevents escaping with \), this way:
string foo = "this \"word\" is escaped!";
It will work both ways but I prefer the double-quote style for it to be easier working, for example, with filenames (with lots of \ in the string).
This should help clear up any questions you may have: C# literals
Here is a table from the linked content:
Regular literal
Verbatim literal
Resulting string
"Hello"
#"Hello"
Hello
"Backslash: \\"
#"Backslash: \"
Backslash: \
"Quote: \""
#"Quote: """
Quote: "
"CRLF:\r\nPost CRLF"
#"CRLF:Post CRLF"
CRLF:Post CRLF
Update: With C# 11 Preview feature - Raw String Literals
string foo1 = """
this "word" is escaped
""";
string foo2 = """this "word" is escaped""";
History:
There is a proposal open in GitHub for the C# language about having better support for raw string literals. One valid answer, is to encourage the C# team to add a new feature to the language (such as triple quote - like Python).
see https://github.com/dotnet/csharplang/discussions/89#discussioncomment-257343
As the documentation says:
Simple escape sequences ... are interpreted literally. Only a quote escape sequence ("") is not interpreted literally; it produces one double quotation mark. Additionally, in case of a verbatim interpolated string brace escape sequences ({{ and }}) are not interpreted literally; they produce single brace characters.
In a verbatim string literal (#"foo") in C#, backslashes aren't treated as escapes, so doing \" to get a double quote doesn't work. Is there any way to get a double quote in a verbatim string literal?
This understandably doesn't work:
string foo = #"this \"word\" is escaped";
Use a duplicated double quote.
#"this ""word"" is escaped";
outputs:
this "word" is escaped
Use double quotation marks.
string foo = #"this ""word"" is escaped";
For adding some more information, your example will work without the # symbol (it prevents escaping with \), this way:
string foo = "this \"word\" is escaped!";
It will work both ways but I prefer the double-quote style for it to be easier working, for example, with filenames (with lots of \ in the string).
This should help clear up any questions you may have: C# literals
Here is a table from the linked content:
Regular literal
Verbatim literal
Resulting string
"Hello"
#"Hello"
Hello
"Backslash: \\"
#"Backslash: \"
Backslash: \
"Quote: \""
#"Quote: """
Quote: "
"CRLF:\r\nPost CRLF"
#"CRLF:Post CRLF"
CRLF:Post CRLF
Update: With C# 11 Preview feature - Raw String Literals
string foo1 = """
this "word" is escaped
""";
string foo2 = """this "word" is escaped""";
History:
There is a proposal open in GitHub for the C# language about having better support for raw string literals. One valid answer, is to encourage the C# team to add a new feature to the language (such as triple quote - like Python).
see https://github.com/dotnet/csharplang/discussions/89#discussioncomment-257343
As the documentation says:
Simple escape sequences ... are interpreted literally. Only a quote escape sequence ("") is not interpreted literally; it produces one double quotation mark. Additionally, in case of a verbatim interpolated string brace escape sequences ({{ and }}) are not interpreted literally; they produce single brace characters.
Double quotes can be escaped like this:
string test = #"He said to me, ""Hello World"". How are you?";
But this involves adding character " to the string. Is there a C# function or other method to escape double quotes so that no changing in string is required?
No.
Either use verbatim string literals as you have, or escape the " using backslash.
string test = "He said to me, \"Hello World\" . How are you?";
The string has not changed in either case - there is a single escaped " in it. This is just a way to tell C# that the character is part of the string and not a string terminator.
You can use backslash either way:
string str = "He said to me, \"Hello World\". How are you?";
It prints:
He said to me, "Hello World". How are you?
which is exactly the same that is printed with:
string str = #"He said to me, ""Hello World"". How are you?";
Here is a DEMO.
" is still part of your string.
You can check Jon Skeet's Strings in C# and .NET article for more information.
In C# you can use the backslash to put special characters to your string.
For example, to put ", you need to write \".
There are a lot of characters that you write using the backslash:
Backslash with other characters
\0 nul character
\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
Any character substitution by numbers:
\xh to \xhhhh, or \uhhhh - Unicode character in hexadecimal notation (\x has variable digits, \u has 4 digits)
\Uhhhhhhhh - Unicode surrogate pair (8 hex digits, 2 characters)
Another thing worth mentioning from C# 6 is interpolated strings can be used along with #.
Example:
string helloWorld = #"""Hello World""";
string test = $"He said to me, {helloWorld}. How are you?";
Or
string helloWorld = "Hello World";
string test = $#"He said to me, ""{helloWorld}"". How are you?";
Check running code here!
View the reference to interpolation here!
You're misunderstanding escaping.
The extra " characters are part of the string literal; they are interpreted by the compiler as a single ".
The actual value of your string is still He said to me, "Hello World". How are you?, as you'll see if you print it at runtime.
2022 UPDATE: Previously the answer would have been "no". However, C#11 introduces a new feature called "raw string literals." To quote the Microsoft documentation:
Beginning with C# 11, you can use raw string literals to more easily create strings that are multi-line, or use any characters requiring escape sequences. Raw string literals remove the need to ever use escape sequences. You can write the string, including whitespace formatting, how you want it to appear in output."
SOURCE: https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/#raw-string-literals
EXAMPLE: So using the original example, you could do this (note that raw string literals always begin with three or more quotation marks):
string testSingleLine = """He said to me, "Hello World". How are you?""";
string testMultiLine = """
He said to me, "Hello World". How are you?
""";
Please explain your problem. You say:
But this involves adding character " to the string.
