I want to write something like this C:\Users\UserName\Documents\Tasks in a textbox:
txtPath.Text = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)+"\Tasks";
I get the error:
Unrecognized escape sequence.
How do I write a backslash in a string?
The backslash ("\") character is a special escape character used to indicate other special characters such as new lines (\n), tabs (\t), or quotation marks (\").
If you want to include a backslash character itself, you need two backslashes or use the # verbatim string:
var s = "\\Tasks";
// or
var s = #"\Tasks";
Read the MSDN documentation/C# Specification which discusses the characters that are escaped using the backslash character and the use of the verbatim string literal.
Generally speaking, most C# .NET developers tend to favour using the # verbatim strings when building file/folder paths since it saves them from having to write double backslashes all the time and they can directly copy/paste the path, so I would suggest that you get in the habit of doing the same.
That all said, in this case, I would actually recommend you use the Path.Combine utility method as in #lordkain's answer as then you don't need to worry about whether backslashes are already included in the paths and accidentally doubling-up the slashes or omitting them altogether when combining parts of paths.
To escape the backslash, simply use 2 of them, like this:
\\
If you need to escape other things, this may be helpful..
There is a special function made for this Path.Combine()
var folder = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
var fullpath = path.Combine(folder,"Tasks");
Just escape the "\" by using + "\\Tasks" or use a verbatim string like #"\Tasks"
txtPath.Text = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)+"\\\Tasks";
Put a double backslash instead of a single backslash...
even though this post is quite old I tried something that worked for my case .
I wanted to create a string variable with the value below:
21541_12_1_13\":null
so my approach was like that:
build the string using verbatim
string substring = #"21541_12_1_13\"":null";
and then remove the unwanted backslashes using Remove function
string newsubstring = substring.Remove(13, 1);
Hope that helps.
Cheers
Related
So in microsoft visual studio I have a string that is compiled into a regex. My string is "#(\d+(.\d+)?)=(\d+(.\d+)?)". I cannot compile my program because I get an error saying that \d is a unrecognized escape character. How do I tell it to shut up and let me regex like a pro?
Begin your string with #, that causes the compiler to leave (almost) all characters alone, unescaped (the exception is ", which can be escaped as ""):
#"#(\d+(.\d+)?)=(\d+(.\d+)?"
The problem is that c# does not like the \d inside the string. Use a verbatim string instead
string pattern = #"#(\d+(.\d+)?)=(\d+(.\d+)?)";
The "#" denotes it. C# will not look for escape sequences in the string. If you have to escape a " use two "".
Of cause you can use normal strings. but then you will have to escape the backslashes
string pattern = "#(\\d+(.\\d+)?)=(\\d+(.\\d+)?)";
If you're using a normal string, you need to escape your backslashes, like so:
"#(\\d+(.\\d+)?)=(\\d+(.\\d+)?)"
Basically, you're putting a literal string into C#; the C# compiler sees the string first, and tries to interpret \d as an escape sequence (which doesn't exist, hence error). Therefore, you use \\d to get the C# compiler to see the string as \d, which then gets passed to the regex engine (which does recognize \d as something meaningful). (yes, if you want to match a literal backslash in your regex pattern, you need to use \\\\)
But in C#, you have the alternative of just prepending the string with # to get the compiler to leave the string alone (though " still needs escaping), so that would be like this:
#"#(\d+(.\d+)?)=(\d+(.\d+)?)"
You could also use a verbatim string literal (I prefer to use these because of readability).
Use #"(#\d+(.\d+)?)=(\d+(.\d+)?)"
The #" sign indicates that the string shouldn't interpret escaped characters (A character prefixed by a \) until the closing " is reached.
Note: You can match a single " in your search pattern by double quoting instead "". For instance you can match "Hello" by using the pattern #"""\w+"""
I have a StringBuilder object and wanted to used its Append() method to add this whole string to it:
so I used "#" and copy pasted that whole string like this, but it gives a lot of errors such as "; expected ", "Invalid Expression '<'" , etc
myString.Append(#"COPY-PASTED-THAT_WHOLE-STRING");
What is the correct way of adding this string to my string builder object?
Thank you.
Even with an # prefixing the string, you need to escape any " characters, otherwise they will be interpreted as the end of the string literal.
EDIT:
e.g.
var entity = #"<!ENTITY xsd ""http://www.w3.org/2001/XMLSchema#"">";
Double-quotes (") inside the string you want to paste need to be escaped by being replaced with two consecutive double-quotes, as in "". Here's a trick to use:
Paste your string into a new instance of Notepad
Replace all double quotes (") with two double quotes ("")
Select and copy the content from Notepad back into clipboard
Paste it into #"…" in your code/text editor
From C# docs:
In a verbatim string literal, the characters between the delimiters
are interpreted verbatim, the only exception being a
quote-escape-sequence.
