Please forgive me a beginner's question :)
string S="abc";
S+="\";
won't complile.
string S="abc";
S+="\\";
will make S="abc\\"
How can I make S="abc\" ?
Your second piece of code is what you want (or a verbatim string literal #"\" as others have suggested), and it only adds a single backslash - print it to the console and you'll see that.
These two pieces of code:
S += "\\";
and
S += #"\";
are exactly equivalent. In both cases, a single backslash is appended1.
I suspect you're getting confused by the debugger view, which escapes backslashes (and some other characters). You can validate that even with the debugger by looking at S.Length, which you'll see is 4 rather than 5.
1 Note that it doesn't change the data in the existing string, but it sets the value of S to refer to a new string which consists of the original with a backslash on the end. String objects in .NET are immutable - but that's a whole other topic...
Try this:
String S = "abc";
S += #"\";
# = verbatim string literal
http://msdn.microsoft.com/en-us/library/aa691090%28v=vs.71%29.aspx
http://msdn.microsoft.com/en-us/library/vstudio/362314fe.aspx
string S = "abs" + "\\";
Should and does result in abc\.
What you are probably seeing is the way the debugger/intellisense visualizes the string for you.
Try printing your string to the console or display it in a textbox.
You already have the solution. The reason it appears as abc\\ whilst debugging is because VS will escape backslashes, print the value of S to a console window and you'll see abc\.
You could add an # to the start of the string literal, e.g.
string S="abc";
S+= #"\";
Which will achieve the same thing.
You can escape the backslash with the # character:
string S="abc";
S += #"\";
But this accomplishes exactly what you've written in your second example. The confusion on this is stemming from the fact that the Visual Studio debugger continues to escape these characters, even though your source string will contain only a single backslash.
Your second example is perfectly fine
string S="abc";
S+="\\";
Visual studio displays string escaped, that's why you see two slashes in result string. If you don't want to use escaping declare string like this
#"\"
This is not compiling because compiler is expecting a character after escape symbol
string S="abc";
S+="\";
string S="abc";
S+="\\";
Console.WriteLine(S); // This is what you're missing ;)
You'll see your string is not wrong at all.
The backslash (\) is an escape character, and allows you to get special characters that you wouldn't normally be able to insert in a string, such as "\r\n", which represents a NewLine character, or "\"" which basically gives you a " character.
In order to get the \ character, you need to input "\\" which is exactly what you're doing and also what you want.
Using the verbatim (#) replaces all occurrences of \ into \\, so #"\" == "\\". This is usually used for paths and regexes, where literal \ are needed in great numbers. Saying #"C:\MyDirectory\MyFile" is more comfortable than "C:\\MyDirectory\\MyFile" after all.
Try this
string s="abc";
s = s+"\\";
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
Maybe I am missing something here
I have a variable dir coming in looking something like \\\\SERVERNAME\\dir\\subdir
I need it to look like \\SERVERNAME\dir\subdir
I used string.Replace routine but it did not replace the double slashes, the problem is that when i try to use the path as is, it doesn't find the file.
How would I use string.Replace here in order to get a valid path?
dir.Replace(#"\\", #"\") should do the trick.
In C# the backslash character, "\", is used to escape characters in strings. For example, in the string "Hello\nworld", the "\n" represents a newline character. So, in general, when C# sees a "\" in a string it expects to treat it as part of a special command character, rather than as a literal "\".
So, how do you tell C# that you want a literal backslash to appear in your string, that it isn't part of a special command character? You escape the backslash. And the escape character is also a backslash. So to tell C# that you really want a literal "\" to appear in your string (eg in a file path) you use two backslashes: "\\".
Say I wanted to set a variable to the following path: C:\Temp\FileDrop
In C# I'd have to do the following:
string myPath = "C:\\Temp\\FileDrop";
I suspect that when you see the value of a variable looking like \\\\SERVERNAME\\dir\\subdir it is escaping the backslash characters so the real value of the variable is \\SERVERNAME\dir\subdir.
By the way, if you're copying and pasting long paths from, say, Windows Explorer, it can be a real pain to have to double up the backslashes to escape them. So C# has a special string literal character, "#". If you prefix a string with a "#" then it will treat the string exactly as written. eg
string myPath = #"C:\Temp\FileDrop";
I have the following string:
"\\\\AAA.AA.A.AA\\d$\\ivr\\vm\\2012May\\29\\10231_1723221348.vox"
I would like it to look like:
"\\AAA.AA.A.AA\d$\ivr\vm\2012May\29\10231_1723221348.vox"
I have tried
fileToConvert.Replace(#"\\",#"\")
This produces:
"\\AAA.AA.A.AA\\d$\\ivr\\vm\\2012May\\29\\10231_1723221348.vox"
Why?!?
Thanks all!
I'm guessing you are inspecting the result string in the debugger. This string will be escaped, i.e. TAB is \t and return is \n. The "real" value can be inspected by clicking the magnifying glass icon next to the value.
Also, doing a print to terminal (e.g. System.Console.WriteLine()) will show the "correct" value.
