I have a string:
var a = "some text \"";
I want to replace \" with ".
a.Replace("\"", '"'); => The best overloaded method match for 'string.Replace(string, string)' has some invalid arguments
a.Replace("\"", """); => Newline in constant
finally I want to obtain "some text"
You need to escape your string, you are looking for:
a.Replace("\\\"", "\"");
That should do it!
NOTE
Please note - just calling replace creates a NEW STRING VALUE it does not edit the original string. If you want to use this string you can do the replace inline or you can assign back to the original value like so:
a = a.Replace("\\\"", "\"");
That could also be another issue you are having!
You seem to be confused by C#'s escaping rules. The literal "some text \"" has the value some text ". If you look at this string in the VS debugger, it will show the C# literal that produces the value: "some text \"". If you print it, you'll see its value is actually some text ".
If the value is actually some text \", which could be represented by "some text \\\"" or #"some text \""", then what you really want is this:
var b = a.Replace("\\\"", "\"");
I suspect that your string is actually already what you want, though: some text "
You can use verbatim strings introduced with #. In verbatim strings double quotes are escaped by doubling them and the backslashes don't work as escape characters any more:
string result = a.Replace(#"\""", #"""");
Compared to normal strings, you still have to escape the double quote ("), but not the backslash (\).
Of course you can combine both solutions:
string result = a.Replace(#"\""", "\"");
See also: What character escape sequences are available?
'\' This will treated as escape character in C# you need to use double quote to replace it with.
see below snippet
string afterreplace = txtBox1.Text.Replace("\\\"", "\"");
You need some escaping! Use this:
a.Replace("\\\"", "\"");
Related
I have a problem which seems simple, but for the life of me, I can't figure out how to accomplish it.
Here is my starting string:
Hello \"this is my string\"
Here is what I want the result to be:
Hello "this is my string"
So basically, I need to replace \" with just ".
I do not want to just remove ALL occurrences of \ since a single backslash could exist elsewhere in my string. I just want to replace occurrences of \" with ".
If string actually contains \":
var replaced = myString.Replace(#"\""", #"""")
You might be confused by a syntaxic trick that C# uses to embed the quote symbol inside of strings. Consider:
string abc = "This is a "quote""; // INVALID SYNTAX, compile will complain
string def = "This is a \"quote\""; // this is ok
In this case the \ character is referred to as an escape character and it tells the compiler to ignore the next character and just put it in the string. The resulting string doesn't actually contain the \ character. If you do this:
string ghi = "This is a \\\"quote\\\""; // this is ok
The resulting string will contain a \ and a ", if you want to replace this you can do the following:
string newghi = ghi.Replace("\\\"", "\"");
This will replace all \" occurrences with "
In case you're allergic to escape characters (in other words, just for fun, written with no escape characters, e.g. neither \\ for \ in a normal string or "" for " in a verbatim string):
myString.Replace(#"\"+'"', '"'.ToString())
Note that the C# debugger shows " as \", so your string might actually just have "s. E.g. string helloWorld = "Hello \"World\""; shows up in the debugger the same as in the code, "Hello \"World\"", not as the string's value, Hello "World".
Try this yourString.Replace("\\\"", "");
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+"\\";
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.
I am sent an XML string that I'm trying to parse via an XmlReader and I'm trying to strip out the \" characters.
I've tried
.Replace(#"\", "")
.Replace("\\''", "''")
.Replace("\\''", "\"")
plus several other ways.
Any ideas?
Were you trying it like this:
string text = GetTextFromSomewhere();
text.Replace("\\", "");
text.Replace("\"", "");
? If so, that's the problem - Replace doesn't change the original string, it returns a new string with the replacement performed... so you'd want:
string text = GetTextFromSomewhere();
text = text.Replace("\\", "").Replace("\"", "");
Note that this will replace each backslash and each double-quote character; if you only wanted to replace the pair "backslash followed by double-quote" you'd just use:
string text = GetTextFromSomewhere();
text = text.Replace("\\\"", "");
(As mentioned in the comments, this is because strings are immutable in .NET - once you've got a string object somehow, that string will always have the same contents. You can assign a reference to a different string to a variable of course, but that's not actually changing the contents of the existing string.)
In .NET Framework 4 and MVC this is the only representation that worked:
Replace(#"""","")
Using a backslash in whatever combination did not work...
Try it like this:
Replace("\\\"","");
This will replace occurrences of \" with empty string.
Ex:
string t = "\\\"the dog is my friend\\\"";
t = t.Replace("\\\"","");
This will result in:
the dog is my friend
\ => \\ and " => \"
so Replace("\\\"","")
Where do these characters occur? Do you see them if you examine the XML data in, say, notepad? Or do you see them when examining the XML data in the debugger. If it is the latter, they are only escape characters for the " characters, and so part of the actual XML data.
Replace(#"\""", "")
You have to use double-doublequotes to escape double-quotes within a verbatim string.
Am using regex.Replace() to replace the whole occurrence of a string.. so I gave like Regex.Replace(str,#stringToReplace,"**"); where stringToReplace = #"session" + "\b";
if i give like that its not replacing.. but if i give like Regex.Replace(str,#"session\b","**"); then its working.. how to avoid this.. i want to pass value which will be set dynamically..
Thanks
nimmi
try
stringToReplace = #"session" + #"\b";
The # here means a verbatim string literal.
When you write "\b" without the # it means the backspace character, i.e. the character with ASCII code 8. You want the string consisting of a backslash followed by a b, which means a word boundary when in a regular expression.
To get this you need to either escape the backslash to make it a literal backslash: "\\b" or make the second string also into a verbatim string literal: #"\b". Note also that the # in #"session" (without the \b) doesn't actually have an effect, although there is no harm in leaving it there.
stringToReplace = "session" + #"\b";
#"session" + "\b"
and
#"session\b"
are not the same string.
In the first case "\b" you don't treat the slash as a slash but as an escape parameter. In the second case you do.
So #"session" + #"\b" should bring the same result