You can use the # syntax to add multiple lines. But you need to escape the "s inside your string by using ""
For example
#"<Ontology xmlns=""http://www.w3.org/2002/07/owl#"""
If you don't escape them, C# will treat the quote mark as the end of the string.
One option, as others have said, is to escape all of the double quotes (") with a double double quote ("").
What I prefer to do, as it makes the code more readable, when adding an XML block as a literal string, is to use single quotes rather than double quotes. Just put the XML file into a text editor and do a replace all on double quote with a single quote (').
Another option, since your XML literal isn't all that short, is to put it into a file and read in that file at runtime.
You can escape them like this as well...
#"<Ontology xmlns=\"http://www.w3.org/2002/07/owl#\""
I am using .NET (C#) code to write to a database that interfaces with a Perl application. When a single quote appears in a string, I need to "escape" it. IOW, the name O'Bannon should convert to O\'Bannon for the database UPDATE. However, all efforts at string manipulation (e.g. .Replace) generate an escape character for the backslash and I end up with O\\'Bannon.
I know it is actually generating the second backslash, because I can read the resulting database field's value (i.e. it is not just the IDE debug value for the string).
How can I get just the single backslash in the output string?
R
Well I did
"O'Bannon".Replace("'","\\'")
and result is
"O\'Bannon"
Is this what you want?
You can use "\\", which is the escape char followed by a backslash.
See the list of Escape Sequences here: http://msdn.microsoft.com/en-us/library/h21280bw.aspx
even better assign a var to the replace so that you can check it as well if needed
var RepName = "O'Bannon";
var Repstr = RepName.Replace("'","\\'");
You can also use a verbatim string
s = s.Replace("'", #"\'");
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
What's the # in front of a string for .NET?
I have the following code:
new Attachment(Request.PhysicalApplicationPath + #"pdf\" + pdfItem.Value)
What does the # sign do?
It has nothing to do with filepath. It changes the escaping behavior of strings.
In a string literal prefixed with # the escape sequences starting with \ are disabled. This is convenient for filepaths since \ is the path separator and you don't want it to start an escape sequence.
In a normal string you would have to escape \ into \\ so your example would look like this "pdf\\". But since it's prefixed with # the only character that needs escaping is " (which is escaped as "") and the \ can simply appear.
This feature is convenient for strings literals containing \ such as filepaths or regexes.
For your simple example the gain isn't that big, but image you have a full path "C:\\ABC\\CDE\\DEF" then #"C:\ABC\CDE\DEF" looks a lot nicer.
For regular expressions it's almost a must. A regex typically contains several \ escaping other characters already and often becomes almost unreadable if you need to escape them.
It's a verbatim string literal.
This allows the string to contain backslashes and even linebreaks without them being handled differently:
string multiLineString = #"First line
second line
third line";
As backslashes aren't used for escaping, inserting a double quote into the string requires it to be doubled:
string withQuote = #"before""after";
Verbatim string literals are typically used for file paths (as you've shown) and regular expressions, both of which frequently use backslashes.
See my article on strings for more information.
It allows you to enter the backslash (\) without escaping it:
var s1 = "C:\\Temp\\MyFileName";
var s2 = #"C:\Temp\MyFileName";
Both result in a string with the same contents (and since strings are interned at compile time, probably even the same string reference).
Is there another way of assigning string path to variable aside from this:
strPath = #"C:\Myfile.txt";
is there another way instead using "#" sign in the string path.
thanks.
You can escape it:
var myPath = "C:\\MyFile.txt"
Do you mean another way of escaping the backslashes?
The # sign at the start means that the string is treated as a verbatim string literal, and simple escape sequences such as \n or \t are ignored.
If you don't put the # at the start it is not verbatim, and escape sequences are parsed. If you want to ignore an individual escape sequence you can precede it with a single backslash and it will be ignored.
The reason you would use it in a path such as your example is so that you don't have to escape each individual backslash as you would if you didn't put the # at the start:
strPath = "C:\\Myfile.txt";
You can use forward slashes and it'll work fine on Windows and no escaping needed.
strPath = "C:/Myfile.txt";
You can use Unicode Escape Sequences....
string strPath = "C:\u005CMyfile.txt";
string path = Path.Combine("C:", "myfile.txt");