I guess you look in the debugger and thats why you get this behaviour...
each \\ is actually one \. thats why you get the \\\\ replaced to \\ (two "\" replaced by one)
and because \\ is actually only one "\" you still gets "\" after the replacement (because it didn't find two "\" string
the reason is that the \ character marks a special character, for example if you want to have tab (\t) character you will have the string "\t" for new line "\r\n".
so when you actually want to have a '\' character in a string you mark it with one more '\' char before - like "\\"
that mean that when you see "\\AAA.AA.A.AA\d$\ivr\vm\2012May\29\10231_1723221348.vox" in the debugger, the actual string is "\AAA.AA.A.AA\d$\ivr\vm\2012May\29\10231_1723221348.vox"
so fileToConvert.Replace(#"\\",#"\") will make it look like this:
"\AAA.AA.A.AA\d$\ivr\vm\2012May\29\10231_1723221348.vox"
which you will see in the debugger as "\\AAA.AA.A.AA\\d$\\ivr\\vm\\2012May\\29\\10231_1723221348.vox"
For a conclusion:
You don't need to do anything - not even fileToConvert.Replace(#"\\",#"\") because your original string (what you see in debug as "\\\\AAA.AA.A.AA\\d$\\ivr\\vm\\2012May\\29\\10231_1723221348.vox") is actually "\\AAA.AA.A.AA\d$\ivr\vm\2012May\29\10231_1723221348.vox"
string s = #"\\\\AAA.AA.A.AA\\d$\\ivr\\vm\\2012May\\29\\10231_1723221348.vox";
var output = s.Replace(#"\\",#"\");
I tried above code code and it works fine.
We have the following code:
string str="\\u5b89\u5fbd\\";
We need output in the format:
"\u5b89\u5fbd\"
We have tried this code:
str.Replace("\\",#"\")
Its not working.
Try this
string str = "\\u5b89\u5fbd\\";
str = str.Replace(#"\\", #"\");
\ is a reserved sign. \\ escapes it and results in \
Adding # at the start of a string tell the compiler to use the string as is and not to escape characters.
So use either "\\\\" or #"\\"
EDIT
\\u5b89\u5fbd\\ actually does not have two \ together. \ is just escaped.
The string results in \u5b89徽\. And in that string you can't replace \\ because there is only one \ together.
Have you tried this?
str.Replace("\\\\","\\");
Your example accomplish nothing. "\\" is an escaped version of \, and #"\" is another version of writing \. So your example replaces \ with \
EDIT
Now I understand your problem. What you want can't actually be done, since that would cause the string to end with a single \, and that will not be allowed. \ denotes a start of a escape sequence, and needs something after it.
I think there are no good option here, since in your case \u5b89 is not a string, but an escape sequence for one specific character.
str.Replace("\\u5b89","\u5b89");
This works for your current example, but will only work with this one specific character, so I guess it wont help you much. The \ at the end you cannot replace with \, but I can't see why you need the string to end with this char either.
Your best bet is to make sure that the \ does not occur at the start of the string in the first place, instead of trying to get rid of it afterwards.
Okay so the first string is actually saved as:
"\u5b89[someChineseCharacter]\"
because you are already using escape sequences. If you would like the original string to be what you typed, you have to do it like so:
string str = #"\\u5b89\u5fbd\\";
Then, str = str.Replace(#"\\",#"\") would work.
Some clarification:
When you type string str="\\u5b89\u5fbd\\"; in visual studio, it saves the string \u5b89徽\ in memory, because you are using several escape sequences in the original statement:
\\ actually means \
\u5fbd actually means unicode character 5fbd, which is 徽.
For that reason, these get replaced, and in memory your string looks as mentioned.
So if you try to replace occurrences of two backslashes #"\\", it will appear to do nothing, because there were no such occurrences in the original string to begin with.
Hope this makes it clear.
Try this it will solve your problem.
str.Replace("\\\\","\\");
Or maybe Something like this?
foreach (char c in str)
{
if ((int)c < 256)
Console.Write(c);
else
Console.Write(String.Format("\\u{0:x4}", (int)c));
}
;)
Maybe it is just me but I think the input string should have a "\" in the middle, or the second u5fbd will be interpreted as a unicode char (so you won't get it outputted as you wish). With a starting string like this:
string str="\\u5b89\\u5fbd\\";
You don't need any replace to output what you want, if for "output" you mean something like Console or an HTML page...
"C://test/test/test.png" -> blub
blub = blub.Replace(#"/", #"\");
result = "C:\\\\test\\test\\test.png"
how does that make sense? It replaces a single / with two \
?
It's actually working:
string blub = "C://test/test/test.png";
string blub2 = blub.Replace(#"/", #"\");
Console.WriteLine(blub);
Console.WriteLine(blub2);
Output:
C://test/test/test.png
C:\\test\test\test.png
BUT viewing the string in the debugger does show the effect you describe (and is how you would write the string literal in code without the #).
I've noticed this before but never found out why the debugger chooses this formatting.
No, it doesn't.
What you're seeing is the properly formatted string according to C# rules, and since the output you're seeing is shown as though you haven't prefixed it with the # character, every backslash is doubled up, because that's what you would have to write if you wanted that string in the first place.
Create a new console app and write the result to the console, and you'll see that the string looks like you wanted it to.
So this is just an artifact of how you look at the string (I assume the debugger).
The \ character in C# is the escape character, so if you are going to use it as a \ character you need two - otherwise the next character gets treated specially (new line etc).
See What character escape sequences are available? (C#)
The character \ is a special character, which changes the meaning of the character after it in string literals. So when you refer to \ itself, it needs to be escaped: \\.
Look up "escape characters".
Its done what it should.
"\\" is the same as #"\"
"\" is an escape character. Without the verbatim indicator "#" before a string a single \ is shown as "\\"
You should think twice before saying something like that....
The string.Replace function is basic functionality that has been around for a long time.... Whenever you find you have a problem with something like that, it's probably not the function that is broken, but your understanding or use of it.