I have a config file, myapp.exe.config.
In the file I have an attribute with a fullpath filename as the value.
<add key="InfoFile" value="c:\temp\info.txt" />
It seems to work if I use a single or double backslash. That is,
<add key="InfoFile" value="c:\\temp\\info.txt" />
works also. What is the correct way to do this?
You don't need that. Anything within an attribute value is character data.
Since you're reading these values using C#, they'll get escaped as if they would be a literal path string in code.
Anyway, you might want to know that C# has # operator to declare verbatim strings, meaning that you don't need to escape backslashes when using literal paths in code:
string somePath = #"C:\blah\blih\bluh.txt";
A backslash has no special meaning in XML, so they should not be escaped.
Besides, if you would escape the backslashes in XML you would not use \\, you would use \.
The reason that it works with double backslashes also is that the file system is forgiving. You can use the path c:\\temp\\info.txt to reach the file c:\temp\info.txt.
Basically URL or URI holds single slash \ so, its better to use single slash. The problem comes while writing code, but in XML there is no problem to use single slash.
I think the best would to prevent the double backslash just in case, but if it works why change it. Maybe replace "\\" with "\" when you read the config value into your application.
Related
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
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'm converting from VB to C#, and in C# I seem not to be able to simply write a path string to the application settings..
D:\Something becomes D:\\Something
I tried also #"D:\Something", but that also doesn't work.
So what is the correct way? Say I want to have two settings; path and filename. How shall I format them, for the purpose of Path.Combine to make this a valid file-path/name for a database, or in other words, to have single backslashes?
Your code is working correctly - when you read a string with doubled slashes back, they becomes single slashes again. This is called escaping. It is designed to let you enter special characters as sequences starting in \. Single slash becomes special in this scheme, so you need to escape it with a slash as well.
My program outputs strings like "Wzyryrff}av{v5~fvzu: Bb``igbuz~+\177Ql\027}C5]{H5LqL{" and the problem is the escape codes (\\\ instead of \, \177 instead of the character, etc.)
I need a way to unescape the string of all escape codes (mainly just the \\\ and octal \027 types). Is there something that already does this?
Thanks
Reference: http://www.tailrecursive.org/postscript/escapes.html
The strings are an encrypted value and I need to decrypt them, but I'm getting the wrong values since the strings are escaped
It sounds more like it's encoded rather than simply escaped (if \177 is really a character). So, try decoding it.
There is nothing built in to do exactly this kind of escaping.
You will need to parse and replace these sequences yourself.
The \xxx octal escapes can be found with a RegEx (\\\d{3}), iterating over the matches will allow you to parse out the octal part and get the replacement character for it (then a simple replace will do).
The others appear to be simple to replace with string.Replace.
If the string is encrypted then you probably need to treat it as binary and not text. You need to know how it is encoded and decode it accordingly. The fact that you can view it as text is incidental.
If you want to replace specific contents you can just use the .Replace() method.
i.e. myInput.Replace("\\", #"\")
I am not sure why the "\" is a problem for you. If it its actually an escape code then it just should be fine since the \ represents the \ in a string.
What is the reason you need to "remove" the escape codes?
I have a helper class pulling a string from an XML file. That string is a file path (so it has backslashes in it). I need to use that string as it is... How can I use it like I would with the literal command?
Instead of this:
string filePath = #"C:\somepath\file.txt";
I want to do this:
string filePath = #helper.getFilePath(); //getFilePath returns a string
This isn't how I am actually using it; it is just to make what I mean a little clearer. Is there some sort of .ToLiteral() or something?
I don't think you have to worry about it if you already have the value. The # operator is for when you're specifying the string (like in your first code snippet).
What are you attempting to do with the path string that isn't working?
I'm not sure if I understand. In your example: if helper.getFilePath() returns "c:\somepath\file.txt", there will be no problem, since the # is only needed if you are explicitely specifying a string with "".
When Functions talk to each other, you will always get the literal path. If the XML contains c:\somepath\file.txt and your function returns c:\somepath\file.txt, then string filePath will also contain c:\somepath\file.txt as a valid path.
The #"" just makes it easier to write string literals.
string (C# Reference, MSDN)
Verbatim string literals start with # and are also enclosed in double quotation marks. For example:
#"good morning" // a string literal
The advantage of verbatim strings is that escape sequences are not processed, which makes it easy to write, for example, a fully qualified file name:
#"c:\Docs\Source\a.txt" // rather than "c:\\Docs\\Source\\a.txt"
One place where I've used it is in a regex pattern:
string pattern = #"\b[DdFf][0-9]+\b";
If you have a string in a variable, you do not need to make a "literal" out of it, since if it is well formed, it already has the correct contents.
In C# the # symbol combined with doubles quotes allows you to write escaped strings. E.g.
print(#"c:\mydir\dont\have\to\escape\backslashes\etc");
If you dont use it then you need to use the escape character in your strings.
http://msdn.microsoft.com/en-us/library/aa691090(VS.71).aspx
You dont need to specify it anywhere else in code. In fact doing so should cause a compiler error.
You've got it backwards. The #-operator is for turning literals into strings, while keeping all funky characters. Your path is already a string - you don't need to do anything at all to it. Just lose the #.
string filePath = helper.getFilePath();
The string returned from your helper class is not a literal string so you don't need to use the '#' character to remove the behaviour of the backslashes.