“字符文字错误中字符过多”

You cannot treat == or || as chars, since they are not chars, but a sequence of chars.

You could make your switch...case work on strings instead.

A char can hold a single character only, a character literal is a single character in single quote, i.e. '&' - if you have more characters than one you want to use a string, for that you have to use double quotes:

case "&&":

This is because, in C#, single quotes ('') denote (or encapsulate) a single character, whereas double quotes ("") are used for a string of characters. For example:

var myChar = '=';


var myString = "==";

Here's an example:

char myChar = '|';
string myString = "||";

Chars are delimited by single quotes, and strings by double quotes.

The good news is C# switch statements work with strings!

switch (mytoken)
{
case "==":
//Something here.
break;
default:
//Handle when no token is found.
break;
}

I believe you can do this using a Unicode encoding, but I doubt this is what you really want.

The == is the unicode value 2A76 so I belive you can do this:

char c = '\u2A76';

I can't test this at the moment but I'd be interested to know if that works for you.

You will need to dig around for the others. Here is a unicode table if you want to look:

http://www.tamasoft.co.jp/en/general-info/unicode.html

I faced the same issue. String.Replace('\\.','') is not valid statement and throws the same error. Thanks to C# we can use double quotes instead of single quotes and following works String.Replace("\\.","")