What problem is that? You can't type string foo = "Foo"bar"";, because that'll invoke a compile error. As for the adding part, in string size terms that is not true:
#"""".Length == 1
"\"".Length == 1
In C# 11.0 preview you can use raw string literals.
Raw string literals are a new format for string literals. Raw string literals can contain arbitrary text, including whitespace, new lines, embedded quotes, and other special characters without requiring escape sequences. A raw string literal starts with at least three double-quote (""") characters. It ends with the same number of double-quote characters. Typically, a raw string literal uses three double quotes on a single line to start the string, and three double quotes on a separate line to end the string.
string test = """He said to me, "Hello World" . How are you?""";
In C#, there are at least four ways to embed a quote within a string:
Escape quote with a backslash
Precede string with # and use double quotes
Use the corresponding ASCII character
Use the hexadecimal Unicode character
Please refer this document for detailed explanation.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
What's the # in front of a string in C#?
why do we use # to replace \ with another string using string.replace(#"\","$$")
i'm using C# windows application
The # in front of a string literal makes it a verbatim string literal, so the backslash \ does not need to be doubled. You can use "\\" instead of #"\" for the same effect.
Because if you didn't, you'd have to escape \ with \\
# is used to what's called verbatim strings
In C#, you can prefix a string with # to make it verbatim, so you don't need to escape special characters.
#"\"
is identical to
"\\"
The C# Language Specification 2.4.4.5 String literals states:
C# supports two forms of string literals: regular string literals and
verbatim string literals.
A regular string literal consists of zero or more characters enclosed
in double quotes, as in "hello", and may include both simple escape
sequences (such as \t for the tab character), and hexadecimal and
Unicode escape sequences.
A verbatim string literal consists of an # character followed by a
double-quote character, zero or more characters, and a closing
double-quote character. A simple example is #"hello". In a verbatim
string literal, the characters between the delimiters are interpreted
verbatim, the only exception being a quote-escape-sequence. In
particular, simple escape sequences, and hexadecimal and Unicode
escape sequences are not processed in verbatim string literals. A
verbatim string literal may span multiple lines.
The verbatim string literal, which uses the # character, makes it a little easier in practicality to escape almost all the characters that you would otherwise have to escape individually with the \ character in a string.
Note: the " char will still require escaping even with the verbatim mode.
So I would use it to save time from having to go through a long string to escape all the necessary characters that needed escaping.
Because the backslash is treated as an escape character and you would get an 'Unrecognised escape sequence' error if you didn't use '#'. Using '#' tells the compiler to ignore escape characters. this may be helpful.
I have a trial version of ReSharper and it always suggests that I switch regular strings to verbatim strings. What is the difference?
A verbatim string is one that does not need to be escaped, like a filename:
string myFileName = "C:\\myfolder\\myfile.txt";
would be
string myFileName = #"C:\myfolder\myfile.txt";
The # symbol means to read that string literally, and don't interpret control characters otherwise.
This is covered in section 2.4.4.5 of the C# specification:
2.4.4.5 String literals
C# supports two forms of string literals: regular string literals and verbatim string literals.
A regular string literal consists of zero or more characters enclosed in double quotes, as in "hello", and may include both simple escape sequences (such as \t for the tab character) and hexadecimal and Unicode escape sequences.
A verbatim string literal consists of an # character followed by a double-quote character, zero or more characters, and a closing double-quote character. A simple example is #"hello". In a verbatim string literal, the characters between the delimiters are interpreted verbatim, the only exception being a quote-escape-sequence. In particular, simple escape sequences and hexadecimal and Unicode escape sequences are not processed in verbatim string literals. A verbatim string literal may span multiple lines.
In other words the only special character in a #"verbatim string literal" is the double-quote character. If you wish to write a verbatim string containing a double-quote you must write two double-quotes. All other characters are interpreted literally.
You can even have literal new lines in a verbatim string literal. In a regular string literal you cannot have literal new lines. Instead you must use for example "\n".
Verbatim strings literals are often useful for embedding filenames and regular expressions in the source code, because backslashes in these types of strings are common and would need to be escaped if a regular string literal were used.
There is no difference at runtime between strings created from regular string literals and strings created from a verbatim string literals - they are both of type System.String.
There is no runtime difference between a string and verbatim string. They're only different at compile time. The compiler accepts fewer escape sequences in a verbatim string so what-you-see-is-what-you-get other than a quote escape.
You can also use the verbatim character, #, to tell the compiler to treat a keyword as a name:
var #if = "if";
//okay, treated as a name
Console.WriteLine(#if);
//compiler err, if without # is a keyword
Console.WriteLine(if);
var #a = "a";
//okay
Console.WriteLine(#a);
//also okay, # isn't part of the name
Console.WriteLine(a);
You can have multiline string too using verbatim strings:
Console.WriteLine(#"This
is
a
Test
for stackoverflow");
without # you got an error.
In VB14 there is a new feature called Multiline Strings, it's like verbatim strings in C#.
Pro tip: VB string literals are now exactly like C# verbatim strings.
Regular strings use special escape sequences to translate to special characters.
/*
This string contains a newline
and a tab and an escaped backslash\
*/
Console.WriteLine("This string contains a newline\nand a tab\tand an escaped backslash\\");
Verbatim strings are interpreted as is, without translating any escape sequences:
/*
This string displays as is. No newlines\n, tabs\t or backslash-escapes\\.
*/
Console.WriteLine(#"This string displays as is. No newlines\n, tabs\t or backslash-escapes\\.");
If you want to suppress the ReSharper warnings, you can use:
Localizable(false)
For things like parameters, file locations, etc., this could be a good solution.