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

You can escape a backslash using a backslash.

//String
string backslash = "\\";

//Character
char backslash = '\\';

You can use the string literal.

string backslash = @"\";
char backslash = @"\"[0];

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.

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