How to Write the Escape Char '\' to Code

How do I write the escape char '\' to code

You just need to escape it:

char c = '\\';

Or you could use the Unicode escape sequence:

char c = '\u005c';

See my article on strings for all the various escape sequences available in string/character literals.

How to write escape character to string?

In a normal string, you use \\

If this is in a regular expression, it needs to be \\\\

The reason RegEx needs four is because both the String parser and RegEx engine support escapes. Therefore, \\\\ is parsed to \\ by the String parser then to a literal \ by the RegEx parser.

How do i print escape characters as characters?

Escape the slashes (use " \\a") so they won't get interpreted specially. Also you might want to use a lookup table or a switch at least.

switch (c) {
case '\0':
    printf("   \\0");
    break;
case '\a':
    printf("   \\a");
    break;
/* And so on. */
}

How to escape special characters in building a JSON string?

A JSON string must be double-quoted, according to the specs, so you don't need to escape '.

If you have to use special character in your JSON string, you can escape it using \ character.

See this list of special character used in JSON :

\b  Backspace (ascii code 08)
\f  Form feed (ascii code 0C)
\n  New line
\r  Carriage return
\t  Tab
\"  Double quote
\\  Backslash character

However, even if it is totally contrary to the spec, the author could use \'.

This is bad because :

It IS contrary to the specs
It is no-longer JSON valid string

But it works, as you want it or not.

For new readers, always use a double quotes for your json strings.

How do I escape characters in GitHub code search?

I dont think you can escape characters for github

From searching code doc:

You can't use the following wildcard characters as part of your search
query: . , : ; / \ ` ' " = * ! ? # $ & + ^ | ~ < > ( ) { } [ ]. The
search will simply ignore these symbols.

How can I add escape characters to a Java String?

I'm not claiming elegance here, but i think it does what you want it to do (please correct me if I'm mistaken):

public static void main(String[] args)
{
    String example = "Hello, I'm\" here";
    example = example.replaceAll("'", "\\\\'");
    example = example.replaceAll("\"", "\\\\\"");
    System.out.println(example);
}

outputs

Hello, I\'m\" here

Can I convert a C# string value to an escaped string literal?

There's a method for this in Roslyn's Microsoft.CodeAnalysis.CSharp package on NuGet:

private static string ToLiteral(string valueTextForCompiler)
{
    return Microsoft.CodeAnalysis.CSharp.SymbolDisplay.FormatLiteral(valueTextForCompiler, false);
}

Obviously, this didn't exist at the time of the original question, but it might help people who end up here from Google Search.

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.

Rules for C++ string literals escape character

Control characters:

(Hex codes assume an ASCII-compatible character encoding.)

\a = \x07 = alert (bell)
\b = \x08 = backspace
\t = \x09 = horizonal tab
\n = \x0A = newline (or line feed)
\v = \x0B = vertical tab
\f = \x0C = form feed
\r = \x0D = carriage return
\e = \x1B = escape (non-standard GCC extension)

Punctuation characters:

\" = quotation mark (backslash not required for '"')
\' = apostrophe (backslash not required for "'")
\? = question mark (used to avoid trigraphs)
\\ = backslash

Numeric character references:

\ + up to 3 octal digits
\x + any number of hex digits
\u + 4 hex digits (Unicode BMP, new in C++11)
\U + 8 hex digits (Unicode astral planes, new in C++11)

\0 = \00 = \000 = octal ecape for null character

If you do want an actual digit character after a \0, then yes, I recommend string concatenation. Note that the whitespace between the parts of the literal is optional, so you can write "\0""0".