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Replacing double backwards slashes with single ones in c#

I need to replace double quotes with single so that something like this
\\\\servername\\dir1\\subdir1\\
becomes
\\servername\dir1\subdir1\
I tried this
string dir = "\\\\servername\\dir1\\subdir1\\";
string s = dir.Replace(#"\\", #"\");
The result I get is
\\servername\\dir1\\subdir1\\
Any ideas?

You don't need to replace anything here. The backslashes are escaped, that's why they are doubled.
Just like \t represents a tabulator, \\ represents a single \. You can see the full list of Escape Sequences on MSDN.
string dir = "\\\\servername\\dir1\\subdir1\\";
Console.WriteLine(dir);
This will output \\servername\dir1\subdir1\.
BTW: You can use the verbatim string to make it more readable:
string dir = #"\\servername\dir1\subdir1\";

There is no problem with the code for replacing. The result that you get is:
\servername\dir1\subdir1\
When you are looking at the result in the debugger, it's shown as it would be written as a literal string, so a backslash characters is shown as two backslash characters.
The string that you create isn't what you think it is. This code:
string dir = "\\\\servername\\dir1\\subdir1\\";
produces a string containing:
\\servername\dir1\subdir1\
The replacement code does replace the \\ at the beginning of the string.
If you want to produce the string \\\\servername\\dir1\\subdir1\\, you use:
string dir = #"\\\\servername\\dir1\\subdir1\\";
or:
string dir = "\\\\\\\\servername\\\\dir1\\\\subdir1\\\\";

This string "\\\\servername\\dir1\\subdir1\\" is the same as #"\\servername\dir1\subdir1\". In order to escape backslashes you need either use # symbol before string, or use double backslash instead of one.
Why you need that? Because in C# backslash used for escape sequences.

How to quote \" (slash double-quote) in a string literal?

This is probably a really simple question but I can't seem to get my head around it. I need to have a string that contains \" without it seeing it as an escape character. I tried using # but it won't work. The only other way I thought of doing this would be to use \u0022 but don't want to unless I can help it.
Desired string - string s = "\"\""; // Obviously this doesn't work!
Desired console output - \"\"
Hope this makes sense.
Thanks!

Try
string s = "\\\"\\\"";
You have to escape your backslashes too.
Mike

You can use the literal, but you need to double-up quotes.
string s = #"\""\""";

In verbatim string literals (#"...") a " in the string value is encoded as "", which happens to also be the only escape sequence in verbatim strings.
#"\""Happy coding!\""" // => \"Happy coding!\"
"\\\"Happy coding!\\\"" // => \"Happy coding!\"
Note that in the 2nd case (not a verbatim string literal), a \ is required before the \ and the " to escape them and prevent their normal meanings.
See the C# string reference for more details and examples.

I think you have to escape backslashes too... so something like "\\\"\\\"" should work, I believe.

Use this string:
string s = "\\\"\\\"";

Console.WriteLine( "\\\"\\\"" );
Just put a \ before each character that needs to be printed.

String s = #"\""\""";
DblQuote characters will escape a second dblquote character
Though for better readability I would go with:
const String DOUBLEQUOTE = """";
const String BACKSLASH = #"\";
String s = BACKSLASH + DOUBLEQUITE + BACKSLASH + DOUBLEQUOTE;

In a verbatim string (a string starting with #"") to escape double quotes you use double quotes, e.g. #"Please press ""Ok"".". If you want to do it with verbatim strings then you would do something like #"\""" (that's 3 double quotes on the end there).

You can do like this,
string s = "something'\\\'";
Use a single '' rather then "" in string to do the same.

Why doesn't my code compile?

I am using regular expression in code behind file and defining string as
string ValEmail = "\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*";
if (Regex.IsMatch(email, "\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*"))
{ }
else
{ }
It gives me warning and does not compile. How can I define such string combination?.

In C# the backslash is a special character, if it is to represent a backslash we need to inform the compiler as such.
This can be achieved by escaping it with a backslash:
string ValEmail = "\\w+([-+.']\\w+)*#\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*";
Or using an # prefix when constructing the string:
string ValEmail = #"\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*";

The backslash is the escape char in c# strings. Technically you have to escape the backslash with another blackslash ("\\") or just add an # before your string:
string ValEmail = #"\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*";

Use #"\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*" so the backslashes will get escaped

How can i declare ^\ in a string or character

I would like to declare ^\ this as a string or character. I used the below but i am getting an error
string str="^\";
So can any one help me

You have to escape the backslash.
string str = "^\\";
Or, you can use the verbatim syntax.
string str = #"^\";

\ is the escape token, you have to double it to use it as a literal in a string:
string str = "^\\";
Alternatively, you can use literal string syntax:
string str = #"^\";

You need to escape backslash characters, so instead of:
string str = "^\";
use:
string str = "^\\";

I have no idea about C#, but can you try:
string str="^\\";

string replace single quote to double quote in C#

How can I replace a single quote (') with a double quote (") in a string in C#?

You need to use the correct escape sequence for the quotes symbol, you can find more information about escape sequencies here.
String stringWithSingleQuotes= "src='http://...';";
String withDoubleQuotes = stringWithSingleQuotes.Replace("'","\"");

var abc = "hello the're";
abc = abc.Replace("'","\"");

string str;
str=strtext.Replace('"','\'');